Objective and subjective evaluation of the use of protective clothing on the thermal strain and mental workload of nurses during the Covid-19 pandemic

Abstract

BACKGROUND:

Nurses are among high-risk occupational groups during the outbreak of epidemics. Therefore, these people are required to use personal protective equipment (PPE). Previous studies have shown that the use of personal protective equipment can affect people’s thermal strain and mental workload.

OBJECTIVE:

The present study was conducted with the aim of objectively and subjectively evaluating the use of protective clothing on the thermal strain and mental workload of nurses during the covid-19 pandemic.

METHODS:

This cross-sectional study was divided into two groups with a sample size of 300 people who were selected by systematic random method. In the first group, 120 people were objectively evaluated (use of protective clothing). In the second group, 180 people only completed the questionnaire of mental workload, feeling of heat and sweating and other information related to the type of clothing and the duration of its use, etc. Measurements were done in August and September of 2021 and in the morning shift of hospitals. Data were analyzed using SPSS version 21 software and chi-square, independent T-test and linear regression tests.

RESULTS:

The average age and average working hours per month of the participants in the study were 33.51±7.88 years, 187.91±35.37 hours, respectively. The results showed that the predicted average vote (PMV) index and the predicted percentage of dissatisfied (PPD), moisture felt on the skin surface, the feeling of desirability and pleasantness of the temperature, the weight of sweat and the humidity inside the clothes between the two groups of people using insulated clothes There is a significant difference between medicine and dressing (P < 0.05). There was a significant relationship between mental workload and type of clothing, average working hours per month.

CONCLUSIONS:

The use of medical isolation clothes causes a high heat load on nurses and can increase their mental workload. On the other hand, people using normal gowns suffer from a high mental workload due to the fear of disease due to the uncertainty of high-level protection. In addition, medical isolation clothes increase the humidity of the skin due to their impermeability, which causes skin complications.

Keywords

Nurses medical isolation clothes mental workload heat strain heat stress physiological strain

1 Introduction and background

Based on the studies conducted, the Covid-19 disease, as an epidemic, has caused a severe shock to the healthcare system of most countries in the world, and one of the main problems in dealing effectively with this disease is the lack of specialists and doctors and care workers, especially nurses. Which has led to the extension of mandatory working hours and the cancellation of many personal and recreational programs of nurses [1]. In fact, nurses play a role as the front line of fighting this disease in cases such as diagnosis, treatment and care of sick patients. Therefore, high work pressure and exposure to the risks of contracting this disease have brought a double mental burden for yourself and your family [24]. In addition, the occurrence of special conditions such as epidemics and epidemics of patients (such as Sars, cholera, influenza, etc.) can strengthen psychologically harmful factors and cause more psychological harm to people. The mentality of health service providers is different from normalconditions [2].

According to the report of the World Health Organization, until the end of December 2019, corresponding to January 19, 2021, about 96 million people have contracted this disease and about 2,049,769 people have lost their lives [42]. In Iran, according to the reports of the Ministry of Health, since February 30, 2018, the first cases of this disease appeared in the country, and until the end of December 2019, the total number of infected people was 1,336,217, of which 1,125,499 people recovered and 56,886 people have lost their lives [43, 44].

One of the main concerns and tensions of nurses in caring for patients with contagious infectious diseases such as Covid-19 is how to care for the patient against the disease and prevent it. Since the disease covid-19 is diagnosed among other diseases, it can have severe symptoms and complications and can even take a person’s life, paying attention to the issues that exist there and how to He was caught by it. Disease is of significant importance [3]. In this regard, adherence to strict guidelines and protocols to maintain the safety of health care personnel and especially nurses in treating patients with diseases has been recommended by the World Health Organization and other international healthorganizations [4].

Studies have shown that the problems of protecting nurses against corona disease include: dehydration, sores on the nose and face, feeling of shortness of breath, lack of priority given by hospital managers in the distribution of protective equipment and delay in providing personal protective equipment on time, actually due to the fear of contamination. As well as high work pressure, many nurses did not have the opportunity to drink enough fluids while working and using these care equipment’s, and this may expose nurses’ health to serious risks [5]. In general, the use of full PPE 1 in the treatment staff has caused many problems for them. Personal protective equipment used by health care workers to reduce the risks of disease transmission while caring for patients with dangerous infectious diseases can disrupt the body’s natural cooling mechanisms and exacerbate physiologicalstress [6].

The long-term use of these equipment’s and the creation of a humid environment have brought a lot of thermal load to the treatment staff, especially in the summer season and when there is a lot of work and activity. Studies have shown that exposure to occupational heat stress can affect a person’s performance and concentration and cause human error due to lack of concentration and heatstroke. Studies have shown that heat stress can reduce concentration and performance and increase the occurrence of errors [7] and the more people are exposed to heat stress, the more errors they make [8]. In environments with high heat stress, the effect of ambient heat and metabolic heat created as a result of a person’s activity are combined and cause heat storage in the body [9]. Subsequently, the deep body temperature increases and can cause physiological effects such as sweating, increased body temperature and increased heart rate, resulting in heat stress. Heat stress occurs when exposed to hot climatic conditions, doing heavy physical work and wearing clothes and personal protective equipment insulated against heat or impermeable against water vapor. The consequences of occupational exposure to heat are initially in the form of heat stress or heat stress (the body’s physiological response to heat). Long-term exposure to heat and persistence of heat stress leads to disorders such as heat exhaustion, heat syncope, muscle cramps, and heatstroke, reducing physical and mental performance, reducing productivity, and increasing the incidence of accidents [10, 11].

Considering the effects of excessive heat on people’s health, it is important to evaluate the heat stress caused by protective clothing in the medical staff. During the outbreak of different diseases, health care workers use different personal protective equipment according to the type of disease, and according to the type of equipment used, they are affected by various physical and physiological stresses [12]. Currently, due to the spread of the Covid-19 disease, the use of full protective clothing along with masks and shields is unavoidable due to thermal stress caused by these devices, so it is important to pay attention to this factor [23]. On the other hand, the increase in the burden of referrals to hospitals and health centers and the increase in the amount of work hours and workload, the reduction of rest times has caused an increase in the mental workload of health and treatment personnel, especially doctors and nurses, and it is important to pay attention to this [13].

Various studies have shown that Workload is considered as one of the major problems of job demand and is considered as a dangerous factor in the development of cardiovascular diseases. Studies show that high workload causes fatigue, performance loss, memory loss, processing defects, irritability and learning loss. On the other hand, low workload can also lead to depression and reduce the person’s understanding of the situation [14, 15]. Also, tired people are more likely to choose risky behaviors such as using shortcuts to complete their tasks [16]. Also, heavy workload reduces job satisfaction, motivation and burnout. Due to the fact that mental workload has a direct relationship with a person’s performance and is one of the factors affecting people’s health, safety and comfort [17]. Assessing the mental workload of health care workers who deal with human lives is very important, because the high workload not only affects their health, but also affects their performance in performing their duties [18].

Considering the high importance of maintaining the health of treatment personnel and preventing medical errors and accidents, examining the effects of personal protective equipment used during a disease epidemic such as Covid-19 can be an important step in this direction. Therefore, the aim of this study was to objectively and subjectively evaluate the use of protective clothing on thermal stress and mental workload in nurses during the Covid-19 pandemic.

2 Methods

2.1 Determining the sample size

This study was cross-sectional and using Statistics and sample size software and the following formula, with a confidence level of 0.05, prevalence of 0.5 and error of 0.06, the sample size of 267 people was estimated. In order to avoid sample loss, the final sample size was determined to be 300 people. $n \geq \frac{Z_{1 - α / 2}^{2} \times p (1 - p)}{d^{2}}$

The study subjects were selected by a systematic random method from among the nurses working in the Covid-19 ward who used isolated protective clothing and the nurses working in other departments of public hospitals who used gowns.

In order to conduct objective evaluations between two groups with different coverings based on skin temperature and using the following formula, 120 people were selected, out of which 60 people were wearing medical isolation clothes who were active in the care of corona patients and there were 60 people who used gowns who were working in other hospital departments. $n = \frac{2 σ^{2} (Z_{β} + Z_{α / 2})^{2}}{{difference}^{2}}$

300 people were selected for mental evaluations based on mental workload and using the following formula, 120 questionnaires were completed in person and 180 questionnaires were completed electronically. Questionnaires on mental workload, feeling of heat and sweating, information on the type of clothing and the duration of its use, the effects of heat caused by the use of lip balms and facial expressions to determine the parts of the body that have skin complications due to the use of personal protective equipment was also completed by nurses.

The subjects of the study for the sampling method are among the nurses working in the corona department who used isolated protective clothing and the nurses working in other hospital departments, public hospitals. According to the conditions of the corona disease epidemic at the time of the beginning of the study, in order to select samples that use medical isolation clothes, hospitals that have an active care department for covid-19 patients and have a significant number of hospitalized people were selected to enter the study and to select samples with hospital gowns randomly selected. In order to select the people participating in the study, referring to the hospitals, in the first step, the plan was introduced to the supervisors, and then the supervisors introduced the plan to the nurses under their coverage, and the nurses who agreed to participate in the study based on the eligibility criteria Being in order to participate in the study to enter the sample. It should be noted that the type of clothing, the type of mask, the covering of people under the clothing, eye protection and head covering were the same in the selected individuals. The measurement was done in August and September 2021 in the morning shift of the hospital.

According to the conditions of the epidemic of covid-19 disease at the time of the beginning of the study, in order to select a sample with Medical Isolation Gown (Fig. 1- right side), hospitals that had an active care department for covid-19 patients and had a significant number of hospitalized patients were selected to enter were selected for the study. And to select samples with Medical Gown (Fig. 1 – left side), hospitals were randomly selected. In order to select the participants in the study, they were introduced to the supervisors by referring to the hospitals in the first step of the design and study, and then the desired number of people were selected based on the conditions of entering and exiting the study. It should be noted that the type of mask, covering people under the clothes, eye protection and head covering are the same for the selected people. The measurements were carried out in August and September of the summer of 2022 and in the morning shift of hospitals.

Fig. 1

Medical isolation gown (Right) – Medical Gown (Left).

2.2 Inclusion and exclusion criteria

Willingness to participate in the study

Possessing complete physical and mental health

Not having cardiovascular diseases

Not having neuromuscular diseases

Not having musculoskeletal diseases

Not having diabetes

Not having lung diseases

Not using blood pressure regulating drugs

Not using drugs that regulate heart rate

In the designed questionnaire (paper and electronic), a question was asked about the history of cardiovascular, neuromuscular, musculoskeletal, diabetes, lung diseases, etc., and the use of blood pressure and heart rate regulating drugs. The positive answer of the participant, that questionnaire was not included in the examined sample.

3 Tools

3.1 Subjective Evaluation Tools

3.1.1 Questionnaire of demographic characteristics

This questionnaire included questions about age, gender, history of cardiovascular, neurological, skeletal-muscular diseases, average working hours per month and dedicated resting place.

3.1.2 Questionnaire of heat symptoms caused by working conditions and environment

Here, people were asked whether they had experienced symptoms including headache, dizziness, vomiting, excessive sweating, heavy breathing, dehydration, and fatigue in the workplace under the conditions of the workplace during the past week. The heat symptoms raised in this questionnaire were extracted based on the study of Lee et al [38].

3.1.3 Questionnaire for assessing skin complications caused by the use of personal protective equipment

Here, using a body map, people were asked if they had experienced skin complications such as eczema, acne, burning sweat, etc. during the past week due to the use of personal protective equipment, and if the answer was positive, Mark the problem areas on the picture.

3.1.4 Thermal comfort questionnaire

A questionnaire introduced by ISO standard 10551 was used to determine the indices PMV 2 and PPD 3 [39].

3.1.5 NASA-TLX 4 mental load questionnaire

The NASA Workload Index was developed by the NASA Research Center’s Human Performance Group. This index is a multidimensional rating method containing 6 subscales, mental demands, physical demands, time demands, performance, effort level and frustration level. The first three subscales are related to the participant’s needs and the last three are related to the participant’s interaction with the task. Numerical rating for each subscale is specified by the participant on a line divided into 20 equal intervals, each axis is evaluated by the individual with a scale of 0-100 with 5-point steps. The raw loading score is calculated by summing the ratings provided for all six subscales and dividing it by six. The validity of the Persian version of this scale has been confirmed by Mohammadi and his colleagues, and its internal correlation (α= 0.847) [19] has been evaluated as appropriate.

3.2 Objective Evaluation Tools

3.2.1 Temperature and humidity USB data logger

The temperature and humidity USB data logger model 98583 is made by MIC company in Taiwan and according to the program given to the device, the temperature and humidity are recorded every ten minutes and at the end of the measurement the recorded data is extracted as an Excel file using the data logger software [40]. becomes In this study, considering that the measurement duration is 120 minutes, humidity and temperature have been recorded for each person at 12 time points.

This device was also used to measure the temperature and humidity of the environment. The temperature and humidity of the environment were measured and recorded at the beginning of the shift, the middle of the shift, and the end of the shift.

Fig. 2

Temperature and humidity data logger.

3.2.2 Skin temperature measuring device

Non-contact infrared forehead thermometer 01PA with LCD screen uses infrared technology to measure temperature without contact and in a hygienic way.

The thermometer with high accuracy and digital screen can display the measurement result in 2 types of degrees Celsius and degrees Fahrenheit. It can set sound alarms when the temperature is too high, show the body temperature status with 3 color change display. The screen colors include: green color when the temperature is normal, yellow color shows high temperature. And red color indicates very high temperature. The device will automatically turn off within 7 seconds if not in use. Small size, light weight, easy to carry are other advantages of this device.

How to use: Hold the device at a distance of 5–15 cm from the measuring point and press the trigger to measure the temperature.

Temperature range: 34–42.9 degrees Celsius

Age group: toddler, adult.

To measure the average temperature of the skin, the 4-point pattern recommended by ISO 9886 (back of the head, right chest, left wrist and front right leg) was used. For measuring, laser thermometer FS-300, non-contact infrared thermometer “Thermofinder”, made by HuBDIC Company from Republic of Korea was used. After the measurement, the average skin temperature was calculated using the following relationship [41].

Tsk =∑ki × tski

Tsk: average skin temperature

Ki: surface coefficients of selected skin points

TsKi: skin surface temperature at selected points

The value of Ki for the back of the head, chest and leg is equal to 0.28 and for the left wrist is equal to 0.16.

Fig. 3

Skin temperature measuring device.

3.2.3 Core temperature measuring device

Core body temperature was measured based on the temperature of the tympanic membrane and using an infrared tympanic thermometer model Ri-thermo N made by Riester company in Germany.

In order to determine the core body temperature in this study, the eardrum temperature was measured. In order to measure, first, using an otoscope, the absence of cerumen in the ear canal was ensured, then, following the principles of measuring the temperature of the eardrum, it was measured and recorded in two time periods (before installing the temperature and humidity data logger and 2 hours later).

Fig. 4

core temperature measuring device.

3.2.4 Blood oxygen and heart rate measuring device

In this study, a fingertip pulse oximeter was used to measure heart rate and blood oxygen levels at the beginning and end of the two-hour period. The purpose of measuring heart rate and core body temperature is to calculate the physiological strain index and compare these two parameters in people with different types of clothing. To measure heart rate and blood oxygen, fingertip pulse oximeter model lk-88 made in China was used.

Physiological Strain Index (PSI) is one of the thermal and physiological strain evaluation indices that scales thermal strain in the range of 0–10. The number zero indicates the lack of stearin and the number ten indicates the maximum stearin. This index takes into account the load on the cardiovascular system and the thermal regulation of the body, which is calculated according to the following formula [20]. $PSI = \frac{5 (T_{ct} - T_{c 0})}{(39.5 - T_{c 0})} + \frac{5 ({HR}_{ct} - {HR}_{c 0})}{(180 - {HR}_{c 0})}$

Tct: core body temperature at every moment of measurement

Tc0: core body temperature at rest before starting the activity protocol

HRct: heart rate at each moment of measurement

HRc0: resting heart rate before starting the activity protocol

Fig. 5

Device for measuring blood oxygen and heart rate.

3.2.5 Body weight measuring device

In this study, a PS240 digital scale model of Armin Derman Medical Equipment Company, the exclusive representative of German beurer products in Iran, was used to determine the amount of sweating done by the weight of people at the beginning and end of the two-hour period.

Fig. 6

Body weight measuring device.

4 Procedure

4.1 Collect objective data

After considering the inclusion and exclusion criteria, a total of 120 people were included in the study for objective measurements, of which 60 people had coveralls (medical isolation) and 60 people had gowns.

Collecting objective data was done in five steps.

First step: The questionnaires were completed by the participants.

Second step: environmental parameters including temperature and humidity were measured in specific time intervals and in the places where nurses had the most traffic.

Third step: individual parameters including: skin temperature, depth temperature, blood oxygen level, heart rate, weight of people were measured inside the clothes before connecting the data logger.

Fourth step: The temperature and humidity data logger USB device was installed inside the people’s clothes in such a way that the sensor of the device was not in direct contact with the body’s skin and the location of the device was in the middle of the chest, for two reasons: first, it does not interfere with the person’s work, and second. With the measurements that were done before the start of the study, it was determined that this point is the hottest point compared to other parts of the body. After installing the device, the person returned to his work station and performed his duties for 2 hours.

Fifth step: After 2 hours, the device was removed and again the skin temperature at four points, depth temperature, heart rate, blood oxygen level and the person’s weight were measured and recorded. And the information recorded by USB data logger was extracted with data logger software in Excel file format.

In order to use the data collected by the temperature and humidity data logger, averaging was done from the collected data of each parameter for each person.

The start time of the measurements was the first half hour of the start of the morning shift, and the devices were connected to the participants for two hours, and the measurement ended after two hours. And this 2-hour period was measured once for each person.

The people participating in the study did not change their clothes from the beginning to the end of the night, the only protective equipment was protective gloves, which was done in case of tears or the need to examine the patients.

The used pulse oximeter had the ability to display the heart rate and blood oxygen level in real time and could display the heart rate at the beginning and end of the desired time period.

Core temperature, heart rate, blood oxygen, weight of people, skin temperature were measured only at the beginning and end of the desired time period and were recorded on paper, and the only parameters that were measured and recorded during the desired time period were temperature and The humidity inside the clothes was recorded by the USB data logger device and stored in the device’s memory. After the measurement was finished, it was extracted as an Excel file using the laptop and the program related to the device itself.

It should be noted that the weight of water or food eaten and urine excreted were measured and recorded in a two-hour period.

4.2 Subjective data collection

Part of the questionnaire data was collected electronically due to the peak of the Covid-19 disease and the high work pressure of nurses. Questionnaires were designed in the press line and by referring to the nursing office of the hospitals, the questionnaire link was provided to the supervisors and they provided the link to the nurses under their coverage and 180 questionnaires were completed.

4.3 The method of information extraction and statistical inference

The data was analyzed using SPSS version 21 software. Chi-square test was performed to compare heat symptoms and parts of the body that have skin complications due to the use of personal protective equipment between two groups with different coverage. In order to compare other collected data, an independent T-test was performed. By performing a linear regression test, the relationship between the physiological strain index and clothes, age, gender, average working hours per month and rest room was investigated.

5 Results

5.1 Findings from subjective evaluation

The demographic characteristics of the people who completed the questionnaires are shown in Table 1.

Table 1
Distribution of the frequency of demographic characteristics of people who completed the questionnaire (n = 300)

Variable Frequency (n) Percentage (%)

Gender Male 85 28.33

Female 215 71.66

Type of clothes Medical isolation gown Male 36 12.00

Female 101 33.66

Medical gowns Male 49 16.33

Female 111 37.00

Rest place has it 171 57.00

has no 129 43.00

Activity section Care of patients with covid-19 126 42.00

Caring for other patients 174 58.00

Variable			Frequency (n)	Percentage (%)
Gender	Male		85	28.33
	Female		215	71.66
Type of clothes	Medical isolation gown	Male	36	12.00
		Female	101	33.66
	Medical gowns	Male	49	16.33
		Female	111	37.00
Rest place	has it		171	57.00
	has no		129	43.00
Activity section	Care of patients with covid-19		126	42.00
	Caring for other patients		174	58.00

5.1.1 Findings from experienced heat symptoms

The symptoms of heat reported by people due to working conditions and environment are shown in Table 2. The most reported symptom in people wearing integrated isolation clothing and medical gown is fatigue, which respectively 72.14 and 68.75 percent of people in each group reported this symptom. The second symptom reported in people wearing integrated isolation clothing’s thirst, which was reported by 60% of people. Headache is the second most common symptom reported by 58.12% of people wearing a headscarf. The third reported symptom was headache with 49.28% in people wearing coveralls and thirst with 47.50% in people wearing coveralls. Therefore, the three symptoms with the highest priority that were reported by each group are as follows.

Table 2
Distribution of the Percentage of heat symptoms caused by the conditions and work environment (n = 300)

Coverage Thermal symptoms

Headache Dizziness Thirst Vomit Profuse sweating Breathing hard Dehydration Fatigue

Medical isolation gown 49.28 27.14 60.00 4.28 46.42 46.42 48.57 72.14

Medical Gowns 58.12 23.75 47.50 3.12 35.00 31.25 38.12 68.75

P-value^* 0.125 0.50 0.03 0.59 0.04 0.007 0.06 0.52

Coverage	Thermal symptoms
Medical isolation gown	49.28	27.14	60.00	4.28	46.42	46.42	48.57	72.14
Medical Gowns	58.12	23.75	47.50	3.12	35.00	31.25	38.12	68.75
P-value^*	0.125	0.50	0.03	0.59	0.04	0.007	0.06	0.52

Also, by performing the Chi-square test, it was found that there is a significant difference between the two groups in the occurrence of symptoms of thirst, excessive sweating, and difficult breathing (P < 0.05).

5.1.2 Findings from determining the parts of the body that have skin complications

The parts of the body of people who have skin complications due to the use of personal protective equipment are listed in Table 3. The three places where most people have skin complications in that area are as follows:

Table 3
Comparison of the Percentage of the parts of the body that have skin complications caused by personal protective equipment in nurses with two different types of clothing (n = 300)

Coverage Parts of the body that have skin complications

Face Head Neck Hands Legs Waist Chest Abdomen

Medical isolation gown 52.85 13.75 22.14 45.00 29.28 12.85 15.71 3.75

Medical Gowns 38.75 11.87 16.25 39.37 24.37 7.50 8.75 1.87

P-value^* 0.01 0.65 0.19 0.32 0.33 0.12 0.06 0.36

Coverage	Parts of the body that have skin complications
Medical isolation gown	52.85	13.75	22.14	45.00	29.28	12.85	15.71	3.75
Medical Gowns	38.75	11.87	16.25	39.37	24.37	7.50	8.75	1.87
P-value^*	0.01	0.65	0.19	0.32	0.33	0.12	0.06	0.36

People with integrated isolation clothing: face (52.85%), hands (45.00%), legs (29.28%).

People with medical gowns: hands (39.37%), face (38.75%), legs (24.37%)

Also, by performing the Chi-square test, it was found that there is a significant difference between the two groups in causing skin complications on the face (P = 0.01).

5.1.3 Findings from the determination of the average predicted vote index and subjective dissatisfaction percentage and its relationship with the type of clothing used

The mean score of PMV in two groups of nurses with different coverage is shown in Table 4. By performing the independent t-test, a significant difference was observed between the two groups (P = 0.002).

Table 4
Average predicted score of nurses with two different types of coverage (n = 300)

Variable Mean ± SD Min Max P-value^*

Predicted Mean Vote (PMV) Medical isolation gown 1.99 ± 0.086 0 3 0.002

Medical Gowns 1.62 ± 0.081 0 3

Variable		Mean ± SD	Min	Max	P-value^*
Predicted Mean Vote (PMV)	Medical isolation gown	1.99 ± 0.086	0	3	0.002
	Medical Gowns	1.62 ± 0.081	0	3

Using the chart to determine the PPD based on the PMV, the percentage of mental dissatisfaction in people with integrated isolation clothes is 75% and in people with medical gowns is 50%.

The PPD is shown in Table 5. By performing the independent t-test, a significant difference was observed between the two groups (P = 0.02).

Table 5

Comparing the percentage of nurses’ dissatisfaction with two different types of coverage (n = 300)

Variable		Very displeased	Dissatisfied	A little dissatisfied	Neutral	A little satisfied	Satisfied	P-value^*
PPD	Medical isolation gown	27.14	28.57	16.42	11.42	10.00	6.42	0.023
	Medical Gowns	15.00	26.87	25.00	11.28	11.25	10.63

5.1.4 Findings from measuring mental workload and its relationship with the type of clothes used

The average mental workload measured is shown in Table 6. According to the independent t-test results, a significant difference in mental workload was observed between the two groups (P = 0.00).

Table 6
The results of evaluating the effect of using two different types of coverings on Heat sensation, Moist feeling of the skin and A pleasant temperature sensation (n = 300)

Variable Mean ± SD P-value^*

Heat sensation Medical isolation gown 5.68±0.097 0.32

Medical Gowns 5.56±0.076

Moist feeling of the skin Medical isolation gown 0.31±0.113 0.01

Medical Gowns –0.11±0.113

A pleasant temperature sensation Medical isolation gown –1.75±0.88 0.03

Medical Gowns –1.49±0.082

Variable		Mean ± SD	P-value^*
Heat sensation	Medical isolation gown	5.68±0.097	0.32
	Medical Gowns	5.56±0.076
Moist feeling of the skin	Medical isolation gown	0.31±0.113	0.01
	Medical Gowns	–0.11±0.113
A pleasant temperature sensation	Medical isolation gown	–1.75±0.88	0.03
	Medical Gowns	–1.49±0.082

By performing a linear regression test, the relationship between mental workload and clothing, age, sex, average working hours per month and rest room was also investigated. That there was a significant relationship between mental workload and type of clothing, average working hours per month (P < 0.05).

5.2 Findings from objective evaluation

5.2.1 Findings from objectively determining the PMV and PPD and its relationship with the type of clothing used

According to the findings, the value of PMV in the lowest and highest measured temperature of the environment is in the hot zone, and at the lowest temperature, 31.11% of people were dissatisfied, and at the highest temperature, 52.42% of people were dissatisfied. Considering that measuring PMV and PPD objectively can only be done for people with permeable clothing, the findings are related to people with normal clothing (medical gown).

5.2.2 Findings from depth temperature measurement and its relationship with the type of clothing used

According to the independent t-test, there was no significant difference between the depth temperature measured at the beginning and the end of the time period between the two groups (P < 0.05).

By performing a linear regression test, the relationship between the measured depth temperature with clothing, age, sex, average working hours per month and rest room was investigated. A significant difference was observed between the depth temperature of clothing and the rest room (P < 0.05).

5.2.3 Findings from blood oxygen measurement and its relationship with the type of clothes worn

According to the independent t-test, there was no significant difference in the blood oxygen level between the two groups at the beginning and end of the time period (P < 0.05). By performing a linear regression test, the relationship between blood oxygen level and clothes, age, gender, average working hours per month and rest room was investigated. No significant difference was observedbetween them.

5.2.4 Findings from heart rate measurement and its relationship with the type of clothes worn

According to the independent t-test, no significant difference was observed in the heart rate measured at the beginning and end of the desired time period between the two different groups. By performing a linear regression test, the relationship between heart rate and clothing, age, sex, average working hours per month and rest room was investigated. No significant difference was observed between them.

5.2.5 Findings from the average skin temperature and its relationship with the type of clothes worn

The average skin temperature measured at the beginning and end of the measurement is shown in Table 7. According to the independent t-test, there was no significant difference in the average skin temperature at the beginning between the two groups (P < 0.05). But in the average skin temperature measured at the end, a significant difference was observed between the two groups. (P = 0.00).

Table 7
Comparison of the average mental workload measured in nurses with two different types of coverage (n = 300)

Variable Mean ± SD Min Max P-value^*

Mental workload Medical isolation gown 71.07 ± 13.35 31.66 100 0.009

Medical Gowns 74.69 ± 14.36 20 100

Variable		Mean ± SD	Min	Max	P-value^*
Mental workload	Medical isolation gown	71.07 ± 13.35	31.66	100	0.009
	Medical Gowns	74.69 ± 14.36	20	100

By performing a linear regression test, the relationship between skin temperature and clothing, age, gender, average working hours per month and rest room was investigated. No significant difference was observed between them.

5.2.6 Findings from the measurement of physiological strain and its relationship with the type of clothing used

The average measured physiological strain is shown in Table 8. According to the independent t-test, no significant difference was observed between the two groups.

Table 8
The average physiological strain index measured in nurses with two different types of clothing (n = 120)

Variable Mean ± SD P-value^*

Physiological strain index Medical isolation gown 1.33 ± 0.86 0.066

Medical Gowns 1.04 ± 0.83

Variable		Mean ± SD	P-value^*
Physiological strain index	Medical isolation gown	1.33 ± 0.86	0.066
	Medical Gowns	1.04 ± 0.83

By performing a linear regression test (Table 9), the relationship between physiological strain index and clothes, age, gender, average working hours per month and rest room was investigated. There was a significant relationship between physiological strain index and clothes and rest room. (P < 0.05)

Table 9

The results of evaluating the effect of clothing, age, gender, Average hours of work per month and rest room on the physiological strain index (n = 120)

	Variable	B	Confidence interval (% 95)	P-value^*
PSI	Clothing	2.12	(0.48) – (3.77)	0.01
	Age	0.002	(–0.018) – (0.022)	0.82
	Gender	0.039	(–0.30) – (0.38)	0.82
	Average hours of work per month	–0.0009	(–0.004) – (0.003)	0.63
	Rest place	–0.41	(–0.73) – (0.08)	0.01

5.2.7 Findings from measuring the humidity inside people’s clothes

According to the independent t-test, there was a significant difference between the two groups in the humidity measured inside the clothes at different minutes. The average working hours per month and the rest room were examined. No significant difference was observed between them.

6 Discussion

Risk factors increase the use of specific objective equipment such as N95 and FFP2 masks and medical isolation clothes, shields among the medical staff. Equipment that fully protects against disease. The prolongation of the duration of the pandemic and as a result the long-term use of these special equipment’s for the treatment staff.

In the studies conducted regarding medical protective clothing, three cases were observed. The first of these studies was conducted with very small sample sizes. The second case is conducting studies in laboratory environments and under defined and controlled conditions, both of which are considered in this study, and the third case is that the studies conducted were not on gowns and were conducted specifically on isolated clothes. Will be has been done and no comparison has been made between isolated clothes and coveralls.

6.1 Experienced heat symptoms

The study conducted by Joseh et al. showed that the most common adverse health effects expressed by nurses on the front line of the fight against Corona, who used personal protective equipment, were headache, excessive sweating, and difficulty breathing, respectively [21]. Kaglar’s study also showed that the most common symptoms associated with personal protective equipment include headache, difficulty breathing, heart palpitations, and skin dermatitis [22]. Various other studies have also shown that fatigue, thirst and skin problems are common side effects of using personal protective equipment during the Covid-19 pandemic among healthcare workers on the front line of fighting the disease. These results are consistent with the findings of the present study, which show that the main side effects reported by nurses using personal protective equipment, including medical isolation gowns, include: fatigue, thirst, and headache. According to the conversations held with the nurses during the work, it was found that the intensity of these symptoms are more visible in the middle hours of the day, that is, between 11 : 00 and 15 : 00 and also when the number of visitors is more.

6.2 Skin complications caused by the use of personal equipment

The use of personal protective equipment by nurses is effective in causing skin complications. During the outbreak of the Covid-19 disease, long-term use of this equipment has caused various skin complications. Doan et al.’s study showed that frontline personnel were uncomfortable with allergic dermatitis, trunk and limb skin rashes, and fungal skin diseases [23]. Also, the study of Lee et al showed that the use of personal protective equipment causes inflammation and skin infections due to the accumulation of moisture on the skin and the closing of the epidermal barrier [24].

The present study also showed that nurses wearing protective clothing (medical isolation) have the most skin complications (pimples, acne, eczema, burning sweat, etc.) in the areas of the face, hands, and feet, respectively, and in nurses using normal clothing (The most skin complications are in the areas of the hands, face and feet, respectively.

The appearance of boils, acne, eczema, etc. in different parts of people’s bodies causes discomfort in nurses, so that some of them expressed their discomfort with the permanence of these side effects. In addition to the complications caused by the use of personal protective equipment, excessive use of detergents and disinfectants causes skin complications in the hands and face. During the study and discussion with nurses, this issue was raised a lot.

6.3 Average predicted vote and percentage of dissatisfaction

Lembo’s study also showed that the use of additional personal protective equipment significantly increases the insulation level of clothing and eases the conditions of thermal discomfort in workers [25]. Another study conducted by Ghiashi showed that the weight caused by personal protective equipment indirectly increases the energy consumption and temperature and creates significant changes in the index of the average predicted vote and the percentage of dissatisfaction [26]. A study that specifically compares PMV and PPD index in people with medical protective clothing (medical isolation) and normal clothing (gown) has not been done so far. The results of the present study showed that there is a significant difference in the average index of the predicted vote and the percentage of dissatisfaction between the two groups of people wearing protective clothing (medical isolation) and normal clothing (gown), which indicates that the feeling of thermal discomfort is higher in people using the clothing. It is medically isolated, and after that, a higher percentage of people are dissatisfied with their thermal conditions.

In both types of coverings used by the treatment staff, the PMV index is high, but this index is higher in people with integrated insulated clothes, which can be caused by the impermeability and insulation of these clothes. In this study, the amount of moisture inside the clothes was determined. The prices of integrated insulated clothing are higher than those of overalls, which is the reason for the dissatisfaction of most people with integrated insulated clothing.

6.4 The intensity of perspiration felt

The use of integrated insulated clothes causes an additional load of heat on the body and causes the accumulation of moisture inside the clothes. Dewey’s study also showed that the feeling of thermal discomfort caused by personal protective equipment is one of the reasons for removing them during the work shift [27]. Lembo’s study also showed that protective clothing significantly increases the insulation level of clothing and this cause’s thermal discomfort [25]. The present study showed a difference in the perceived heat sensation in people with integral insulated clothing and people with overalls. There is no significance, but there is a significant difference in the amount of moisture felt on the skin and the pleasantness of the temperature conditions between the two groups. It is the cause of people’s dissatisfaction with the existing temperature conditions.

Considering that one of the results of the study is the high prevalence of skin complications caused by the use of personal protective equipment, it can be concluded that one of the causes of this issue can be the high amount of moisture accumulated due to sweating on the skin.

6.5 Mental workload

Mental workload perceived by nurses depends on different factors and conditions. During the Covid-19 epidemic, various studies were conducted on this topic. The results of these studies showed that the mental workload of nurses has increased during the outbreak of Covid-19 and the negative effects of workload on nurses and the organization can directly and indirectly affect the ability of nurses to provide patient care [28]. Asghari’s study also showed that health workers who were in contact with Covid-19 patients were exposed to more workload compared to people who had no contact with Covid-19 patients at work [29].

The present study, in line with the previous studies, shows the high mental workload in nurses when dealing with patients with covid-19, but the results also showed that the average mental workload in nurses using normal clothes (gowns) which in The care departments of non-covid patients were more active than those using medical isolation clothes, which could be due to the fact that the spread of covid-19 has caused concern among all nurses and people wearing coveralls due to the lack of assurance of high level protection. Against the disease, they suffered more mental burden than people with medical isolation clothes, and the fear of disease and contamination was more among them, which affected the factors related to mental burden. On the other hand, with the spread of the covid-19 disease, the number of nurses working in non-covid departments decreased due to the need of the care departments for covid-19 patients, and this caused an increase in the work pressure on nurses.

6.6 Blood oxygen

Various studies have been conducted on the effect of using personal protective equipment on blood oxygen levels. A number of these studies show a decrease in blood oxygen levels during the use of this equipment. Scarto et al.’s study showed a decrease in blood oxygen level during the use of FFP2 mask and personal protective equipment during oral and dental surgery [30]. Blood oxygen saturation decreases [31], which is contrary to the results of the present study. Studies have also shown that the use of personal protective equipment does not cause a significant decrease in blood oxygen level, or the decrease is very small. The study conducted by Vushtaş et al. shows this [32]. The present study, in line with Vushtash’s study, showed that the use of medical isolation clothes and gowns did not decrease the blood oxygen level, and there was no significant difference between the two groups in this regard. Considering that the present study was conducted after about a year and a half of the outbreak of the covid-19 disease, there has been a physiological adaptation in the use of personal protective equipment, which was revealed in the conversation with the nurses, as most of them stated that in At the beginning of the outbreak of the Covid-19 disease, they faced symptoms of low blood oxygen levels, but over time, these symptoms decreased and their blood oxygen levels returned to normal, and even when they feel that their blood oxygen levels have decreased over time. They return to their normal state less than before.

6.7 Deep temperature

Various studies have investigated the effect of using personal protective equipment on depth temperature. A study by Chang et al showed that after a work shift, core body temperature increased by 0.27 degrees among health care workers wearing specific personal protective equipment for protection against Covid-19, which can cause kidney damage [33]. The results of Liu et al.’s study regarding the effect of using different types of personal protective equipment on human thermal perception and physiological responses showed that medical protective clothing has an obvious blocking effect on heat exchange between humans and the environment [34]. That this problem can affect the increase in body temperature.

Contrary to previous studies, the present study showed that the use of medical isolation protective clothing and overalls increases the non-depth temperature and the measured depth temperature within the normal range, and a significant difference between these two groups in the average measured depth temperature was observed. Did not look the reason for this could be the adaptation of the nurses to the existing temperature conditions, and according to the statements of the nurses, in the first 2 to 3 months when they were forced to use additional protective equipment, the heat conditions caused by this equipment were more uncomfortable for them. After that, their discomfort has decreased. On the other hand, it should be kept in mind that with the spread of the Covid-19 disease, the air conditioning installed in nursing stations and nurses’ rest rooms has been improved, which can help in establishing body temperature balance.

6.8 Heart rate

Various studies show the impact of heart rate on the use of personal protective equipment. Choudhary et al.’s study reported a significant increase in physiological parameters including heart rate and oxygen saturation in conditions after removing personal protective equipment compared to the baseline [31] in Kolb et al.’s study on surgeons, in heart rate, blood pressure and some In other physiological and cognitive parameters, no significant difference was observed between the two types of personal protective equipment, which could be related to the age and experience of the studied surgeons and, as a result, lower stress [35]. The present study is in line with this study. It showed that the use of medical isolation clothes and normal clothes (gowns) had no effect on the measured average heart rate and the heart rate was within the normal range. The results also showed that there is no significant difference between the average heart rate in people using medical isolation clothes and gowns. This issue can be caused by the compromise of people with working conditions. Considering that the heart rate was measured only at the beginning and end of the desired time period and it was not possible to measure it during the performance of nurses’ duties due to existing limitations, this result can be studied further.

6.9 Physiological strain

Regarding the dependence of physiological strain index on heart rate and core temperature, since there was no significant difference between these two factors in people wearing medical isolation clothes and gowns. Also, the difference of this index is not significant in two groups and the average of this index in both groups is less than 2, which indicates that the load on the cardiovascular system is low.

6.10 Skin temperature

Various studies show the effect of using personal protective equipment on people’s feeling of warmth and body temperature. The study of Fernandez Mendez showed that the long-term use of personal protective equipment during cardiopulmonary resuscitation causes an increase in sweating and the feeling of heat and body temperature of people [36] the study of Masri et al shows the effect of using personal protective equipment on perceived thermal stress by individuals [37]. Unlike previous studies, the present study did not show an increase in body temperature when using personal protective equipment, and the average temperature recorded in both groups of people using medical isolation clothing and overalls is in the normal range. But in the comparison between the groups, the average skin temperature measured in people using medical isolation clothes is lower than people using overalls. This issue can be caused by more sweating of people wearing medical isolation clothes and as a result the skin gets cold.

6.11 Temperature and humidity inside the clothes

The present study showed that the average temperature inside the clothes in people wearing medical isolation clothes is lower than people wearing overalls, but the average humidity inside the medical isolation clothes is higher than the overalls. And there is a significant difference between the two groups in these two factors. The reason for the lower average temperature inside the medical isolation clothing can be due to the cooling effect of the humidity inside the clothing.

7 Conclusion

The results of the present study showed that the use of protective equipment for the whole body can cause thermal complications and skin complications in nurses, which can affect their health in the long term. The results also showed that the use of personal protective equipment can affect stress and thermal strain perceived by people and mental workload. Although the use of medical isolation clothes compared to normal clothes (gowns) can increase the level of protection against the disease of Covid-19, but the high humidity inside these clothes and the high weight of sweating by the users of these clothes should be taken into account. Clothes can have adverse effects on people’s health in the long run. Also, the results showed that in certain periods of time, people using medical isolation clothes and gowns tolerated very high temperature levels, which is also important to pay attention to. In such a way that the recorded temperature inside the clothes was more than 40 degrees Celsius. Even the recorded humidity inside the clothes was more than 60% for many periods of time, and this level of temperature and humidity can cause irreparable effects. As it became clear in the conversation with the nurses, enduring these conditions has caused a decrease in their motivation and an increase in their stress level, which requires more studies to investigate these effects.

In order to protect the health of the medical staff, paying special attention to the air conditioning and cooling systems of the nurses’ activity areas and their rest rooms can be effective. If possible, the nurses’ activity areas should be changed in rotation so that the nurses do not have to use the same type of protective cover for a long time. Increasing the number of nurses in departments with a high patient load can also be effective in reducing the workload of people.

7.1 Strengths and limitations of the study

One of the strengths of this study compared to other similar studies was that in most of the previous studies, only one aspect or limited aspects of the effects of personal protective equipment on human performance were investigated; however, in the present study, objective and subjective evaluations were performed simultaneously on people. Also, unlike similar studies, the present study was conducted on a larger volume of samples and this work was done in the real environment and without intervention in the existing conditions. With all these cases, there were limitations in conducting this study: firstly, conducting the study in the real environment causes that there are many interveners that are not under control, on the other hand, the number of people who died during the study due to the conditions created in the place where they were excluded from the study was high. Second, the cooperation rate of male nurses was very low, and this caused us to not be able to compare the two sexes, and thirdly, the investigated factors were measured in 2-hour intervals for each person, and each person was examined only for one day. would take Finally, due to the coordination of the results, the selected nurses have clothes of the same gender, have one type of mask, one type of head covering and eye protection, and one type of cover under protective clothing. Future studies need to investigate potential confounding factors in the relationship between wrist surface temperature and the effect of protective gloves and protective clothing, which would contribute to the technical robustness of the study.

Ethical approval

This study has been approved with the ethics code IR.SUMS.REC.1400.388 and Grant number 23082 in Shiraz University of Medical Sciences.

Informed consent

All participants provided informed consent prior to enrollment. No identifying information is presented in this work.

Conflict of interest

Not applicable.

Footnotes

Acknowledgments

This article is from the thesis of Ms. Fatemeh Asdollahi entitled “Investigation of the effect of the use of protective clothing on the thermal stress and mental workload of the staff in Iran during the covid-19 pandemic”. The authors would like to express their gratitude to the Vice-Chancellor of Research and Technology of Shiraz University of Medical Sciences for the financial support of the research and to the nurses working in partner hospitals who assisted in conducting this research.

Funding

This study was funded by Shiraz University of Medical Sciences.

Personal Protective Equipment.

Predicted Average Vote.

Predicted Percentage of Dissatisfied.

NASA Task Load Index.

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Coverage	Thermal symptoms
	Headache	Dizziness	Thirst	Vomit	Profuse sweating	Breathing hard	Dehydration	Fatigue
Medical isolation gown	49.28	27.14	60.00	4.28	46.42	46.42	48.57	72.14
Medical Gowns	58.12	23.75	47.50	3.12	35.00	31.25	38.12	68.75
P-value^*	0.125	0.50	0.03	0.59	0.04	0.007	0.06	0.52

Coverage	Parts of the body that have skin complications
	Face	Head	Neck	Hands	Legs	Waist	Chest	Abdomen
Medical isolation gown	52.85	13.75	22.14	45.00	29.28	12.85	15.71	3.75
Medical Gowns	38.75	11.87	16.25	39.37	24.37	7.50	8.75	1.87
P-value^*	0.01	0.65	0.19	0.32	0.33	0.12	0.06	0.36

Objective and subjective evaluation of the use of protective clothing on the thermal strain and mental workload of nurses during the Covid-19 pandemic

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1 Introduction and background

2 Methods

2.1 Determining the sample size

3 Tools

3.1 Subjective Evaluation Tools

3.1.1 Questionnaire of demographic characteristics

3.1.2 Questionnaire of heat symptoms caused by working conditions and environment

3.1.3 Questionnaire for assessing skin complications caused by the use of personal protective equipment

3.1.4 Thermal comfort questionnaire

3.1.5 NASA-TLX 4 mental load questionnaire

3.2 Objective Evaluation Tools

3.2.1 Temperature and humidity USB data logger

4.1 Collect objective data

4.2 Subjective data collection

4.3 The method of information extraction and statistical inference

5 Results

5.1 Findings from subjective evaluation

Table 4 Average predicted score of nurses with two different types of coverage (n = 300) Variable Mean ± SD Min Max P-value* Predicted Mean Vote (PMV) Medical isolation gown 1.99 ± 0.086 0 3 0.002 Medical Gowns 1.62 ± 0.081 0 3

5.2.1 Findings from objectively determining the PMV and PPD and its relationship with the type of clothing used

5.2.2 Findings from depth temperature measurement and its relationship with the type of clothing used

5.2.3 Findings from blood oxygen measurement and its relationship with the type of clothes worn

5.2.4 Findings from heart rate measurement and its relationship with the type of clothes worn

5.2.5 Findings from the average skin temperature and its relationship with the type of clothes worn

Table 7 Comparison of the average mental workload measured in nurses with two different types of coverage (n = 300) Variable Mean ± SD Min Max P-value* Mental workload Medical isolation gown 71.07 ± 13.35 31.66 100 0.009 Medical Gowns 74.69 ± 14.36 20 100

Table 8 The average physiological strain index measured in nurses with two different types of clothing (n = 120) Variable Mean ± SD P-value* Physiological strain index Medical isolation gown 1.33 ± 0.86 0.066 Medical Gowns 1.04 ± 0.83

6 Discussion

6.1 Experienced heat symptoms

6.2 Skin complications caused by the use of personal equipment

6.3 Average predicted vote and percentage of dissatisfaction

6.4 The intensity of perspiration felt

6.5 Mental workload

6.6 Blood oxygen

6.7 Deep temperature

6.8 Heart rate

6.9 Physiological strain

6.10 Skin temperature

6.11 Temperature and humidity inside the clothes

7 Conclusion

7.1 Strengths and limitations of the study

Ethical approval

Informed consent

Conflict of interest

Footnotes

Acknowledgments

Funding

References

Table 4
Average predicted score of nurses with two different types of coverage (n = 300)

Variable Mean ± SD Min Max P-value^*

Predicted Mean Vote (PMV) Medical isolation gown 1.99 ± 0.086 0 3 0.002

Medical Gowns 1.62 ± 0.081 0 3

Table 7
Comparison of the average mental workload measured in nurses with two different types of coverage (n = 300)

Variable Mean ± SD Min Max P-value^*

Mental workload Medical isolation gown 71.07 ± 13.35 31.66 100 0.009

Medical Gowns 74.69 ± 14.36 20 100

Table 8
The average physiological strain index measured in nurses with two different types of clothing (n = 120)

Variable Mean ± SD P-value^*

Physiological strain index Medical isolation gown 1.33 ± 0.86 0.066

Medical Gowns 1.04 ± 0.83