Domestic airborne fine particulate matter exposure and asthma control among children receiving inhaled steroid treatment

The aims of the present study were to measure domestic PM_2.5 exposure and explore relationships with indices of asthma severity and control in children prescribed inhaled corticosteroids (ICSs). Disease severity was determined by questionnaire and spirometry. Asthma control was assessed by 5-day peak flow variability (PFV) and children's asthma control test (CACT) on the 1st and 5th day of peak flow testing. Concentrations of PM_2.5 were measured over a 24-h period. Twenty-two children were recruited, mean age 11.0 years. Across the 22 homes the median time weighted average (TWA) PM_2.5 concentration (range) was 7.4 μg/m³ (2.0–150.0) and was significantly higher in the seven homes where smoking was reported (24.0 μg/m³) than non-smoking homes (6.0 μg/m³), p=0.001. There was a positive association between TWA PM_2.5 and PFV (rho = 0.55, p = 0.015, n = 19) and a negative association between TWA PM_2.5 and CACT (rho = − 0.56, p = 0.010, n = 20). TWA PM_2.5 exposure was not related to indices of asthma severity. Peak PM_2.5 concentration was not associated with any outcome. This exploratory study suggests that even at relatively low concentrations, there is an exposure–response relationship between increasing indoor air PM_2.5 concentrations and poorer asthma control in children prescribed ICSs.