Exposure to current levels of PM2.5 resulting from biomass burning is a risk factor to human health in the Amazon region.
To investigate the association between PM2.5 and lung function in schoolchildren in the Brazilian Amazon stratified by morning and afternoon shifts.
A panel study with a sample of 309 schoolchildren from 6 to 15 years old. Repeated measures of peak expiratory flow (PEF) were collected during 112 days. Daily measurements of PM2.5, temperature, humidity as well as respiratory symptoms were recorded. For the statistical analysis, the exposure measure was the average of PM2.5 in the morning or afternoon. The analysis was based on random effects models. The effects were evaluated considering the air pollution levels on the current day, 1 to 3 days lag and cumulative effects of 2 and 3-days.
Averages of PM2.5 ranged from 3,3 to 120,8 μg/m3. The working model consisted of temporal trends, temperature and humidity lagged by 2-days, fitted via quadratic parametric splines with random coefficients. Further, the occurrence of respiratory symptoms such as cough, running nose, headache, tearing and visit to the hospital were regarded using random effects. Moreover the results were adjusted for age and asthma diagnosis (asthmatic and non-asthmatic). The effects of air pollution on lung function were significant only for the afternoon shift. For an increase of 10 μg/m3 of PM2.5 on the same day, the PEF average decreased 0,45 l/min. The cumulative effects of 2-days and 3-days decreased 0,44 l/min and 0,40 l/min, respectively.
Exposure to current levels of fine particulate matter in the Amazon region, caused by biomass burning, is associated with reductions in lung function of schoolchildren, especially those studying in the afternoon.