Acute effects of particulate matter and black carbon on peak expiratory flow in a panel of schoolchildren residents in Tangara da Serra, Brazilian Amazon

摘要

Background: Panel studies have revealed adverse effects of air pollution on children's health due to biomass burning. The Brazilian Amazon has been marked by regular forest fires in the dry season during which high concentrations of air pollutants are frequent and long-lasting. Aim: To estimate the effect of current levels of air pollution in the Amazonian dry season on Peak Expiratory Flow (PEF). Methods: Panel study with 234 schoolchildren aged 6 to 15 years, living in the municipality of Tangara da Serra, Mato Grosso State, Brazil. PEF was measured daily in the dry season of 2008. Excluding weekends and holidays, the total number of study days was 53. All together there were 11198 PEF measures. Mixed effect models and a unified model approach repeated for every child were applied. Both model approaches regarded time trend, temperature, humidity, and subject characteristics. Inhalable particulate matter (PM10), fine particulate matter (PM2.5), and Black Carbon (BC) effects were estimated considering the 24-hour exposure lagged by 1 to 5 days and the averages of 2 or 3 consecutive days. Polynomial distributed lag models (PDLM) were also applied. Results: The analyses pointed to reductions on PEF for increases of 10 units of pollutants. For PM10, the reductions varied from 0.15 (CI95%: -0.29; -0.01) to 0.25 l/min (CI95%: -0.40; -0.10). For PM2.5, they ranged from 0.46 (CI95%: -0.86 to -0.06) to 0.54 l/min (CI95%:-0.95; -0.14). As for BC, the reduction was about 0.014 l/min. As regards PDLM, adverse effects were obtained for the current day until 5 past days. The sum of effects for PM10, corresponded to a PEF reduction of 0.31 l/min (CI95%: -0.56; -0.05). These associations were stronger for children between 6 and 8 years old. Conclusion: Reductions on PEF were associated with air pollution, mainly for lagged exposures of 3 to 5 days and for younger children.