Particulate Exposure in Asthmatic Kids (PEAK); Fine and ultrafine particle exposures among inner-city children

摘要

The adverse effects of particulate matter (PM) air pollution, particularly fine particles (PM_(2.5), particles with diameter less than 2.5 μm), on respiratory health are well known. However, recent toxicological studies suggest the potential for stronger association of the ultrafine (UFP, particles with diameter less than ～0.1 μm) portion of PM exposure with respiratory health. Despite the known challenges of assessing their exposure, understanding the health effects of UFP is a critical step to developing interventions aimed at reducing the harmful effects of PM exposure. The PEAK study aims to determine the association of particle size, microenvironment and peak exposure with respiratory effects in inner-city children with asthma. We examined personal UFP and PM_(2.5) exposures in a cohort of 15 asthmatic children aged 10-17 at high temporal and spatial resolution. Each child was followed for 7 days with 4 days of continuous monitoring of UFP (expressed as LDSA, lung-deposited surface area), PM_(2.5) and geographic location via GPS using a backpack. On days 2-5, spirometry and exhaled NO measurements were done and biomarker (urinary LTE4) was collected. Daytime and nighttime asthma symptom were obtained via text message from the child or parent. Highly variable exposure to UFP (1-hr mean: 49 μm~2/cm~3; range: 1-1413 μm~2/cm~3) and PM_(2.5) (1-hr mean: 23 μg/m~3; range: 1-377 μg/m~3) with weak correlation (R~2 < 0.3) were observed. Day-to-day and within-day variability were large for both UFP and PM_(2.5) with mean coefficients of variation of 213% and 286%, respectively. Asthma symptoms, mostly mild and moderate, were observed in 22% of the nights and 27% of the days. Both UFP and PM_(2.5) exposures showed high peaks with large day to day and between-day variabilities. The weak correlation between the two exposure metrics demonstrates the value of measuring both. By the end of this study we will be able to investigate the association between acute exposure to PM and asthma symptoms.