Previous studies have reported sources of particle number pollution in urban air, but have not evaluated relationships between respiratory health and these sources. We compared, among children with asthma or allergies, the associations of spirometric lung functions with increased exposure to source-specific versus size-segregated particle number concentrations (PNC). Hourly measurements of PNC were acquired from the aerosol Supersite in New Taipei, Taiwan. Spirometry (FVC, FEV1, and FEF) was recorded monthly for 59 children with asthma or allergies at five schools during 2007-2008. After co-pollutant adjustment for ozone, we found a 0.21 and 0.17 L decrease in FVC [95% confidence interval (CI): -0.35, -0.06 L] and FEV1 (95% CI: -0.32, -0.03 L), respectively, with an interquartile range increase (1879.7#/cm(3)) in secondary aerosol contribution observed on the previous day. In addition, we found no significant associations of FVC with accumulation mode (0.1 μm<aerodynamic diameter<2.5 μm) PNC. Our findings suggest that PNC of secondary origin is most responsible for pollution-related respiratory effects among children living in urban Taipei. Studies that rely on exposure to size-segregated PNC may underestimate PM health impacts.
Keywords: Air pollution; Children; Lung function; Particle number; Source apportionment.
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