Coarse Fraction Particle Matter and Exhaled Nitric Oxide in Non-Asthmatic Children

Coarse particle matter, PM(coarse), is associated with increased respiratory morbidity and mortality. The aim of this study was to investigate the association between short-term changes in PM(coarse) and sub-clininal airway inflammation in children. Healthy children aged 11 years from two northern Swedish elementary schools underwent fraction of exhaled nitrogen oxide (FENO) measurements to determine levels of airway inflammation twice weekly during the study period from 11 April–6 June 2011. Daily exposure to PM(coarse), PM(2.5), NO(2), NOx, NO and O(3) and birch pollen was estimated. Multiple linear regression was used. Personal covariates were included as fixed effects and subjects were included as a random effect. In total, 95 children participated in the study, and in all 493 FENO measurements were made. The mean level of PM(coarse) was 16.1 μg/m(3) (range 4.1–42.3), and that of O(3) was 75.0 μg/m(3) (range: 51.3–106.3). That of NO(2) was 17.0 μg/m(3) (range: 4.7–31.3), NOx was 82.1 μg/m(3) (range: 13.3–165.3), and NO was 65 μg/m(3) (range: 8.7–138.4) during the study period. In multi-pollutant models an interquartile range increase in 24 h PM(coarse) was associated with increases in FENO by between 6.9 ppb (95% confidence interval 0.0–14) and 7.3 ppb (95% confidence interval 0.4–14.9). PM(coarse) was associated with an increase in FENO, indicating sub-clinical airway inflammation in healthy children.