Personal exposure to fine particles (PM_2.5) and respiratory inflammation of common residents in Hong Kong

Background: Given the lack of research on the personal exposure to fine particles (PM2.5) in Hong Kong, we examined the association between short-term personal exposure to PM2.5and their constituents and inflammation in exhaled breath in a sample of healthy adult residents. Method: Forty-six participants underwent personal PM2.5monitoring for averagely 6 days to obtain 276 samples. Fractional exhaled nitric oxide (FeNO), a biomarker of inflammation in exhaled breath, was measured at the end of each 24-h personal monitoring. PM2.5chemical constituents, including organic carbon, elemental carbon, 16 polycyclic aromatic hydrocarbons (PAHs), and 6 phthalate esters, were speciated from the personal samples collected. A mixed-effects model was used to estimate the association of PM2.5and their constituents with FeNO. The comparison was also made with parallel analyses using ambient concentrations. Results: Personal exposures to PM2.5(28.1 ± 23.3 μg/m3) were higher than the ambient levels (13.3 ± 6.4 μg/m3) monitored by stations. The composition profile and personal-to-ambient concentration ratio varied among subjects with different occupations. An interquartile range (IQR) change in personal exposure to PM2.5was positively associated with 12.8% increase in FeNO (95% confidence interval, CI: 5.5–20.7%), while nil association was found for ambient PM2.5. Among the constituents measured, only the carcinogenic PAHs were significantly associated with 12% increase in FeNO responses (95% CI, 0.0–25.6%). Conclusion: In conclusion, our study provides the first understanding about personal exposure to PM2.5and possible sources in Hong Kong. The results also showed that personal exposure to PM2.5and c-PAHs were linked to increased FeNO levels among healthy adults.