Ambient levels and temporal variations of PM_2.5 and PM₁₀ at a residential site in the mega-city, Nanjing, in the western Yangtze River Delta, China

Abstract

The deteriorating air quality in eastern China including the Yangtze River Delta is attracting growing public concern. In this study, we measured the ambient PM₁₀ and fine PM_2.5 in the mega-city, Nanjing at four different times. The 24-h average PM_2.5 and PM₁₀ mass concentrations were 0.033–0.234 and 0.042–0.328 mg/m³, respectively. The daily PM₁₀ and PM_2.5 concentrations were 2.9 (2.7–3.2, at 95% confidence interval) and 4.2 (3.8–4.6) times the WHO air quality guidelines of 0.025 mg/m³ for PM_2.5 and 0.050 mg/m³ for PM₁₀, respectively, which indicated serious air pollution in the city. There was no obvious weekend effect. The highest PM₁₀ pollution occurred in the wintertime, with higher PM_2.5 loadings in the winter and summer. PM_2.5 was correlated significantly with PM₁₀ and the average mass fraction of PM_2.5 in PM₁₀ was about 72.5%. This fraction varied during different sampling periods, with the lowest PM_2.5 fraction in the spring but minor differences among the other three seasons.

Keywords:

• Particulate matter
• temporal variation
• weekend effect
• western YRD region

Acknowledgments

Funding for this study was supported by China Postdoctoral Science Foundation (No. 2013M531322), the National Natural Science Foundation (41301554) and the Jiangsu Natural Science Foundation (BK20131031). We thank anonymous reviewers for valuable comments.