Characteristics of the Spatial and Temporal Variations of Ambient PM2.5 Concentration at Kaohsiung City

摘要

The study analyzed the hourly and daily trends of PM2.5 concentration and summarized the spatial change in PM2.5 concentration as well as locations of the concentration hot spots based on data of PM2.5 concentration, wind speed, and wind direction collected at the air quality monitoring stations in 2010 at Kaohsiung City, Taiwan. Results from the correlation analysis of PM2.5 concentration suggest that for short-term (1-hr), PM2.5 concentration could be easily affected by pollution sources around the monitoring stations, due to the atmospheric dispersion, the trends of long-term concentration change among stations were similar (24-hr). The average annual PM2.5 concentration at Kaohsiung City was 41 μg/m~3, and the annual over-standard rate was 13.08% compared with the alert concentration value of 65 μg/m~3. The average 24-hr PM2.5 concentration was the lowest in summer (23 μg/m~3) but the highest in winter (62 μg/m~3). Concentration change was also the greatest in winter, and nearly 40% of the winter time the concentration was over-standard. Results of this study suggest that higher PM2.5 concentration would mainly happen with the winter monsoon (north wind), while lower PM2.5 concentration would mainly happen with the summer monsoon (southwest wind). Furthermore, Daliao and Linyuan monitoring stations at Kaohsiung City are the hot spots with the highest concentration. The results also suggest that the environmental agency should further assess influences from these high PM2.5 concentration hot spots on local people and formulate effective strategies for pollution emission control.