Comparison of Hourly PM2.5 Observations Between Urban and Suburban Areas in Beijing, China.

Ling Yao,Xiafang Yue,Jia Du,Ning Lu,Cundong Yang

doi:10.3390/ijerph121012264

Abstract

Hourly PM2.5 observations collected at 12 stations over a 1-year period are used to identify variations between urban and suburban areas in Beijing. The data demonstrates a unique monthly variation form, as compared with other major cities. Urban areas suffer higher PM2.5 concentration (about 92 μg/m3) than suburban areas (about 77 μg/m3), and the average PM2.5 concentration in cold season (about 105 μg/m3) is higher than warm season (about 78 μg/m3). Hourly PM2.5 observations exhibit distinct seasonal, diurnal and day-of-week variations. The diurnal variation of PM2.5 is observed with higher concentration at night and lower value at daytime, and the cumulative growth of nighttime (22:00 p.m. in winter) PM2.5 concentration maybe due to the atmospheric stability. Moreover, annual average PM2.5 concentrations are about 18 μg/m3 higher on weekends than weekdays, consistent with driving restrictions on weekdays. Additionally, the nighttime peak in weekdays (21:00 p.m.) is one hour later than weekends (20:00 p.m.) which also shows the evidence of human activity. These observed facts indicate that the variations of PM2.5 concentration between urban and suburban areas in Beijing are influenced by complex meteorological factors and human activities.

Highlights

Atmospheric particulate matter (PM), especially PM less than 2.5 μm in aerodynamic diameter (PM2.5), has recently been a concern of scientists and the public due to its quantified effects on human health, such as increased morbidity and mortality from cardiovascular and respiratory diseases, and even death rates [1,2,3,4]
Along with the rapid economic development, the average concentration of PM2.5 in Beijing increased from 70–90 μg/m3 between 1989 and 1990 to 70–100 μg/m3 in 2000–2010 [9,10,11], about 2–3 times higher than the National Air Quality Standard (NAQS) and 5–6 times higher than the air quality guideline (AQG) recommended by the World Health Organization [12]
It is estimated that approximately 174 days of the daily PM2.5 concentrations exceeded the daily PM2.5 standard of NAQS (75 μg/m3) during the 1-year research period

Summary

Introduction

Atmospheric particulate matter (PM), especially PM less than 2.5 μm in aerodynamic diameter (PM2.5), has recently been a concern of scientists and the public due to its quantified effects on human health, such as increased morbidity and mortality from cardiovascular and respiratory diseases, and even death rates [1,2,3,4]. Several studies carried out in Beijing have demonstrated the relationships between high PM2.5 concentration and mortality and morbidity [5,6,7,8]. It has been proved that high PM2.5 concentration leads to the occurrence of haze [13,14]. Sensitivity test shows that the mass concentration threshold of PM2.5 to cause haze occurrence was about μg/m3 when the relative humidity was 70% in Beijing [15]. Lower visibility occurred mainly in the urban areas of Beijing, where the number of haze days showed an increasing trend [16]. Identifying the spatial and temporal variations in PM2.5 concentration would have immense significance to make effective pollution control strategy [17]

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