Variation of Particulate Matter and Its Correlation with Other Air Pollutants in Xi`an, China

Abstract

IntroductionWith improved living conditions, people gradually pay more and more attention to the problems which were caused by air pollution [1]. The concentrations of particulates and gassy pollutants in the atmosphere were all seriously exceeded. Such as PM 2.5 , PM 10, sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), carbon monoxide (CO), and ozone (O 3 ) [2]. They would not only lead to a serious decline in atmospheric visibility, but also they would cause many problems to people's travel and transport at the same time [3]. PM 2.5 was usually referred to as particulate with an average aerodynamic diameter of less than 2.5 μm, and they did not settle automatically [4]. PM 2.5 was more likely to carry more viruses or bacteria with its small particle sizes and large specific surface area. It would bring different degrees of harm to human health, even death [5][6][7].

Concentration Characteristics and Correlations with Other Pollutants of Atmospheric Particulate Matter as Affected by Relevant Policies

“…Particles of sizes of 1.0~2.5 µm accounted for about 0.235%, 0.281%, 0.282%, 0.173%, and 0.174%, respectively, with the proportion decreasing by 0.061%. However, the proportion of particles of sizes above 2.5 µm was relatively small; this is consistent with the conclusions given in the literature, which verifies the validity of the results of this paper [22,23]. The changes in the 5 years considered were relatively insignificant for particles of sizes larger than 2.5 µm, but there was still a trend of decreasing concentrations.…”

“…The concentrations in winter were 1.42 times higher than those in spring, 1.63 times higher than those in autumn, and 2.81 times higher than those in summer. Overall, it was observed that the concentrations of particulate matter were the highest in winter and the lowest in summer, which is consistent with the literature [22].…”

“…The main reason was the demand for heating in winter, which leads to an increase in the concentrations of particulate matter. Another reason was the influence of vertical movement in the atmosphere, which is not conducive to the spread of particles [22,23]. As a result, the concentrations of particulate matter reached the maximum at around 11 o'clock at night.…”

“…Current research on air pollutants in China is also limited to certain areas, such as Nanjing [19], Yunnan [20], Beijing [21], and other places; meanwhile, there have been relatively few recent studies on northwest inland cities. In addition, there is a significant difference between the north and the south in China, and the particle concentration distributions in different regions show even greater differences [22]. Many different countries and regions around the world have introduced stricter control measures and control methods for monitoring pollutants in the atmosphere and have also strengthened energy adjustment measures and increased implementation efforts in recent years.…”

Comparison of the Application of Three Methods for the Determination of Outdoor PM2.5 Design Concentrations for Fresh Air Filtration Systems in China

“…In addition, PM 2.5 in the atmosphere might cause some diseases related to human lung disease, cardiovascular disease, etc. [ 4 , 5 , 6 , 7 , 8 ]. However, people spend as much as 80–90% of their time indoors [ 9 ], and the quality of the indoor environment was the most important to us.…”