[Response of Human Respiratory Height PM2.5 Variation Characteristics to Meteorological Factors During Winter Haze Days in Beijing]

Abstract

In order to investigate the influence of meteorological factors on the variation characteristics of PM_2.5 in Beijing. According to the survey of PM_2.5 mass concentration in height of human respiration, humidity, the direction of the wind, wind speed and temperature. Using the methods of correlation analysis and nonlinear regression analysis, the effects of meteorological factors on the formation and variation of PM_2.5 mass concentration in light and moderate air pollution days and heavy pollution were discussed respectively. The results showed that:① On mild to moderate pollution days, if the temperature was low, the daily average wind speed was low, the humidity was high, then the humidity was the decisive influencing factor of PM_2.5 mass concentration; if the temperature, wind speed and humidity were all high, then the variation of PM_2.5 mass concentration was influenced by the combined action of these three; when the temperature, humidity and wind speed were all low, then the PM_2.5 mass concentration was mainly affected by the first two factors. This suggested that changes in the height of the human respiration PM_2.5 mass concentrations were extremely sensitive to small changes in meteorological factors; ② During the process of air quality turning from good to heavily polluted, the accumulation of PM_2.5 mass concentration was mainly due to the weak air turbulence, coupled with the high humidity, in addition, the northwest wind and northeast wind were larger during the daytime but the duration was shorter, while the southeast and southwest wind speed at night was lower with longer duration, which was conducive to pollutant accumulation;③ Short-term low amount of snow decreased the temperature and increased the air humidity, which not only could not reduce the PM_2.5 mass concentration, but rather increased it by 72%, resulting in the jump phenomenon of particle concentration; ④ When the wind speed reached up to 2.0 m·s^-1 and lasted for two hours, the local PM_2.5 mass concentrations could be reduced to some extent, but it could not completely change the air quality situation. Only when the wind speed was greater than 3.5 m·s^-1 and lasted for more than 4 hours, the fine particulate matter in the air could be quickly diffused and the air quality was changed from heavy pollution to excellent.

Keywords: Beijing; PM2.5; human respiratory height; meteorological factors; polluted days.