郑州市冬春季相对湿度和PM_(2.5)的关系

The Relationship Between Relative Humidity(RH)and PM_(2.5)During Winter and Spring of Zhengzhou

【目的】探究郑州市2019—2023年冬春季(11月至次年4月)PM_(2.5)浓度与相对湿度的关系,为开展城市PM_(2.5)监测和道路洒水作业提出建议。【方法】基于PM_(2.5)浓度及湿度、风速、降水、气温等气象观测数据,在STATA软件中建立多元逻辑回归模型,设定参照组,分析PM_(2.5)随相对湿度的变化趋势。【结果】2019—2023年冬春季郑州市PM_(2.5)均值由72.41μg/m^(3)降为61.42μg/m^(3),降幅为15.2%。在相对湿度低于80%时,随着相对湿度增大,PM_(2.5)出现在较高浓度区间的概率也增大,且该结果具有统计显著性。【结论】空气中的水分会促进PM_(2.5)前体物生成二次颗粒物,并导致细颗粒物吸水进而增加重量,但相对湿度过高时可能由于降雨冲刷而导致PM_(2.5)浓度下降。建议在进行PM_(2.5)监测时充分剔除湿度对测量值的影响,在道路洒水作业前也要全面考虑气象条件及大气污染状况。

[Purposes]By exploring the relationship between PM_(2.5) and RH during winter and spring(November to April of the following year)of Zhengzhou from 2019 to 2023,suggestions for conducting PM_(2.5) monitoring and road watering operations were proposed.[Methods]Based on PM_(2.5) and meteorological data including RH,wind speed,precipitation,and temperature,the logistic multiple model was performed in STATA after setting the base group to analyze the trend of PM_(2.5) in accordance with RH.[Findings]The average concentration of PM_(2.5) reduced from 72.41μg/m^(3) to 61.42μg/m^(3),with a decrease of 15.2%.When RH was below 80%,the probability of PM_(2.5) falling in a larger concentration range increased with the growth of RH,which was of statistical significance.[Conclusions]Moisture in the air would cause PM_(2.5) precursors to form secondary particles and lead the fine particles to absorb water,which both contributed to the aggravation of air pollution.However,extremely high level of RH might result in rainfall which would reduce PM_(2.5).It is suggested that the influence of RH should be fully eliminated during PM_(2.5) monitoring process,and meteorological conditions and air pollution conditions should be sufficiently considered before road watering operations.