Study On The Impact Of Weather Types On Air Pollution And Health Risks

Air pollution is not only affected by pollution emissions,but also closely related to weather conditions.Meteorological conditions affect the diffusion,transformation and removal of pollutants in the atmosphere.Also,both meteorological conditions and air pollution are factors that affect population mortality and morbidity.However,the mixed effects of various meteorological variables and air pollution or meteorological variables are very complex,and it is difficult to separate the health effects of different parameters,and little is known about the health risks of atmospheric pollutants in the context of different weather patterns.Progressive classification of weather conditions and research on the health risks of pollutants under common weather types can help understand the characteristics of urban weather and air pollution,as well as predict the atmospheric pollution conditions under different meteorological conditions.And it can also help analyze the simultaneous response of people to a combination of meteorological and pollution variables,and provide theoretical basis for pollution prevention and health warning of specific pollutants.This study takes Nanjing as an example.Spatial Synoptic Classification（SSC）is used to classify the weather types of Nanjing into Dry Polar（DP）,Dry Moderate（DM）,Dry Tropical（DT）,Moist Polar（MP）,Moist Moderate（MM）,Moist Tropical（MT）,Moist Tropical plus（MT+）and transition type（TR）.Humid and hot（including MT and MT+）weather types appear most frequently and concentrated in summer.In this study,the six basic pollutants SO₂、NO₂、PM₁₀、PM_2.5、CO and O₃ specified in the ambient air quality standard were selected as the research objects to analyze the concentration characteristics of different pollutants under various weather types.It was found that the average concentration of each pollutant in dry and sunny weather conditions（DM,DP,DT）was higher than that in humid conditions（MM,MP,MT）.In order to further study the influence of meteorological factors on the concentration of pollutants,grey correlation analysis was used to calculate the correlation between six pollutants and each meteorological factor.Of the four seasons,meteorological conditions have the greatest impact on pollutant concentrations in winter.For the five pollutants other than O₃,the order of influence of meteorological factors is air pressure,wind speed,temperature,cloud cover,and dew point.The O₃ concentration is most affected by temperature.In addition,this study defines extreme pollution episodes as the concentration of each pollutant exceeding the 95%quantile,and studies the relationship between extreme pollution situations and weather types by defining the extreme pollution risk ratio.Results show that extreme pollution episodes often occur in relatively dry and cloud-free weather types in Nanjing.Specifically,extreme pollution episodes are more likely to occur at temperatures of 5～10°C,dew point temperatures of 0～5°C,pressures of 1020～1025 h Pa,clouds of 0～2,and wind speeds of 2～3 m/s.In this study,a distributed lag nonlinear model was used to study the risk of total deaths、deaths from cardiovascular disease and respiratory disease of SO₂、NO₂、PM₁₀、PM_2.5、CO and O₃ in Nanjing.The results show that with the increase in the concentration of pollutants,the risk of total death,death from cardiovascular disease and respiratory disease gradually increases,and has a lag effect.Within 0 to 6 days of lag,the cumulative risk of various types of death increases first and then decreases,which usually reaches its maximum in about 3～5 days lag.Different pollutants have different death risks under different weather types.For total deaths,the total death risks for SO₂,NO₂,and PM₁₀ are highest in MP weather types,CO and PM_2.5are in DP,and O₃ is highest in DM types;for cardiovascular Disease death,PM₁₀,PM_2.5,NO₂ in DP type,SO₂ in MP type,O₃ is highest in DM type;for respiratory diseases,SO₂,PM_2.5 in DP weather type,PM₁₀ and NO₂ are in MP type,CO is in MT type,and O₃ is highest in MT+type.In general,pollutants other than O₃ have a higher risk of death in cold weather than in hot weather.In addition to the classification of weather,this study also defines extreme weather scenarios.According to the existing weather data,based on the proportional threshold index,the 10th or 90th percentile of each meteorological parameter is taken as the threshold.Extreme weather is defined as above 90 percentile or below 10 percentile.A total of eight extreme weather conditions including extreme high temperature,low temperature,high pressure,low pressure,strong wind,calm wind,cloudy,and few clouds were defined.The percentages of death risk of the population were increased than usual under each extreme weather situation.In extreme weather such as high temperature,low temperature,high pressure,and low pressure,the risk of total death,cardiovascular disease death,and respiratory disease death is significantly increased.Therefore,in extreme weather,more attention should be paid to pollution control and crowd protection.On this basis,the conditions that belong to extreme weather for more than three consecutive days are further defined as persistent extreme weather events.The relationship between deaths of various pollutant concentrations under continuous extreme weather events is studied,and the results show the correlation between pollutants and total deaths.The highest degree was associated with death from respiratory diseases.In summary,this study analyzes the effects of weather types and meteorological factors on pollutant concentrations,compares the death risk of pollutants under different weather types,and the impact of extreme weather conditions on death risk.It helps relevant departments to formulate hierarchical pollution prevention and control measures based on the concentration of pollutants and health risks under different weather types.At the same time,early warnings of pollutant health risks can be issued in combination with weather conditions,and early warning information can be released in a timely manner in conjunction with air quality monitoring data when weather conditions that are likely to cause heavy pollution appear,to guide the public in health protection.Provide theoretical basis for prevention and control of air pollution,health warning of pollutants and scientific protection.