An exploration of meteorological effects on PM2.5 air quality in several provinces and cities in Vietnam

Linking meteorology and air pollutants is a key challenge.The study investigated meteorological effects on PM_(2.5)concentration using the advanced convergent cross mapping method,utilizing hourly PM_(2.5)concentration and six meteorological factors across eight provinces and cities in Vietnam.Results demonstrated that temperature(ρ=0.30)and radiation(ρ=0.30)produced the highest effects,followed by humidity(ρ=0.28)and wind speed(ρ=0.24),while pressure(ρ=0.22)and wind direction(ρ=0.17)produced the weakest effects on PM_(2.5)concentration.Comparing theρvalues showed that temperature,wind speed,and wind direction had greater impacts on PM_(2.5)concentration during the dry season whereas radiation had a more influence during the wet season;Southern stations experienced larger meteorological effects.Temperature,humidity,pressure,and wind direction had both positive and negative influences on PM_(2.5)concentration,while radiation and wind speed mostly had negative influences.During PM_(2.5)pollution episodes,there wasmore contribution ofmeteorological effects on PM_(2.5)concentration indicated byρvalues.At contaminated levels,humidity(ρ=0.45)was the most dominant factor affecting PM_(2.5)concentration,followed by temperature(ρ=0.41)and radiation(ρ=0.40).Pollution episodes were pointed out to be more prevalent under higher humidity,higher pressure,lower temperature,lower radiation,and lower wind speed.Theρcalculation also revealed that lower temperature,lower radiation,and higher humidity greatly accelerated each other under pollution episodes,further enhancing PM_(2.5)concentration.The findings contributed to the literature on meteorology and air pollution interaction.

Gaseous pollutant transport from an underground parking garage in a Mediterranean multi-story building—Effect of temporal resolution under varying weather conditions

Indoor air dynamics and quality in high density residential buildings can be complex as it is affected by both building parameters,pollution sources,and outdoor meteorological conditions.The present study used CONTAM simulations to investigate the intra-building transport and concentration of an inert pollutant continuously emitted from an underground garage of a 15-floor building under moderate Mediterranean weather.The effects of outdoor meteorological conditions(air temperature,wind speed and direction)on indoor distribution of the emitted pollutant was tested under constant conditions.The importance of using actual transient meteorological data and the impact of their temporal resolution on calculated concentrations and exposure levels were also investigated.Vertical profiles of air exchange rate(AER)and CO concentration were shown to be sensitive to indoor-outdoor temperature difference,which controls the extent of the stack effect and its importance relative to wind effect.Even under constant conditions,transient mode simulations revealed that the time needed for pollutant distribution to reach steady state can be quite long(>24h in some cases).The temporal resolution(Ih vs.8h)of the meteorological data input was also found to impact calculated exposure levels,in an extent that varied with time,meteorological conditions and apartment position.