| Air pollution has become a serious problem in developing countries like China and Pakistan.There are two major reasons for this situation:rapid industrialization and lack for restrictions and regulations on emissions.Therefore,it would not be wrong to say that pollution from natural and manmade sources is posing a great threat to the quality of lif’e,and this situation is getting worse with every passing day.This study is motivated to analyze and monitor the current levels of air pollutants in Dalian-China and Faisalabad-Pakistan at present.The data collected during this study represents the ambient air quality of two densely populated and industrialized cities,belonging to two separate countries.The major focus has been given to the assessment of particulate matter(PM2.5 and PM10),sulphur dioxide（SO2）,nitrogen dioxide（NO2）and carbon monoxide（CO）concentrations in the selected cities.Those concentrations were evaluated from different stations,at each city,for a period of one year（2013）.Concentrations of the five air pollutants(PM2.5,NO2,SO2,CO and PM10)were used to develop the model for air quality assessment;the prediction model was developed by using the Artificial Neural Networks（ANNs）.Finally,the assessment of air quality of both cities was made by comparing the data with the four different regional standards（i.e.,NEQS[National Environmental Quality Standards],Pakistan;NAAQS[National Ambient Air Quality Standards],United State Environmental Protection Agency;CNAAQS[China National Ambient Air Quality Standards],China;and WHO[World Health Organization]）.（1）The current study was conducted to check PM2.5 and PM10 concentrations in Dalian and Faisalabad.The PM2.5 concentration in Faisalabad was in the 22-49μg/m3 range（average being 36.5 μg/m3）,whereas PM10 varied from 109 to 164.3 μg/m3（with an average of 148.3μg/m3）.The PM2.5 concentrations in Dalian varied from 5.5 to 93.3 μg/m3（average of 29.1μg/m3）,whereas PM10 values varied from 10.5 to 101.1 μg/m3（average being 45.9 μg/m3）.The average PM2.5 concentrations in Faisalabad were higher in winter than in summer,but overall concentrations were significantly different in both the seasons;however,the variations were considerably higher in Dalian compared to Faisalabad.On average,Faisalabad showed more PM concentrations compared to Dalian（even higher than permissible limits set by NEQS and USEPA）;on the other hand,the values representing Dalian were within the limits set by CNAAQS and WHO.（2）A comparative study was performed in both the cities to evaluate NO2,SO2 and CO concentrations in ambient air.The NO2 concentration in Faisalabad varied from 185-262 μg/m3,while it was in 44-133 μg/m3 range in Dalian.The SO2 concentration was found in the range of 66-190 μg/m3 and 56-128 μg/m3 in Faisalabad and Dalian,while CO varied from 5.4-22.3 mg/m3 and 0.3-2.8 mg/m3,respectively.The annual average NO2,SO2 and CO concentrations were below the permissible limits in Dalian;however,the measured values were considerably higher in Faisalabad.（3）The calculated concentrations of NO2,SO2 and CO in Faisalabad from ANNs model were 80 μg/m3,120 μg/m3 and 10 mg/m3,respectively;and 76 μg/m3,116 μg/m3 and 9.3 mg/m3,respectively,from field observations.The calculated concentrations of NO2,SO2 and CO in Dalian from ANNs model were 58 pg/m3,108 μg/m3 and 9.1 mg/m3,respectively;and 52 μg/m3,102 μg/m3 and 8.8 mg/m3,respectively,from field observations.The calculated concentrations of PM10 andPM2.5 in Faisalabad from ANNs model were 151.4 μg/m3,53.6 μg/m3,respectively;and 144 μg/m3 and 48 μg/m3,respectively,from field observations.The calculated concentrations of PM10 and PM2.5 in Dalian from ANNs model were 105.7 μg/m3,45.4 μg/m3,respectively;and 101.1 μg/m3 and 44.4 μg/m3,respectively,from field observations.The annual average concentrations of PM2.5 and PM10 in Faisalabad were higher than Pakistan’s NEQS（35 μg/m3 and 150 μg/m3）and USEPA（35 μg/m3 and 150 μg/m3）,whereas within the limits set by CNAAQS（75 μg/m3 and 150 μg/m3）and WHO（75 μg/m3 and 150μg/m3）.However.Dalian city’s PM concentrations were within the permissible limits.In Dalian,on average,it was observed that the NO2,SO2 and CO concentrations remained within the permissible limits set by NEQS（80 μg/m3,120 μg/m3 and 10 mg/m3）,USEPA（100μg/m3,120 μg/m3 and 10 mg/m3）and CNAAQS（80 μg/m3,150 μg/m3 and 10 mg/m3）,whereas they were found above the permissible limits set by the WHO（40 μg/m3,20 μg/m3 and 10 mg/m3）.In comparison of ANNs model and field observation results in Faisalabad of those pollutants NO2,SO2,CO,PM10 and PM2.5 were higher than the Dalian. |
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