Abstract:
Since Pakistan is devoid of a ground-based air quality network, monitoring urban air quality by using satellite data can facilitate with updated information about air quality, thus having vast implications for national policy decisions. AOD from MODIS-Terra was used to study the aerosol trend over Lahore (31.5546° N, 74.3572° E) and Multan (30.1984° N, 71.4687° E) districts from the year 2013 to 2017. In addition, continuous 12-hour sampling of Particulate Matter (PM) (10 and 2.5 microns) was carried out for three months from January to March 2017 in the highly polluted urban cities of Lahore and Multan. In order to test the statistical significance of trend in AOD, the Mann-Kendall seasonal trend analysis was performed. Mass concentrations of PM, and AOD AERONET, located in Lahore, were used to validate AOD observations from MODIS – Terra and Aqua, and determining an empirical relationship, which was further improved by introducing weather parameters. The resultant short-term morbidity in the form of hospital admissions attributable to PM2.5 was estimated by using population health data, the concentration response coefficients recommended by the WHO, the actual measured exposure, and baseline exposures (or counter-factual) for the months of January, February, and March 2017. During the last five years (2013 – 2017), a significant positive trend of AOD was found over Lahore, while the trend over Multan was not significant. PM concentrations were found to be much higher than those recommended by WHO and Pak-NEQS, and a positive association was found between PM and MODIS AOD. Also, MODIS AOD when compared with AERONET AOD revealed a significant correlation (R) of 0.76 and 0.89 with Terra and Aqua respectively. Moreover, hospital admissions (respiratory diseases) attributable to PM2.5 were also found to be substantial during the selected time period.
