An Emerged Challenge of Air Pollution and Ever-Increasing Particulate Matter in Pakistan; A Critical Review.

This study, for the first time, aims to evaluate the situation of air quality in Pakistan critically; through a detailed assessment of sources, policies, and key challenges to identify the plausible way forward. Air pollution and particulate matter have merged as a global challenge in recent years because of its growing health and socio-economic risks. The intensity and impacts of these risks have become more pronounced, especially in developing countries like Pakistan that lack adequate warning, protection, and management systems. Various epidemiological studies have linked poor air quality with different health disorders and increasing death rates. In Pakistan, mortality rates as a result of exposure to increased levels of air pollutants, especially particulate matter, are alarming. According to the World Bank's estimates, Pakistan's annual burden of disease from outdoor air pollution is responsible for around 22,000 premature adult deaths and 163,432 DALYs (disability-adjusted life years) lost. The concentration of major air pollutants in Pakistan, such as NOx, O3, and SO2 have also been increasing significantly over the last two decades. Several studies are also reporting multiple instances of air quality around the major cities of Pakistan being consistently exceeding the national guidelines. During teh year 2019 PM2.5 cocnentrations in the city of Lahore revealed that almost every single day was in exceedance of the WHO and national air quality standards. Although the substantial effects of these rising pollutant concentrations in Pakistan have been stated in a few studies, however, the total extent, nature of contributing factors, and consequences remain inadequately understood. This study aims to use data available from monitoring stations, satellites, and literature to highlight the gaps in our understanding and emphasize the critical challenges associated with poor air quality faced in Pakistan. Topmost is the lack of air quality monitoring systems followed by poor initiatives by policymakers and enforcement agencies. A way forward while addressing these key challenges is also discussed, which focuses on the development of flexible monitoring, new technologies, and monitoring approaches in addition to communications among the various public, private agencies, and all relevant stakeholders.

Investigating the impact of Glyoxal retrieval from MAX-DOAS observations during haze and non-haze conditions in Beijing.

This study presents the Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements for Glyoxal (CHOCHO) in Beijing, China (39.95°N, 116.32°E). CHOCHO is the smallest compound of di-carbonyl group. As a primary sink of CHOCHO, its photolysis with NOx (oxides of nitrogen) results in the production of tropospheric ozone. Therefore, the focus of CHOCHO DOAS measurements is increasing in trend. We did the measurements from 09 May 2017 to 09 September 2017. The study was conducted to compare different retrieval settings in order to reveal best DOAS fit settings for CHOCHO; furthermore, effect of haze and non-haze days on CHOCHO concentration was examined. The root mean square of residual and Differential Slant Column density (dSCD) error was reduced when measurements were done with lower wavelength limit around 432-438 nm and upper intervals around 455-460 nm. Thus, lower wavelength intervals around 432-438 nm and upper intervals around 457-460 nm were best for the retrieval of dSCDs for CHOCHO. Meteorological conditions like haze or non-haze days did not have significant effect on DOAS fit parameters. The CHOCHO vertical column densities range from 1.33E+14 to 9.77E+14 molecules/cm2 during the study period with average of 6.16E+14 molecules/cm2. The results indicated that during haze days CHOCHO concentration was higher because of lower rate of photolysis and atmospheric oxidation potential. Our results did not show any significant weekend effect on CHOCHO atmospheric concentration.