Table 2.
Analysis of current air quality work during COVID-19 across different regions of the world.
| Issues addressed/Major outcomes | Region | Reference |
|---|---|---|
| Restricted human activities have contributed to air quality deterioration and reduced excessive associated risk. | Major cities of India | Sharma et al. (2020) |
| Deficient air quality regions are related to high mortality rates. | China | Isaifan (2020) |
| In several cities, lockout led to an increase in the quality of air and a decrease in premature death. | China | (Wang and Su, 2020), (He et al., 2020) |
| The air pollution and Covid-19 infection relationship is considerable. | China | Xie et al. (2020) |
| Decrease of primary pollutants (like NOx) during lockdown offers compensation for increased secondary pollutants (like O3). | China | Huang et al. (2020) |
| Adverse weather conditions overwhelmed emissions reductions. | China | Wang et al. (2020b) |
| Significant decrease in most contaminants and increased concentrations of ozone during the lockdown. | Spain | Tobías et al. (2020) |
| Accelerated Covid-19 transmissions are mainly using “air pollution -to -human transmission” rather than “human -to -human transmission”. | Italy | Coccia (2020) |
| Mean temperature, minimum temperature and air quality were strongly related to Covid-19 outbreak. | New York, USA | Bashir et al. (2020) |
| After four days of lockdown in Delhi, about 40–50% enhancement in the quality of air is identified. | Delhi, India | Mahato et al. (2020) |
| The Covid-19 pandemic lock-down caused the quality of air in many cities around the world to increase and water pollution to decrease in some parts of the world. | Major cities of the world | Saadat et al. (2020) |
| The AQI and concentrations of PM2.5 were decreased by 25% within weeks. | China | (Guojun et al., 2020), (He et al., 2020) |
| Reducing concentrations of PM2.5 and NO2 in China, Germany, Spain, France and Italy. | Major cities of the world | Zambrano-Monserrate et al. (2020) |
| A sudden drop in CO2 emission profile in the atmosphere. Decreased percentage of CO2 ranged from 24.56 to 45.37 at Deshbandhu park and Sealdah station respectively. | Kolkata, India | Mitra et al. (2020) |
| Reduction in the concentration of major air contaminants PM2.5, PM10, NO2 and CO in most cities around the world. | Major cities of the world | Shrestha et al. (2020) |
| A decrease in concentrations of major air pollutants. | Cities across the globe | Muhammad et al. (2020) |
| Observable air pollution reduction following lockdown. | Cities across the globe | Anjum (2020) |