The world’s 50 most polluted cities are located in Asia. This issue is of great concern as air pollution continues to be one of the biggest health threats to humanity, killing more than one million people annually of whom 600,000 are children according to the 2020 World Air Quality Report. Around 91% of the global population lives in areas with air quality that exceeds the limits defined as safe by the World Health Organization.
The emissions from fossil fuels alone cause air pollution that costs the global economy US$2.9 trillion annually, accounting for 3.3% of global GDP. While the coronavirus pandemic decreased the level of pollutants in the atmosphere by forcing cities into lockdown, the air quality levels remain alarmingly high in developing countries.
Polluted air major danger to health
Air quality, being vastly impacted by human activities, is closely linked to climate change since many drivers of air pollution also release CO2 emissions and other pollutants that impact the climate.
Each year, 4.2 million people die globally because of ambient (outdoor) air pollution, and 3.8 million pass away as a result of household air pollution derived from unclean cooking stoves and fuels. Air pollution causes heart disease, lung cancer, and severe and chronic respiratory illnesses. The main sources of outdoor contamination are domestic energy for cooking and heating, cars, power stations, agriculture, waste to energy plants, and industry. In the case of indoor pollution, burning fuels such as dung, wood, and coal in ineffective facilities emit different pollutants that are dangerous for health including particulate matter. Furthermore, households that depend on fuel-burning devices suffer a higher risk of burns, poisoning, musculoskeletal injuries, and accidents.
Global ranking
According to the IQAir ranking based on aggregated PM2.5 data from 106 countries, most polluted cities are located in South and East Asia. Bangladesh, China, India, and Pakistan are home to 49 of the 50 most polluted cities in the world ranking. China’s Hotan tops the ranking followed by nine of the most contaminated cities worldwide that are located in India.
Fig.1. Top 10 polluted cities
The fact that India and China lead the ranking is no surprise as both countries have experienced intensive and rapid industrial development meaning that pollution is unavoidable. While both countries have recently implemented policies to improve this situation, several cities still remain dangerous to live in. Overall, 22 of the 30 most contaminated cities worldwide are located in India.
Impact of the pandemic on the air pollution level
The Coronavirus pandemic has had an enormous impact on air quality as it forced lockdowns in many cities around the world. As a result, the fossil fuel consumption level dropped causing a temporary but nevertheless significant decline in the level of pollutants in the air. Overall, 65% of cities worldwide recorded air quality improvements in 2020 compared to the previous year. However, 2020 also introduced several life-threatening air pollutants such as wildfires and dust storms across different countries. Wildfires caused major air pollution spikes in the United States, Australia, Siberia, and South America which released copious amounts of greenhouse gases into the atmosphere.
