“The connection between Covid-19 and air pollution has shed new light on the latter, especially as many sites have seen visibly cleaner air – revealing that improvements in air quality are possible with urgent collective action,” the report said. .
Researchers at IQAir – a global air quality technology and information company – analyzed pollution data from 106 countries, specifically measuring PM 2.5, a microscopic pollutant that can cause serious health risks.
Singapore, Beijing and Bangkok – all of which imposed circuit breaker blocks and generalized business closings – saw the biggest reductions in PM 2.5. But that effect will not last: air pollution levels are likely to increase as Covid-19’s containment measures end and business resumes, the report said.
Overall, localities in South and East Asia remain at the top of the list of the most polluted places in the world, the report concluded. Bangladesh, China, India and Pakistan share 49 of the 50 most polluted cities in the world.
Hotan, an oasis city in China’s western Xinjiang region, was ranked as the most polluted city in the world in 2020. Its annual PM 2.5 levels averaged 110.2 micrograms per cubic meter – 11 times higher than the World Health Organization target for annual exposure. At the peak of Hotan, these levels reached 264.4 in March – deep within “dangerous” territory.
Xinjiang has seen rapid increases in emissions from coal and fossil fuels, the report said. Man-made land degradation and climate change have also increased the severity of droughts, which create more frequent sand and dust storms that contribute to extreme pollution.
China also remains the world’s largest producer and consumer of coal, a major contributor to PM 2.5 pollution, the report said. The country is making great strides in renewable energy – but these sources represent only 23% of China’s energy consumption, while coal accounts for 58%.
After Hotan, the next 13 most polluted cities are all in India, where the main sources of pollution include transportation, construction and burning of waste.
In the northern provinces of Punjab and Haryana, farmers also practice burning stubble – intentionally setting fire to cultivated fields to prepare the land for their next harvest. Stubble-burning incidents in Punjab reached record levels in 2020, with an increase of 46.5% compared to 2019. Up to 40% of air pollution in the capital Delhi originates from fires in Punjab farms, according to the report.
The global reduction in human-related emissions in 2020 was also partially offset by “extreme air pollution events”, such as forest fires and dust storms, which are linked to the worsening climate crisis and unpredictable climate around the world.
Forest fires have devastated parts of the United States, Australia, South America, Indonesia and more – causing huge spikes in air pollution and emitting huge amounts of greenhouse gases. São Paulo, Los Angeles and Melbourne – all affected by serious forest fires – saw the biggest increase in PM 2.5 levels compared to 2019.
But there are also positive points. The 25 most polluted cities in South Asia recorded a drop in PM 2.5. since 2019, or showed a general downward trend over the past four years. East Asian countries have also made efforts to improve air quality, and PM 2.5 levels in the region generally show a downward trend. In South Korea, all cities saw their air quality improve in 2020, after new measures were enacted to control the seasonal impact of coal on air pollution.