“The connection between Covid-19 and air pollution has shed new light on the latter, especially because many locations have observed visibly cleaner air, revealing that improvements in air quality are possible with collective action. urgent, ”the report states.
Researchers at IQAir, a global air quality information and technology 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 locks on circuit breakers and widespread business closures – recorded the largest reductions in PM 2.5. But that effect will not last: air pollution levels are likely to rise as Covid-19 containment measures are completed and companies are restarted, according to the report.
In general, locations in South Asia and East Asia continue to top the list of the most polluted places in the world, according to the report. Bangladesh, China, India and Pakistan share 49 of the 50 most polluted cities in the world.
Hotan, an oasis city in the Xinjiang region of western China, was ranked as the most polluted city in the world by 2020. Its annual levels of PM 2.5 averaged 110.2 micrograms. per cubic meter, 11 times the World Health Organization’s annual exposure target. At Hotan Peak, these levels rose to 264.4 in March, deep in “dangerous” territory.
Xinjiang has seen rapid increases in coal and fossil fuel emissions, according to the report. Land degradation caused by humans and climate change have also increased the severity of droughts, creating more frequent sandstorms 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, according to the report. The country is making great strides in renewable energy, but these sources account for only 23% of China’s energy consumption, while coal accounts for 58%.
After Hotan, the next 13 most polluted cities are in India, where the main sources of pollution include transportation, construction and waste incineration.
In the northern provinces of Punjab and Haryana, farmers also practice stubble burning: they intentionally set fire to cultivated fields to prepare the land for their next crop. Stubble burning incidents in Punjab reached record levels in 2020, with an increase of 46.5% over 2019. Up to 40% of air pollution in the capital Delhi comes from Punjab agricultural fires, according to the report .
The global decline in human emissions in 2020 was also partially offset by “extreme events of air pollution”, such as forest fires and dust storms, which are linked to the worsening climate crisis and unpredictable climate throughout the world. world.
Forest fires devastated parts of the United States, Australia, South America, Indonesia and more, causing large rises in air pollution and emitting large amounts of greenhouse gases. Sao Paulo, Los Angeles and Melbourne, all affected by heavy forest fires, experienced the largest increase in PM 2.5 levels compared to 2019.
But there are also bright spots. The 25 most polluted cities in South Asia have seen a fall 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 tend to decline. 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.