“The link between Covid-19 and air pollution has shed new light on the latter, especially as many places have visibly observed cleaner air. It appears that improving air quality is possible with urgent, collective action,” the report said.
Researchers at IQAir – a global air quality information and technology company – analyzed pollution data from 106 countries and specifically measured PM 2.5, a microscopic pollutant that can pose serious health risks.
Singapore, Beijing and Bangkok – which all imposed power outages and widespread business closures – saw the biggest decline in PM 2.5. But this effect will not last: air pollution levels are likely to rise as Covid-19 controls end and businesses resume, the report said.
In general, the South Asian and East Asian locations still remain at the top of the list of most polluted places in the world, the report reads. Bangladesh, China, India and Pakistan share 49 of the 50 most polluted cities worldwide.
Hotan, an oasis city in the western Xinjiang region of China, was ranked as the world’s most polluted city by 2020. Its annual levels of PM 2.5 averaged 110.2 micrograms per cubic meter – 11 times higher than the World Health Organization’s target for annual exposure. At Hotan’s peak, levels rose to 264.4 in March – deep in ‘dangerous’ territory.
Xinjiang has seen rapid increases in coal and fossil fuel emissions, the report said. Human-caused soil degradation and climate change have also increased the severity of droughts, resulting in more frequent sandstorms and dust storms contributing to extreme pollution.
China is still the largest producer and consumer of coal in the world, making a major contributor to PM 2.5 pollution. The country is making great strides in renewable energy – but these sources make up 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 major sources of pollution include transportation, construction and waste incineration.
In the punjab provinces of Punjab and Haryana in the north of the country, farmers are also practicing stubble burning – deliberately setting fire to lands to prepare the land for the next harvest. Stubborn fire 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, according to the report, comes from Punjab farm fires.
The global decline in human-related emissions in 2020 is also partially offset by ‘extreme air pollution events’ such as wildfires and dust storms, which are linked to the worsening climate crisis and the unpredictable weather worldwide.
Wildfires devastated parts of the United States, Australia, South America, Indonesia and more – causing huge increases in air pollution and releasing large amounts of greenhouse gases. Sao Paulo, Los Angeles and Melbourne – all affected by severe wildfires – saw the biggest rise in PM 2.5 levels compared to 2019.
But there are also bright spots. The 25 most polluted cities in South Asia saw a drop in PM 2.5. since 2019, or has shown an overall 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 are generally declining. In South Korea, all cities improved their air quality in 2020, after new measures were introduced to control the seasonal impact of coal on air pollution.