Lockdowns imposed to stop the spread of Covid resulted in “almost no change” in global average particle pollution levels during 2020, and pollution increased in some of the most populous countries, according to a study.
Analysis of revised satellite-derived data on PM2.5 levels, which measures small and dangerous airborne particles, indicates that the economic shutdown imposed across many parts of the world brought clear skies to some areas only temporarily.
According to research by the Air Quality Index for Life, based at the University of Chicago, the weighted average level of PM2.5 for the world’s population fell from just 27.7 to 27.5 g/m3 between 2019 and 2020, remaining more than five times the World Health Organization’s guidance. , which was revised last year to 5 g/m3.
Pollution levels have increased across South Asia – the world’s most polluted region, where residents are expected to lose about five years of their life expectancy if conditions do not improve.
Increases have also been recorded in parts of Southeast Asia, where pollution levels have risen by as much as 25% in some areas.
Brief “blue sky” periods during lockdowns gave a glimpse of what the air could look like, AQLI director Christa Hsinkoff said, but added: “Their relatively minor effects on the long-term quality of the air we breathe underscore that pollution is an intractable problem.”
Some countries recorded a significant drop in pollution in 2020, including Indonesia where year-on-year levels of particulate pollution fell by more than 20% due to a reduction in fire-related haze. Pollution has also decreased significantly in Russia, China, Germany and Japan in 2020 compared to 2019.
Differences were also observed within countries: “While year-on-year average levels of particulate pollution in India increased by 2.9%, Delhi experienced a decrease of nearly 6% in particulate pollution from 2019 to 2020,” Hasenkopf said.
Other densely populated countries where pollution levels worsened included Bangladesh, Nigeria, Pakistan and the United States.
The report said a revision of WHO guidance on the level of particulate pollution that people can breathe means that 97.3% of the world’s population now lives in areas where PM2.5 levels are unsafe.
According to an AQLI analysis, permanently reducing global air pollution to meet WHO guidelines of 5 g/m3 would add 2.2 years to life expectancy, from approximately 72 to 74.2 years.
Hassenkopf said the research did not look at what caused some areas to see ups and downs in pollution, but did point out the possible causes: “We know that in some places, economies were playing a catch-up role after lockdowns, and in others, it was 2020 Like a bad year because of the wildfires.”
The haze caused by thousands of fires on the Indonesian island of Sumatra and Borneo had a significant impact on air quality in 2019. In 2020, pollution in Singapore and Indonesia decreased by 38.3% and 20.3%, respectively.
Elsewhere in Southeast Asia, PM2.5 increased, including in Cambodia (25.9%) and Thailand (10.8%), where researchers cited biomass, wildfires and peatlands, lax fuel emissions standards, and coal-fired power plants. . as major drivers of pollution.