A new study on global daily levels of air pollution shows that practically every location on Earth has very poor quality air. The study shows that only 0.001% of the human population and 0.18% of the planet’s land surface are below the safety levels recommended by the World Health Organization (WHO). About 99.82% of the world’s land surface is exposed to levels of particulate matter 2.5 (PM2.5), which are particles that scientists have linked to lung cancer and heart disease.
This is explained in a study led by Yuming Guo, from the School of Public Health and Preventive Medicine at Monash University (Australia), and published this month in the review ‘Lancet Planetary Health’. The researchers used traditional air quality monitoring observations, satellite-based meteorological and air pollution detectors, and statistical and machine learning methods to more accurately assess PM 2.5 concentrations on the planet.
“I hope our study can change the minds of scientists and policymakers for the daily PM2.5 exposure,” said Yuming Guo. “Short-term exposure, particularly sudden increase, to PM2.5 has significant health problems. If we can make every day with clean air, of course the long-term exposure of air pollution would be improved.”
According to Forbes magazine, IQAir released last year a study showing that not a single country in the world met the current WHO guidelines on air quality. The report listed Bangladesh, Chad, Pakistan, Tajikistan and India top five most polluted countries in 2021.
The WHO launched new global air quality guidelines in September 2021 that tighten the recommended levels of pollutants in order to prevent millions of deaths due to air pollution, as it considers it to be one of the greatest environmental threats to human health along with climate change. The recommended level of PM2.5 is 5 micrograms per cubic meter in the annual concentration and 15 in the daily concentration, below which are considered safe thresholds for health.
I hope our study can change the minds of scientists and policymakers for the daily PM2.5 exposure.
Yuming Guo, School of Public Health at Monash University
The new study indicates that the annual concentration and days of high PM2.5 exposure in Europe and North America decreased between 2000 and 2019, while they rose in South Asia, Australia and New Zealand, and Latin America and the Caribbean.
More than 70% of days agglutinated fine particulate matter concentrations above safe levels worldwide (more than 90% in South and East Asia). Globally, the annual average PM2.5 between 2000 and 2019 was 32.8 micrograms per cubic meter, with the highest concentrations in East Asia (50.0), South Asia (37.2) and Africa (30.1), and the lowest in Australia and New Zealand (8.5), other regions of Oceania (12.6) and South America (15.6).
According to the reference limit set by WHO in 2021, only 0.18% of the global land area and 0.001% of the global population were exposed to annual exposure below this annual safety threshold in 2019.
Unsafe PM2.5 concentrations show different seasonal patterns in northeast China and northern India during the winter months, while eastern North America has elevated levels of fine particulate matter in summer, as well as in August and September in South America and from June to September in sub-Saharan Africa.
