Groundbreaking air pollution study finds almost no safe place on Earth

Only 0.001 percent of the global population is exposed to WHO-safe levels.
Sade Agard
Aerial view air pollution concept
Aerial view air pollution concept


Just 0.001 percent of the world's population, according to a groundbreaking study published in Lancet Planetary Health on March 6, of daily ambient fine particulate matter (PM2.5) globally, is exposed to safe levels advised by the World Health Organization (WHO).

The lack of air pollution monitoring stations has led to an absence of information on local, national, regional, and global PM2.5 exposure. Now, this new analysis, which also produced a map, is the first in the world to demonstrate how the global distribution of PM2.5 has changed over the past few decades.

Significantly, the study offers a thorough grasp of the situation of outdoor air pollution today and how it affects people's health. Better yet, its data could help inform policymakers, public health sector representatives, and researchers more accurately determine the short- and long-term health effects of air pollution and create mitigation plans.

The world's worst air pollution hotspots

"In this study, we used an innovative machine learning approach to integrate multiple meteorological and geological information to estimate the global surface-level daily PM2.5 concentrations at a high spatial resolution of approximately ten km (kilometers) × ten km," explained lead author Professor Yuming Guo in a press release.

From this approach, his team at Monash University School of Public Health and Preventive Medicine in Australia developed global grid cells from 2000-2019. These focused on areas above 15 μg/m³ (micrograms per cubic meter air), which is considered the safe limit by WHO.

Based on the 2021 WHO guideline limit, only 0.18 percent of the global land area was exposed to an annual exposure lower than this limit in 2019.

They discovered that in the two decades leading up to 2019, daily levels in Europe and North America have decreased. 

However, levels have risen for Southern Asia, Australia, New Zealand, Central America, and the Caribbean, collectively recording more than 70 percent of days above what is safe.

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In addition, the study found that more than 90 percent of days in southern and eastern Asia had daily PM2.5 concentrations higher than 15 μg/m³.

From 2000 to 2019, the annual average PM2.5 level worldwide was 32.8 µg/m3. The highest PM2.5 concentrations were distributed in the regions of Eastern Asia (50.0 µg/m3) and Southern Asia (37.2 µg/m3), followed by northern Africa (30.1 µg/m3).

Australia and New Zealand (8.5 μg/m³), other regions in Oceania (12.6 μg/m³), and southern America (15.6 μg/m³) had the lowest annual PM2.5 concentrations.

According to Professor Guo, the unsafe PM2.5 concentrations also show different seasonal patterns. For instance, the team recorded relatively high PM2.5 air pollution in August and September in South America and from June to September in sub-Saharan Africa.

The full study was published in Lancet Planetary Health on March 6 and can be found here.

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