Air pollution is one of the most pressing environmental issues of our time, with particulate matter (PM2.5) being the leading environmental health risk factor. A recent study by Monash University researchers, published in the prestigious journal Lancet Planetary Health, has shed new light on the state of PM2.5 concentrations across the globe, revealing that only a small percentage of the world’s population is exposed to safe levels of this pollutant.

The study used a combination of traditional air quality monitoring observations, satellite-based meteorological and air pollution detectors, statistical and machine learning methods to more accurately assess PM2.5 concentrations globally. The researchers found that only 0.18% of the global land area and 0.001% of the global population were exposed to PM2.5 levels below the safety limit recommended by the World Health Organization (WHO).

Despite reductions in Europe and North America, PM2.5 pollution is on the rise in Southern Asia, Australia, New Zealand, Latin America and the Caribbean. With more than 70% of days globally seeing levels above what is safe, this is a problem that demands attention.
Only a tiny fraction of the global population is breathing air that meets WHO safety guidelines.

Moreover, the study revealed that while daily levels of PM2.5 have reduced in Europe and North America over the past two decades, levels have increased in Southern Asia, Australia, New Zealand, Latin America, and the Caribbean. In fact, more than 70% of days globally in 2019 had PM2.5 concentrations above the WHO’s recommended safe limit of 15 μg/m³.

The study also found that different regions around the world experience different seasonal patterns of PM2.5 concentrations. For example, Northeast China and North India experience high levels of PM2.5 during their winter months (December, January, and February), while eastern areas in northern America have high levels of PM2.5 during their summer months (June, July, and August).

The health impacts of exposure to PM2.5 are significant and include respiratory and cardiovascular diseases, lung cancer, and premature death. The findings of this study highlight the urgent need for policymakers, public health officials, and researchers to develop effective air pollution mitigation strategies that can help reduce exposure to PM2.5 and its associated health risks.

Furthermore, the lack of pollution monitoring stations globally for air pollution underscores the importance of innovative approaches such as machine learning to estimate global surface-level daily PM2.5 concentrations accurately. With this information, policymakers, public health officials, and researchers can make informed decisions that protect human health and improve the quality of life for people around the world.