First close insight into global daily gapless 1-km PM2.5 pollution, variability, and health impact

Today, Nature Communications published a study entitled "First close insight into global daily gapless 1-km PM2.5 pollution, variability, and health impact" by Jing Wei (Assistant Research Scientist) and Zhanqing Li (Distinguished University Professor) of the University of Maryland, USA and collaborators from the US and foreign institutes. Using an advanced machine-learning model and big data, the team obtained the world's first daily 1-km seamless PM2.5 (particulate matter with diameters less than 2.5 μm) product for the period 2007 to the present. This product presents detailed spatiotemporal distributions of air pollutants around the world, revealing dramatic changes associated with anthropogenic and natural events such as worldwide pandemic episodes. Around the world, 96%, 82%, and 53% of human-inhabited areas were exposed to unhealthy air for at least one day, one week, and one month in a year, respectively. The top-twenty most polluted countries are located in North Africa, the Middle East (65%), and South and East Asia (25%), among which Kuwait, Pakistan, India, and China topped the list. However, a drastic improvement in pollution levels has occurred in China, with a 30% reduction in the last few years. The exposure risk has strong contrasts between developed and developing countries, urban and rural areas, and within cities (even at the neighborhood level). The risk of death associated with air pollution is also high. Natural disasters such as biomass burning also have strong impacts on regional air quality. PM2.5 pollution has become an increasing threat around the world, being the #1 cause of bad air quality in some developed countries like the US and Australia, especially during strong El Niño years like 2020, with PM2.5 levels jumping to 224% of the normal level in the US, killing more people than those killed by fires.

The global product and findings presented are valuable for air quality monitoring, climate change, and public health studies, providing crucial scientific evidence for future air pollution prevention and control, especially at small to medium scales and in urban areas. It allows for a detailed assessment of the spatial non-uniformity and variations in pollution within major cities and the evaluation of associated health risks, providing a scientific foundation for environmental justice.

Global distribution of daily 1-km gapless PM2.5 on 8 October 2020 (unit: μg m-3) at a 1-km spatial resolution and zoomed-in maps showing ground-based measurements (colored dots) over the (a) western United States, (b) central South America, (c) eastern United States, (d) Europe, (e) northwestern Africa, (f) Australia, (g) India, and (h) eastern China.