These first conclusions support the theory that asteroids brought organic matter to Earth for the birth of life on the planet.
A pioneering study of the daily level of fine particulate matter in the environment (PM2.5) around the world found that almost no place on Earth is safe from air pollution.
Only 0.18 percent of the world’s land surface and 0.001 percent of the world’s population are exposed to levels of PM2.5 – the world’s leading environmental health risk factor – below the safety levels recommended by the World Health Organization (WHO).
The research, conducted by Monash University, Australia, and published in The Lancet Planetary Health journal, notes that while daily levels have been falling in Europe and North America in the two decades to 2019, they were rising in southern Asia, Australia, New Zealand, Latin America and the Caribbean, with more than 70 percent of days around the world with levels above what is safe.
The lack of air pollution monitoring stations around the world has resulted in a lack of data on local, national, regional and global exposure to PM2.5. Now this study, led by Professor Yuming Guo, from Monash University’s School of Public Health and Preventive Medicine, provides a map of PM2.5 trends around the world in recent decades.
The research team used traditional air quality monitoring observations, satellite weather and air pollution detectors, and statistical and machine learning methods to more accurately assess PM2.5 concentrations around the world, according to Professor Guo. .
“In this study, we used an innovative machine learning approach to integrate multiple meteorological and geological information to estimate daily surface-level PM2.5 concentrations globally with a high spatial resolution of approximately 10 km x 10 km. for global grid cells in 2000-2019, focusing on areas above 15 micrograms/m3, which is considered by WHO to be the safe limit (threshold remains debatable),” it states in a statement.
The study reveals that the annual concentration of PM2.5 and days of high PM2.5 exposure in Europe and North America decreased over the two decades of the study, while exposures increased in South Asia, Australia and New Zealand, and Latin America and the Caribbean.
In addition, the study found that despite a slight decrease in PM2.5 high exposure days globally, in 2019 more than 70 percent of days still had PM2.5 concentrations greater than 15 micrograms/m3 .
In South and East Asia, more than 90 percent of the days had daily PM2.5 concentrations greater than 15 micrograms/m3.
Australia and New Zealand saw a marked increase in the number of days with high PM2.5 concentrations in 2019. Globally, the annual mean PM2.5 from 2000 to 2019 was 32.8 micrograms/m3.
The highest concentrations of PM2.5 were distributed in the East Asian (50.0 micrograms/m3) and South Asian (37.2 micrograms/m3) regions, followed by North Africa (30.1 micrograms/m3). Australia and New Zealand (8.5 micrograms/m3), other regions of Oceania (12.6 micrograms/m3) and South America (15.6 micrograms/m3) had the lowest annual PM2.5 concentrations.
Based on the new WHO guideline limit for 2021, only 0.18 percent of the global land area and 0.001 percent of the global population were exposed to an annual exposure below this guideline limit (annual mean of 5 micrograms/m3 ) in 2019.