air pollution PM2.5

Over 99 per cent of humans exposed to unsafe levels of PM2.5 air pollution

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Over 99 per cent of the global human population is exposed to ambient fine particulate matter (PM2.5) that exceeds safe levels for healthy breathing, a study has found.

A study at Monash University in Australia  found that only 0.18 per cent of the global land area and 0.001 per cent of the global population are exposed to levels of PM2.5 below that recommended by the Word Health Organization (WHO).

Particles in the PM2.5 size range are able to travel deeply into the respiratory tract, reaching the lungs. Exposure to fine particles can cause short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath.

Studies also suggest that long term exposure to fine particulate matter may be associated with increased rates of chronic bronchitis, reduced lung function and increased mortality from lung cancer and heart disease.

While daily levels have reduced in Europe and North America in the two decades to 2019, levels have increased Southern Asia, Australia, New Zealand, Latin America and the Caribbean, with more than 70 per cent of days globally seeing levels above what is safe.

A lack of pollution monitoring stations globally for air pollution, has meant a lack of data on local, national, regional and global PM2.5 exposure, the researchers said.

The team utilised 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.

“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,” said study leader professor Yuming Guo.

In southern Asia and eastern Asia, more than 90 per cent of days had daily PM2.5 concentrations higher than recommended levels.

Australia and New Zealand had a marked increase in the number of days with high PM2.5 concentrations in 2019.

According to Professor Guo, the unsafe PM2.5 concentrations also show different seasonal patterns “included North-east China and North India during their winter months (December, January, and February), whereas eastern areas in northern America had high PM2.5 in its summer months (June, July, and August),” he said.

“We also recorded relatively high PM2.5 air pollution in August and September in South America and from June to September in sub-Saharan Africa.”

He added that the study is important because “It provides a deep understanding of the current state of outdoor air pollution and its impacts on human health. With this information, policymakers, public health officials, and researchers can better assess the short-term and long-term health effects of air pollution and develop air pollution mitigation strategies.”

The UK government has been urged to amend the Environment Bill to include targets for lower concentrations of air pollutant PM2.5 particles.

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