A study from the Danish Cancer Institute has revealed that people who breathe polluted air have a higher chance of developing meningioma, a tumor that is rarely cancerous but can harm brain tissue, nerves, or blood vessels.
The study was carried out over a 21-year span on four million Danish adults and was published on July 9 in Neurology, the journal of the American Academy of Neurology.
While breathing polluted air is often considered a concern mainly for those in densely populated urban areas, it’s a global issue. According to the World Health Organization (WHO), nearly 99% of the world’s population breathes air that is considered unclean.
The Danish Cancer Institute study adds to the growing body of evidence linking air pollution to serious health consequences. Indeed, air pollution causes seven million premature deaths each year and previous research has suggested that ultrafine particles may damage brain tissue.
The concentration of PM2.5 (measured in micrograms per cubic meter, or µg/m3), which refers to inhalable particles no larger than 2.5 micrometers, poses the greatest risk to human health. PM2.5 is frequently used as a standard for legal air quality limits and the WHO suggests an annual threshold of 5µg/m3 as the indicator of clean air.
However, many parts of the world are recording dangerous levels of air pollution, in some cases 15 times above safe levels. The Air Quality Index (AQI) project, based on average PM2.5 levels, released its 2024 list of the 25 cities with the most severe air pollution in the world. As a general guide, air quality with a PM2.5 (μg/m3) of between 0-12.0 is considered good; 12.1-35.4 is moderate; 35.5-55.5 is unhealthy for sensitive groups; 55.6-150.4 is unhealthy; PM2.5 150.5-250.4 is very unhealthy; and 250.5 or greater is hazardous.
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