New WHO Global Air Quality Guidelines (AQGs) have lowered the acceptable limits of air pollution, providing evidence that even lower concentrations than previously understood have a negative health impact.
Increasing evidence showing how air pollution affects different aspects of health, WHO has adjusted almost all the AQGs levels downwards, warning that exceeding the new air quality guideline levels is associated with significant risks to health.
Air pollution is estimated to cause 7 million premature deaths and the loss of millions more healthy years of life. In children, this could include reduced lung growth and function, respiratory infections and aggravated asthma. In adults, deaths from ischaemic heart disease and stroke are the most common, as well as emerging evidence of diabetes and neurodegenerative conditions. This makes the disease burden from air pollution on par with others such as unhealthy diet and tobacco smoking.
Besides climate change, air pollution is one of the biggest environmental threats to human health. Improving air quality will also help mitigate climate change, thereby reducing the negative health impacts of both.
WHO’s new guidelines recommend air quality levels for 6 pollutants, where evidence has advanced the most on health effects from exposure. When action is taken on these so-called classical pollutants – particulate matter (PM), ozone (O₃), nitrogen dioxide (NO₂) sulfur dioxide (SO₂) and carbon monoxide (CO), it also has an impact on other damaging pollutants.
Particulate matter equal or smaller than 10 and 2.5 microns (µm) in diameter (PM₁₀ and PM₂.₅, respectively) is a particular health concern. Both PM₂.₅ and PM₁₀ can penetrate deep into the lungs but PM₂.₅ can even enter the bloodstream, primarily resulting in cardiovascular and respiratory impacts, and also affecting other organs, and were classified as carcinogenic in 2013.
“Air pollution is a threat to health in all countries, but it hits people in low- and middle-income countries the hardest,” said WHO Director-General, Dr Tedros Adhanom Ghebreyesus. “WHO’s new Air Quality Guidelines are an evidence-based and practical tool for improving the quality of the air on which all life depends. I urge all countries and all those fighting to protect our environment to put them to use to reduce suffering and save lives.”
In 2019, over 90% of the world’s population lived in areas where concentrations exceeded the 2005 WHO air quality guideline for long term exposure to PM₂.₅.
Almost 80% of PM₂.₅-related deaths could be avoided if current air pollution levels were reduced to those proposed in the updated guideline. At the same time, reaching interim targets would reduce the burden of disease, of which the greatest benefit would be observed in countries with high concentrations of fine particulates (PM₂.₅) and large populations.
Source: World Health Organization
