Evidence
The impact extends beyond the lungs
Of the estimated 4.2 million premature deaths attributed to outdoor air pollution:
In its 2024 fact sheet, WHO describes ambient air pollution as a major environmental health problem. Fine-particle exposure is linked to respiratory and cardiovascular disease. Its estimate of 4.2 million premature deaths is a worldwide estimate for 2019; it is not a count for a country, city or individual person.
Why it can be invisible
WHO identifies particulate matter as a common air-pollution indicator, alongside pollutants including ozone, nitrogen dioxide and sulfur dioxide. The look or smell of the air is not a measurement, so local data need a location, timestamp and pollutant label.
Risk remains below a limit
WHO does not identify a completely harmless threshold for particulate matter. A reading below a limit does not mean that breathing that air every day for years is harmless. Concentration and exposure duration matter; one current reading does not describe exposure over a whole year.
Action
A local advisory can help people adjust the time or intensity of an outdoor activity. WHO also points to action in transport, energy, industry, waste management and urban planning as necessary to reduce pollution at its sources.
Sources
Educational information; personal health questions belong with your clinician.
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