Air quality: what a study of fine particles found across 136 countries
The Cambridge model estimates that meeting the WHO guideline for PM₂.₅ could prevent or postpone about 9.4 million deaths in one year.
How might mortality change if 136 low- and middle-income countries met World Health Organization (WHO) air quality guidelines? A University of Cambridge study published on 10 November in Environment International estimates that meeting the guideline for fine particulate matter (PM₂.₅) could prevent or postpone about 9.4 million deaths in one year across the countries studied.
For nitrogen dioxide (NO₂), the corresponding scenario estimates about 1.1 million deaths prevented or postponed. The two estimates cannot be added together because the exposed populations and effects of the pollutants may overlap.
What the model measures
The researchers combined pollution, population and health data with published evidence linking exposure to disease and mortality. They compared scenarios with different pollutant concentrations. The results estimate what could happen under those conditions; they are neither a count of deaths already prevented nor a forecast for any individual country.
The model also examined the WHO’s less stringent interim targets. For PM₂.₅, that scenario yielded an estimate of around 6.6 million fewer deaths. The comparison shows why a gradual reduction in exposure can matter even where the final guideline cannot be reached immediately.
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