WMO Air Quality and Climate Bulletin No. 5 – September 2025
- Air quality and climate change are closely interlinked
- Integrated action is win-win for health, economies and ecosystems
- Bulletin addresses wildfires, winter fog, shipping emissions and urban pollution
- Tiny particles called aerosols have major impact
- Cross-border hazards demand international coordination
- Improved monitoring is vital for risk management and forecasts
The WMO Air Quality and Climate Bulletin No. 5 – September 2025 report traces the complex interplay between air quality and climate, stressing that both must be addressed together to protect human health, ecosystems, and economies. The report highlights wildfires, winter fog, shipping emissions and urban pollution, with an emphasis on the role of aerosols.
It stresses the need for improved atmospheric monitoring and more integrated policies to safeguard human and environmental health and reduce agricultural and economic losses.
While regulatory action has reduced aerosol concentrations in parts of North America, Europe, and East Asia, levels remain high or are increasing in South Asia, South America, and high latitudes, largely due to wildfires and industrial activity.
PM2.5 pollution remains a major global health risk, causing millions of premature deaths annually. In 2024, levels declined in eastern China but stayed high in northern India and spiked in Canada, Siberia, central Africa, and the Amazon, where record wildfires spread pollution as far as Brazilian cities.
The Bulletin also reports worsening winter fog in the Indo-Gangetic Plain, now linked more to human activity than seasonal weather. Shipping rules cutting sulphur emissions improved health but slightly accelerated warming by reducing aerosol cooling.
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About the WMO Air Quality and Climate Bulletin series
Ongoing climate change, caused by the accumulation of greenhouse gases in the atmosphere, is happening on a timescale of decades to centuries and is driving environmental changes worldwide. In contrast, the air pollution that occurs near the Earth’s surface happens on a timescale of days to weeks, and across spatial scales that range from local (for example, urban centres) to regional (such as the eastern United States of America, northern India or the Amazon).
Despite these wide‑ranging differences, air quality and climate change are strongly interconnected. The WMO Air Quality and Climate Bulletin reports annually on the state of air quality and its connections to climate change, reflecting on the geographical distribution of and changes in the levels of traditional pollutants.
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