WMO Report: Heat Waves and Wildfires Drive Global Air Pollution in 2025

For Europe, the data paints a nuanced picture: phases of intense heat and active fire sites on the Iberian Peninsula coincided with elevated particulate matter and ozone levels. Similar spikes occurred in North America, particularly during the summer months.

Link Between Heat and Pollutants

WMO scientists emphasize that the measured deviations are not statistical noise but are consistent with previous years. The map of anomalies resembles the maps from previous assessments and underscores the influence of heat and fire.

The report links short-term weather phenomena with longer-term climate changes. More frequent heat waves, according to the report, create more favorable conditions for the photochemical formation of ozone and extend the season in which wildfires can easily ignite and spread.

Spanish authorities had repeatedly reported critical ozone levels in recent summers. The new analyses support these national observations and place them in a global context.

Regional Differences

A look at Amazonia provides a counterpoint: there, concentrations were below the long-term average. The WMO attributes this partly to a less intense fire season in parts of the rainforest region, but points out that individual years do not constitute a trend reversal.

The WMO stresses that the data basis for political decisions must continue to be expanded. Satellite observations, ground-based measurement networks, and model calculations together only yield robust statements when they are systematically combined.

Health Consequences

Health authorities in the affected regions see a need for action. High ozone and particulate matter levels particularly burden people with respiratory or cardiovascular diseases and can cause hospital admissions with sustained exposure.

Looking ahead, the report's authors expect that heat- and fire-related air pollution will continue to increase as global temperatures rise. The WMO simultaneously calls for better early warning and enhanced measurement.