Early heatwave: accelerated climate change and its impact on air quality

This pollution episode perfectly illustrates that climate change is not limited to a rise in temperatures: it also contributes to the degradation of air quality and increases the health risks associated with air pollution.

Climate and air quality: an increasingly visible link

Ozone pollution episodes occur mainly during hot and sunny periods. Ozone is a so-called "secondary" pollutant: it is not found directly in the air but is formed under the effect of solar radiation from precursor pollutants, notably nitrogen oxides and volatile organic compounds from road traffic, industrial activities or certain agricultural activities.

The early occurrence of these episodes*, facilitated by the high temperatures observed from the end of May, directly illustrates the link between climate change and air quality.

With global warming, heat waves are becoming earlier, more frequent, and more intense. These weather conditions promote ozone formation and exacerbate episodes of air pollution.

Climate change is exacerbating air pollution and complicating the sustainable improvement of air quality. Recent work by the National Air Council (CNA) highlights, in particular, that rising temperatures promote ozone episodes, making it more difficult to achieve air quality targets.

Climate and air quality: an increasingly visible link

Ozone is a pollutant that can have significant consequences for both human health and agriculture.

In humans, it irritates the respiratory tract and can cause breathing difficulties, worsen asthma or certain chronic illnesses, particularly in the most vulnerable individuals: children, the elderly, pregnant women, or people suffering from respiratory and cardiovascular diseases. The health effects of ozone are now well-established. During the 2003 heatwave, several scientific studies showed that high ozone concentrations contributed to the excess mortality observed during that event.

Ozone also affects plants. By disrupting photosynthesis, it weakens crops and can lead to yield losses of 3 to 20%, depending on the agricultural product. Research conducted by INRAE ​​in the Île-de-France region has shown that an increase in ozone concentrations during wheat growth can lead to yield losses of up to 20%. At the French and European levels, several studies have also highlighted major economic consequences for the agricultural sector. The APollO study published by ADEME in 2020 estimated annual losses related to ozone at nearly one billion euros for common wheat and over one billion euros for grasslands.

These impacts serve as a reminder that air pollution is also a public health, agricultural economy and food security issue.

Monitor air quality and adopt the right habits

The Approved Air Quality Monitoring Associations (AASQA) ensure continuous monitoring of air quality and publish their forecasts and recommendations daily.

In the event of a pollution episode, it is recommended to:

• Limit intense outdoor physical activity;
• Prioritize travel that produces the fewest emissions;
• Avoid the use of solvents or products that emit high levels of emissions;
• Follow the health recommendations issued locally.

Check the AASQA websites to follow the forecasts for the coming days

*In Île-de-France, you have to go back to April 15, 2007 to find an episode of ozone pollution before June and to 2011 in Auvergne-Rhône-Alpes.