On Wednesday, September 6, there was not a cloud on the horizon and yet the skies over Paris turned gray. The Ile-de-France region experienced a period of ozone pollution due to the lingering effects of the late heat wave in France. Not to be confused with stratospheric ozone, which is the ozone layer that protects us from ultraviolet rays, tropospheric or ground-level ozone is the "bad" ozone and is typically associated with summertime pollution. The combined effect of heat and solar radiation causes the formation of complex chemical reactions, notably between nitrogen oxides (NOx), emitted mainly by road transport and incinerators, and the volatile organic compounds of industrial and household products.
It is one of the already noticeable effects of global warming: Ozone pollution is no longer a phenomenon confined to southern cities nor to the summer months. Ozone peaks are now occurring as early as April and May and are lasting into September. Unlike other pollutants, such as fine particulate matter, nitrogen dioxide and sulfur dioxide – whose average concentrations have been falling since the beginning of the century – ozone concentrations, which have remained unchanged since 2016, are rising again.
In Paris, they have leaped by 25% over the last decade. The trend of rising temperatures and more frequent heat waves is set to worsen globally.
According to a report published Wednesday, September 6, by the World Meteorological Organization (WMO) the escalating intensity and frequency of heatwaves are exacerbating the health risks associated with ozone pollution. Furthermore, the danger doesn't only lie in rising temperatures, but also in the effects of the resulting pollution. The organization is concerned that the deterioration in air quality associated with global warming is often "neglected" by public authorities.
"Heatwaves worsen air quality, with knock-on effects on human health, ecosystems, agriculture and indeed our daily lives," said WMO Secretary-General Prof. Petteri Taalas. "Climate change and air quality cannot be treated separately. They go hand-in-hand and must be tackled together to break this vicious cycle," he said.
In addition to ozone peaks, the WMO has observed other pollution phenomena linked to hot weather such as Saharan sand dust falling on Europe – which was the cause of a health alert in the Pyrenees on Monday, September 4 – and especially, the intensification of wildfires. This year, the megafires that have already burned more than 16 million hectares in Canada, have generated huge clouds of smoke laden with fine particulate matter and have made the air unbreathable as far as New York City. Fine particulate matter presents the most danger to health, as they penetrate deep into the respiratory tract. According to the World Health Organization, lung cancer and strokes caused by exposure to fine particulate matter are responsible for over 4 million premature deaths worldwide every year.
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