Some 95 percent of sports venues in the Paris region exceed the World Health Organisation's air quality recommendations, according to a French watchdog.
Almost all the sports grounds in the greater Paris region are overexposed to air pollution, according to Respire ("Breathe"), which looked into into air quality at sites around the French capital.
Its results, released this week, showed that "almost all" of the worst polluted sites were close to the Paris ring road.
The "vast majority" of 112 sports centres studied in Paris and its suburbs have air pollution above the maximum levels recommended by the WHO, according to the study, which used data from French air monitoring service Airparif.
"Spikes in pollution can prevent sports people from reaching elite performance levels and cause asthma attacks and even dizzy spells," the report said, especially during the summer months where pollution levels are at their highest.
Pollution hotspots
The open-air sports ground at Porte d'Asnières between Paris and Levallois-Perret was the most polluted in 2023. The ring road is only 10 metres or so from the athletics track and football pitches.
"There are lots of cars and lots of dust flying around, so it's not good at all," said Adèle, who goes running there twice a week.
"I cough, it itches in my throat and then it can turn into an asthma attack," she told news broadcaster Franceinfo.
Another local resident, Anatole, plays football near the ring road every week. He said the pollution affects his performance: "I don't play as long and if I smell the pollution, I can get a bit dizzy."
Report sounds warning over extreme heat at Paris Olympics
Athletes at risk
"When you do sport, you breathe in four to ten times more pollutants than when you are at rest," said Tony Renucci, director of Respire.
That can increase the risk of developing cardiovascular and respiratory diseases.
"If we have pollution peaks during the Olympics, we'll have to ask ourselves whether we should postpone certain disciplines," he warned.
Mapping pollution in Paris metro reveals three stations in the red
In a sign organisers have taken note of the capital's air problems, the Olympic Village, which is also built close to the ring road in the northern Paris suburb of Saint-Ouen, is equipped with air purifiers – a first.
Five experimental outdoor air filters have been installed in a bid to filter out dangerous particles.
The village welcomed the first of 10,000 Olympians on Thursday ahead of the start of the Paris Games on 26 July.