This summer, large-scale sporting events will take place, including the men’s football World Cup in the US, Canada and Mexico and the Commonwealth Games in Glasgow, but research reveals that such events have unexpected air pollution impacts.

About 6,000 athletes from 72 counties and nearly 3 million people attended the Birmingham 2022 Commonwealth Games, making it the UK’s largest sporting event since the 2012 London Olympics. More than 300,000 spectators went to the Alexander Stadium for the athletics events, as well as the opening and closing ceremonies.

Among the fans was an electric van packed with instruments to measure air pollution.

Dr Joe Acton, from the University of Birmingham, explained: “The van was a tight and noisy space to work. Home comforts were limited to folding chairs. It was also warm and sunny which helped produce a great atmosphere in and around the stadium, but it was very hot operating our instruments.”

Acton summarised the results: “The main surprise was particle pollution in the fan areas around the stadium. For a spectator attending a full day of events, their daily exposure would be more than doubled.”

Particle pollution peaked before each stadium session, and reached a maximum just before the closing ceremony, when it was 10 times greater than other parts of the city.

The main source was not traffic but catering, which was dominantly fast-food that included burgers, hotdogs and stir-fries. Other research, including a study of the UK’s “eat out to help out” scheme, has shown particle pollution from catering and restaurants, mainly from frying.

The catering pollution was greatest before the opening and closing ceremonies but fell quickly as spectators took their seats. There was then a second pollution peak during the firework displays. There was a different pattern during the athletics events, with prolonged pollution as people visited the catering outlets throughout the sessions.

Prof William Bloss, who led the University of Birmingham team, said: “As well as impacting staff and spectators, poor air will also impact athletic performance, making it an important issue for organisers of events like the Commonwealth Games – and for athletes seeking records.”

He said there were 34 venues in the UK with a capacity greater than that of Alexander Stadium. “Event organisers should consider the impact of cooking from concession stands, particularly for staff and volunteers who may be exposed for multiple days.”

There were two notable air pollution successes.

“There was little detectable impact from Games traffic,” said Acton. “The traffic management during the Birmingham Commonwealth Games worked from an air quality perspective. This likely reflects the emphasis on park and ride sites and public transport.”

Stadium access was limited to a small number of vehicles used to transport athletes and officials. Event tickets included free public transport, with walking routes to the venues and free cycle hire and cycle parking.

Smoking was banned at the 2022 Commonwealth Games events, and no tobacco smoke was detected. This contrasted with a 2012 study of air pollution at a German Bundesliga football match, which found that tobacco smoke was the dominant source of air pollution in the stadium.