On 26 April 2026, the London Marathon did something it had never done before. Every one of its 59,000 runners had access to real-time air quality data. For the first time, AirTrack was there providing route insights for elites, a live app for all participants, and data on the big screen at the Green Team start.

The invisible performance variable

‍When you run, you breathe 10 to 20 times more air per minute than at rest. That means whatever is in the air around you enters your body at a much faster rate, bypassing the nose’s natural filters and reaching deep into the lungs.

• 32 seconds slower per 1 µg/m³ rise in PM2.5 for male runners
• Around 1.5 percent slower finish times linked to elevated PM2.5 during training
• 46 percent of the global population live in areas where PM2.5 can cancel out the benefits of exercise

These are not abstract statistics. For the runners on the start line, from sub-elite club runners to first-timers, air quality is a real variable that affects both health and performance.

What we delivered‍

Elite route insights: in the days before the race, we provided elites with personalised data on the best training routes and times, helping them make smarter final-week decisions around pollution peaks.

Live app for all runners: a bespoke race-day app gave every participant access to hyperlocal, real-time air quality data from the course itself, not city-wide averages.

Green Team start screen: air quality information was displayed on big screens, bringing the data to runners at the moment it mattered most.

What the data showed

‍London is, relatively speaking, a strong city for marathon running, and the event makes it even better. Road closures typically reduce traffic by 40 to 50 percent in and around the route. The main pollutant of concern going into race week was ozone due to the heat, whilst particulate matter and nitrogen dioxide were lower thanks to the local road closures and high dispersion from winds. The slower runners, who started later in the day, were those most impacted by the higher temperatures and ozone levels.  

“After writing about the impact of high ozone for years, having the race organisers come to us was a full-circle moment.” - Louise Thomas, CEO and co-founder

A first of many‍

Sebastian Sawe broke the two-hour barrier on the London course, a world record and historic first. It was also the first year the London Marathon provided air quality data and cleaner routes for the elite runners to access taper runs.   Both belong in the same conversation about what becomes possible when athletes have access to better information.

The Athletics for a Better World standard now includes air quality as a requirement for global events. London should be at the front of that movement. This year’s partnership is, we hope, the first step.

Go deeper

→ Marathon page: air quality and long-distance running

→ Live race-day app

→ AirTrack app: know your air

→ Article about three years of London Marathon air quality data

→ The science and research on athletes and air pollution

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Join us on our mission to personalise air quality, for everyone.