Millions of UK runners unknowingly risk stroke and heart disease by doing this

Around six million people in the UK run regularly, with three-quarters citing health as their main motivation. But these benefits could be counteract not by speed or how often you exercise, but by where you choose to run, with around 80 per cent of runners making a mistake that could potentially increase their risk of developing respiratory problems, stroke and heart disease.

The research, carried out as part of the Otrivine Actions to Breathe Cleaner campaign, has found that eight out of 10 runners use roadside routes, with a third of those in urban areas spending the majority of their workout among traffic. This means they are breathing in high levels of air pollution, a toxic cocktail of pollutants, the dangers of which are well known.

The Government estimates long-term exposure to air pollution kills as many as 36,000 people a year, calculating that over an 18-year period.

Meanwhile, brand new research presented at the European Emergency Medicine Congress today (Wednesday), shows that emergency hospital admissions rise by 10 to 15 per cent with increased pollution — even when levels remain within World Health Organisation guidelines.

Pollutants come in two forms - gases such as nitrogen dioxide, sulphur dioxide and ammonia, and everything else, which is known as ­particulate matter, or PM. This includes natural irritants such as pollen and dust, as well as carbon, metals, rubber and compounds from brake linings and even the road surface itself.

Public Health England (PHE) warns there is no safe level of some pollutants, including particulate matter or nitrogen dioxide, and PM that is 2.5microns or smaller is particularly dangerous.

The Mayor of London, Sadiq Khan, developed late-onset asthma as a result of his exposure to air pollution while training for the London Marathon 10 years ago – and one in four city sites where air quality is tested regularly tend to breach safe limits.

The statistics underline how difficult it is to gauge pollution. Manchester has the dirtiest air, followed by London, Birmingham and South Wales.

David McEvoy, a researcher at University College Dublin and regular runner who averages 40 miles a week, explains: “These really tiny pollutants can get into our system and contain a cocktail of different pollutants.”

Worryingly, the very act of exercising vigorously increases your intake of these dangerous chemicals. His review of the evidence found that strenuous exercise can lead to a tenfold increase in the toxins inhaled, and this impairs respiratory health and lung function. Some studies show pollution also increases blood pressure and could increase the risk of heart and lung problems.

Despite these risks, 73% of runners do nothing to reduce their exposure to ­pollutants and only 14% bother to check the air quality before they run, according to a survey of runners for the Otrivine Actions to Breathe Cleaner campaign.

Esther Goldsmith, a physiologist who works with Athletics England, says: “Obviously someone is breathing faster when they are running, so they take in more air and if that air contains increased pollutants – whether that’s ozone, ­particulates or carbon dioxide – that can have a big effect on the body globally.”

People who aren’t at peak fitness are also more likely to breathe in more pollution due to their heavier breathing rate. A study that looked at marathon runners found lung deposits of particulates were 22% higher in average runners compared to elite athletes. Esther says: “You might not notice pollution unless it is really, really bad, but this pollution increases the stress your body is under. It can increase baseline inflammation and baseline oxidative stress, which are two things that really put pressure on our physiology.”

And she warns: “People who are taking up running for their health are more likely to have compromised blood pressure, cardiac function and other comorbidities. That makes it even more important to do your workout well away from any busy roads."

Here are some simple steps you can take to help reduce your exposure to pollutants:

■ Check local levels: Search your postcode on the UK Emissions Interactive map 

■ Avoid running during rush hour and when it’s hot.

■ Follow your nose: “There’s some evidence nostril breathing increases nitric oxide production, which is beneficial for cardio-vascular function and oxygen transport, and breathing through your nose can improve running economy,” Esther says. While she admits “it’s not easy to nose-breathe”, she says it’s a training strategy that delivers results for elite athletes.

■ Rinse well: Use Otrivine Saline Wash (£9.25; Boots) before a run will support nasal breathing by clearing congestion and mucus. Post-run it’s a natural way to flush out pollutants, with laboratory tests showing it clears up to 49% of urban dust and pollutants in 30 seconds.

■ Mind the gap: The amount of pollution you breathe in varies dramatically­ depending on whether you run on the roadside or away from traffic. Try to keep your distance from the road, or run on a quieter route. Running alongside tall buildings also increases the risk of breathing in pollutants, so avoid them where possible.

■ For more evidence-based advice on pollution and running from Athletics England, go to englandathletics.org/take-part/clean-air-running-with-otrivine