As London prepares for the start of the Olympic Games on the 27th July, environmentalists and health officials alike have raised concerns that the performance of the athletes could be negatively affected by local air quality.
Air pollution has been linked with adverse health effects in London since the 1952 smog event, which was responsible for 4000 excess deaths.
The UK’s air quality is relatively poor in comparison to some other European countries.
See Figure 1 to the left for the excessive amounts of Nitrogen Dioxide (NO2) for example. A recent report has shown that over 85% of England’s worst air quality areas are in London (Figure 2.)
The effect of air pollution on athletes has been a concern since the 1984 Los Angeles Olympics, when British Steve Ovett collapsed following the 800m final with respiratory problems. He cited air pollution as a major contributing factor to his episode of exercise-induced asthma.
Which Air Pollutants are Linked With Poor Health?
Research has highlighted a number of pollutants of concern for performance athletes and the general public. These include particulate matter (PM), nitrogen and sulphur oxides, the ammonium ion, organic aerosols, and ozone. PM10 (particulate matter 10 µm and under) corresponds to particles with a diameter of about a tenth of an adult human hair and smaller, and can be breathed deep into the lung. In urban areas these particles originate from sources including traffic and industry. In the UK, exposure to these particles was found to be responsible for an average life loss from birth of 6 months.
How Could Athletes be Affected at the Olympic Games?
Potential health problems resulting from exposure to air pollutants during exercise include cardiovascular complaints, decreased performance, asthma, decreased lung function, and pulmonary hypertension. Athletes are especially susceptible to health effects from air pollution for four main reasons:
- During exercise an increased volume of air is inhaled in comparison to periods of rest.
- In response to this exertion, more air is inhaled through the mouth than when at rest. The mouth lacks the filter systems of the nose which remove pollution before it can reach the lungs.
- The increased air flow during exercise means that pollutants travel deeper into the lung.
- The fraction of particulate matter that is deposited during exercise (i.e. during increased tidal volume) is higher than during periods of rest (i.e. lower tidal volume).
The most common chronic medical condition among athletes is asthma (or airway hyper-responsiveness), with about 8% of athletes affected. Air pollution has been found to impact athlete performance, and this is especially the case for those with asthma. Poor air quality could both exacerbate symptoms and trigger attacks. The effect is greatest for outdoor endurance athletes – in a number of cases, athletes who did not suffer from asthma in their childhood went on to develop asthma following years of athletic training. A 20 minute exposure to a high-PM environment has been found to reduce performance in a six minute cycle ergometer ride which followed it, and a recent study which investigated marathon times and the link with air pollution has shown that women have a greater vulnerability to this issue.