POLLUTION
2 particularly at risk. “However, researchers are finding that air pollution may be associated with a much wider range of health conditions,” she says. These include diabetes and neurological disease. Unborn babies can even be affected.
Davies is one of many leading health experts now calling for action. The National Institute for Health and Care Excellence (NICE) has recently unveiled draft proposals on how to tackle the issue, following legal action against the UK government, which has been found to be in breach of European standards for air quality.
HAZY DAYS The resurgence of public concern about air pollution has been sparked by the scandal surrounding diesel cars built by Volkswagen. In 2015, the US Environmental Protection Agency (EPA) revealed that the German-based manufacturer had fitted its vehicles with technology that sensed when the car was undergoing an emissions test, and altered its performance to ensure compliance. But once on the road, the car reverted to its normal performance – and far higher emissions of oxides of nitrogen (NOx), one of the pollutants now prompting concern. Yet the scandal came as little surprise to air quality experts. According to Prof Alastair Lewis of the University of York, scientists had expected NOx levels to be declining in city centres as old vehicles were replaced by new, supposedly cleaner ones. “But this was based on cars emitting NOx at the rates suggested by the manufacturers’ test data,” explains Lewis. Following EPA’s revelations, the reason why there had been no decline was all too obvious.
NOx is not the only, or even most harmful, form of pollution emitted by diesel engines. They also spew out so-called particulate matter (PM), tiny specks of carbon laced with organic compounds
While there have been schemes to aempt to clean up London’s air, one road in the city still exceeded 2017’s annual air pollution limit in just five days
LEFT: In the 1950s, London’s choking ‘pea-souper’ smogs were caused by burning coal as fuel. While the city’s air looks clearer today, it’s still laden with pollutants – this time from vehicle emissions like sulphates and metals. Short-term PM exposure causes acute irritation to the eyes, throat, nose and lungs, while people with conditions like asthma can suffer more severe symptoms. But long-term exposure can pose a broader risk, says respiratory medical expert Prof Anthony Frew of the Royal Sussex County Hospital, Brighton: “There’s data suggesting that diesel particles can leave people more prone to allergic responses, and promote inflammation of the airways.”
Studies suggest that PM may pose a particular risk to the elderly and those with heart disease. “It can cause cardiac rhythm issues – though we don’t know if the effect happens immediately on exposure, or takes some time,” says Frew.
Mystery also surrounds the long-term effects of exposure. In a study of the health of over 360,000 people in England and Wales, a team led by Dr Anna Hansell of Imperial College London found that exposure to pollution in the 1970s still
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