More than 45,000 people are thought to die each year in the UK because of air pollution
LEADERS FROM ATHENS, MEXICO CITY, PARIS AND MADRID HAVE RECENTLY ANNOUNCED THAT DIESEL VEHICLES WILL BE BANNED IN THEIR CITIES FROM 2025, DUE TO POLLUTION CONCERNS. SO WHAT EFFECT DO DIESEL EMISSIONS HAVE ON OUR HEALTH, AND SHOULD WE BE WORRIED? Words: Pr
Look outside. Perhaps it’s a bright and cold day, and you’re thinking of cycling into town. But you might want to think again. You may be about to put yourself in harm’s way from high levels of compounds at the centre of a major public health issue: air pollution.
Air pollution has long been regarded as a threat that vanished with the smoke-belching factories of yesteryear. And while the dense ‘pea-souper’ smogs of the 1950s may have gone for good, they have been replaced by invisible forms of pollution that build up on bright, still days – especially during the cooler months of the year. Exactly how such pollutants affect our health is the subject of urgent research, but there’s growing concern that they pose a major health threat. Air pollution is back at the top of the UK public health agenda, implicated in the deaths of tens of thousands of people each year.
According to Prof Dame Sally Davies, chief medical officer for England, it’s already clear that the elderly and those with pre- existing heart disease or lung disorders are
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.
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 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
affected health almost 40 years later. The team also found that while levels of air pollution are now far lower than in the 1970s, it seems to be more toxic.
Exactly why isn’t clear, and some experts have questioned the finding. Even so, there is an emerging consensus that air pollution is a major health hazard. In a report published just before the VW scandal broke, the Department for Environment, Food and Rural Affairs (Defra) put the estimated number of deaths in the UK due to oxides of nitrogen and PM at over 45,000 per year.
It’s a shocking statistic – over 25 times the annual number of fatalities on roads. But it has been backed by the Royal College of Physicians and Royal College of Paediatrics and Child Health. Their joint report issued last year stressed that the threat from air pollution has evolved over recent decades. “Everyone thought that the problem of air pollution was over. But how wrong we were,” said Prof Stephen Holgate, chair of the group which put together the study. He believes the time has come for “urgent, determined and multidisciplinary action” to tackle the threat.
Unsurprisingly, there are already calls for draconian action against diesel vehicles in cities. In November, London’s mayor Sadiq Khan called for a scrappage scheme and taxes to encourage a switch
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
Listen to So I Can Breathe, a season exploring air pollution, 6-12 March.