Study by Imperial College indicates health impacts of particulate air pollution last decades after exposure
The longest-running study so far – by Imperial College – has analysed long-term mortality risks of Britons exposed to historic particulate pollution. It has found that health impacts from particulate air pollution persist for years. The study did not look at NOx. The analysis of 368,000 British people over 38 years showed that those living in the most polluted places have a higher risk of dying than those in areas with the least air pollution. The deaths were from respiratory problems, like pneumonia, emphysema and bronchitis, and also from cardiovascular problems, like heart attacks. The leader of the study, Dr Anna Hansell, said there was an association between exposure to air pollution in 1971 with mortality in 2002-09. However, more recent exposures to polluted air are more harmful, with more impact from exposure to polluted air in 2001 on health in 2002 -09. “There is an imperative that, because the effects are so long-lasting, we really ought to act on it. We have to think about what we are doing to the long-term health of the population.” There are 29,000 premature deaths per year in the UK – or 5% of all deaths – blamed on air pollution. The impact of particulate air pollution on children, whose lungs can be stunted for life, has been of particular concern to experts.
Air pollution raises risk of death ‘for decades after exposure’
By Damian Carrington (Guardian)
Longest-running study to date analyses long-term mortality risks of Britons exposed to historic particulate pollution [ Link to the study ]
High pollution levels were recorded in London in late January. The new study shows that health impacts from air pollution persist for a long time.
Air pollution raises the risk of death for many decades after exposure, according to the longest-running study to date.
The analysis of 368,000 British people over 38 years also showed that those living in the most polluted places have a 14% higher risk of dying than those in the least polluted areas.
Those exposed to particulate air pollution were more likely to die from respiratory problems, like pneumonia, emphysema and bronchitis, and also from cardiovascular problems, like heart attacks.
“What this study shows is that the [health] effects of air pollution persist for a very long time,” said Dr Anna Hansell, at Imperial College London, who led the new study. “There is an imperative that, because the effects are so long-lasting, we really ought to act on it. We have to think about what we are doing to the long-term health of the population.”
Many Britons are currently exposed to illegal levels of air pollution, with 29,000 premature deaths a year – or 5% of all deaths – blamed on air pollution. The UK government lost a supreme court legal battle in 2015 and was forced to produce an action plan.
If successful, this will cut air pollution to legal levels by 2020 in most cities and 2025 in London. The impact on children, whose lungs can be stunted for life, has been of particular concern to experts.
The truth about London’s air pollution Read more
The new research, which is published in the journal Thorax on Tuesday, selected individuals at random from anonymised Office of National Statistics data and tracked them via the national censuses in 1971, 1981, 1991 and 2001. The study also estimated their exposure over time to particulate air pollution, which is produced mainly by the burning of fossil fuels in power stations and by vehicles.
“We found a statistically significant association between [air pollution] exposure in 1971 and mortality in 2002-09,” said Hansell. The risk of death rises by 2% for each extra unit of pollution (10 micrograms of particulates per cubic metre) a person was exposed to in 1971.”
Hansell added: “The more recent exposures appear to be the more harmful to health.” For each extra unit of pollution exposure in 2001, the risk of death in 2002-09 rises by 24%.
Hansell said this gave another urgent reason to reduce air pollution, as cuts now would improve health in the next few years as well as in the long term.
The reason the risk of death falls with time since the exposure is probably because the health impacts of air pollution fade over time, said Hansell, although the different mix of pollutants today compared to 1971 might be more toxic.
The researchers found that the 36,800 people exposed to the highest levels of air pollution had a 14% greater risk of dying than those exposed to the lowest levels of air pollution. By coincidence, that applied to exposure in both 1971 and in 2001, although overall particulate pollution levels have fallen significantly – about 80% – in the decades between.
Gary Fuller, an air pollution expert at King’s College London and not part of the new new study, said: “It feeds into the developing body of evidence about air pollution affecting us throughout the course of our lives. It increases the imperative for action to reduce the way in which the air that we breathe today can compromise our health and our children’s health later in life.”
The research did not assess the impact of nitrogen dioxide, a toxic pollutant present at very high levels in some of the UK’s cities, which is linked to the failure of car manufacturers including Volkswagen to produce cars with emissions below official limits in real driving conditions.
Hansell said: “It’s important to remember that the effects of air pollution are small compared to other risk factors. Your risk of dying early is much more dependent on other aspects of your lifestyle, like whether you smoke, how much you exercise and whether you are overweight.”
In the study, those who died in accidents or could not be traced in later censuses were excluded. The researchers adjusted the data for the effect of age, sex, and social deprivation.
They also accounted for lung cancer deaths, which are strongly related to smoking, but this made little difference to the conclusions.
“Historic air pollution exposure and long-term mortality risks in England and Wales: prospective longitudinal cohort study”
8.2.2016 in Thorax
Long-term air pollution exposure contributes to mortality but there are few studies
examining effects of very long-term (>25 years) exposures. ….. This large national study suggests that air pollution exposure has long-term effects on mortality that persist decades after exposure, and that historic air pollution exposures influence current estimates of
associations between air pollution and mortality.
This study suggests that air pollution exposure may have persistent long-lasting impacts on mortality risk but that more recent air pollution exposures is associated with higher relative risks than past exposures. Concentration–response function estimates for recent long-term exposures may be slightly overestimated if previous exposures are not taken into account. Findings may be particularly relevant to countries such as China experiencing high but declining levels of particulate concentrations, with a transition from coal to cleaner fuels and increases in emissions from traffic
DEFRA produces plan to improve air quality – Client Earth regards it as inadequate
A ruling by the Supreme Court in April 2015 required the government to produce a comprehensive plan to meet air pollution limits by December. The government has now produced this. The intention is that it has to include low emission zones, congestion charging and other economic incentives. It is thought that due to the failure to meet European limits of harmful NOx gases, which are mostly caused by diesel traffic, there are up to 9,500 premature deaths each year in London alone. Under the government’s plan, “Clean Air Zones” will be introduced – by 2020 – in areas of Birmingham, Leeds, Nottingham, Derby and Southampton where pollution is most serious. However, though vehicles like old buses, taxis, coaches and lorries have to pay a charge to enter these zones – private passenger cars will not be charged. Also newer vehicles that meet the latest emission standards will not need to pay. Client Earth, the lawyers who brought the legal case against the UK government, for breaching the EU’s Air Quality Directive, said the plan falls far short of the action necessary to comply with the Supreme Court ruling, and they will make a legal challenge to force the government to take faster action to achieve legal pollution limits. “As soon as possible,” or by 2020, is not soon enough.
Environmental Audit Committee says Government must ensure legal air pollution limits can be met and maintained
The Environmental Audit Committee report on a Heathrow runway, says in relation to air pollution: “Before the Government makes its decision, it should make its own assessment of the likely costs of preventing an adverse impact on health from expansion at Heathrow and publish it.” Also that the government should not consider a new runway merely if air quality could be worse elsewhere in London than in the Heathrow area. The government will need to demonstrate that legal air pollution limits can be met and maintained “even when the expanded airport is operating at full capacity. Heathrow’s existing air quality strategy should also be revised to meet the new targets. Failing this, Heathrow should not be allowed to expand.” As for not using the new runway if air quality is too poor: “The Government should not approve expansion at Heathrow until it has developed a robust framework for delivery and accountability. This should have binding, real-world milestones and balance the need for investor certainty with assurances that a successor Government cannot set the conditions aside if they become inconvenient.” In distinguishing pollution from the airport, or from other sources: “The Government must establish clearly delineated responsibilities for meeting air quality limits before deciding to go ahead with the scheme” to avoid future legal and commercial risks.