May 1, 2018

expert reaction to new WHO global air pollution data

The World Health Organization (WHO) has published new figures on air pollution.

Prof Anthony Frew, Professor of Allergy & Respiratory Medicine, Royal Sussex County Hospital, said:

“7 million deaths a year is a very broad brush estimate – in most cases air pollution is a contributory factor not the primary cause of death, so it is always very difficult in the individual case to know whether air pollution is responsible.  That is why we normally we talk about air pollution shortening lives and numbers of years of life lost and we avoid saying things like ‘air pollution kills x thousand people per year’.

“In the UK, people are living longer and healthier lives than ever before.  Air pollution levels in the UK have declined year on year since the 1950s and we are well on track to meet our self-imposed obligations under the Gothenburg agreements.

“This work is mainly about people living in the developing world, where biomass cooking fuels are a definite health hazard for women and children.

“Another important areas of concern is air pollution in China and other rapidly emerging economies, where industrialisation comes at the costs of increased burning of fossil fuels.  We still have a responsibility here – we have closed down our manufacturing plants and have exported most of the work and the associated pollution to the developing world.  So people in the developing world suffer from air pollution that is generated by industry that brings us cheap technology from China, Vietnam etc.  Moreover those industries contribute to global warming so we need to look at renewable forms of energy to power industries throughout the world.

“This report is a timely reminder that we in the West need to remember that we are lucky to live where we do, but our prosperity is built in part on polluting industries elsewhere in the world which impact on other people’s health.”

Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:

“This is the latest in a series of regular updates from WHO on the effects of air pollution on human health.  It’s generally an impressive piece of work, and demonstrates clearly the huge global impact of air pollution.  While we do still need to continue to take action on air pollution in richer Western cities like London, the position is far worse in lower and middle income countries and in many other parts of the world.  Air pollution inside the home, mainly from burning cooking fuels, causes almost as many deaths globally as air pollution outside in the environment, but dirty air from cooking is hardly an issue in countries like the UK.  WHO seem not yet to have published updated figures on deaths linked to air pollution by country, but the most recent available (for 2012) give the UK death rate from household and ambient air pollution as 24.7 deaths per 100,000 people per year, which is well below the Europe average, and only a fifth of the very high level in India and a sixth of the level in China.  We must not be complacent about UK air pollution, but in global terms, things really aren’t at all bad here.

“There are some issues to bear in mind about these WHO data.  Though the WHO scientists will have taken great care in trying to interpret the data in a consistent way, there will be large differences between countries and cities in data availability and data quality, and the coverage of air quality monitoring varies hugely between different parts of the world.  Some estimates will inevitably be a lot more accurate than others.  The WHO documentation on the methods that they use describes how they have put figures on the uncertainty in their estimates, but the data that have been made available so far appear not to include these figures on uncertainty.  So in fact the true global figures on numbers of deaths attributable to air pollution could be considerably higher than those reported here, or considerably less, and I can’t say how much higher or lower they might plausibly be – but they must still be high enough to indicate an important global health problem.  A related issue is that it’s difficult to use these figures to get a picture of how things are changing over time.  WHO do publish similar figures every few years, but their data sources also change, and the WHO scientists keep improving the way they estimate the health effects of pollution from the data, so that the resulting figures from one year are hard to compare with those from previous revisions.”

* ‘Launch of new global data and comprehensive estimates on air pollution’ was published by the WHO on Tuesday 1 May 2018.

Declared interests

Prof Anthony Frew: “I have no relevant interests to disclose.”

Prof Kevin McConway: “Kevin McConway was the lead author of a chapter on Measurement and Communication of Health Risks from Pollution for the 2017 Annual Report of the Chief Medical Officer ‘Health Impacts of All Pollution: what do we know?’. He is a member of the Science Media Centre’s Advisory Committee.”