Out of the Fifties smog and into the Nineties exhaust fumes
Steve Connor is the Science Editor of The Independent. He has won many awards for his journalism, including five-times winner of the prestigious British science writers’ award; the David Perlman Award of the American Geophysical Union; twice commended as specialist journalist of the year in the UK Press Awards; UK health journalist of the year and a special merit award of the European School of Oncology for his investigative journalism. He has a degree in zoology from the University of Oxford and has a special interest in genetics and medical science, human evolution and origins, climate change and the environment.
Friday 05 May 1995
The first sign that something serious was happening came when casualty wards began filling up with people complaining of breathing difficulties and heart problems. The second was when undertakers began to run out of coffins and florists had trouble meeting the demand for wreaths.
The worst comparable air pollution incident in recent times occurred in December 1991, again in London and again during the same weather conditions - still, cold air trapped close to the ground - that helped to cause the 1952 disaster. A similar statistical analysis concluded that about 160 extra people had died of respiratory or cardiovascular problems, probably but not necessarily as a result of poor air quality.
Even during this exceptionally dirty episode, when levels of nitrogen dioxide from car exhausts reached twice the limits recommended by the World Health Organisation, the number of casualties was far smaller than in 1952. Some scientists point out that the figure of 160 extra deaths is just on the limits of what would be statistically significant for a city with a population of millions.
Air pollution in the 1990s is very different from the choking, sulphurous smogs of 40 years ago. Now the principal problems stem from the nitrogen dioxide and extremely fine particles emitted principally from car exhausts. An additional problem in sunny weather is the production of ground-level ozone, an extremely irritant gas for the lungs, as a result of a complex cocktail of chemical reactions produced by the action of sunlight on car fumes.
Jon Ayres, consultant in respiratory medicine at the Heartlands Hospital, Birmingham, and an adviser to the National Asthma Campaign, says there is a lot of ''guesswork'' about what effect this form of pollution has on health. There is no doubt that ground-level ozone can trigger asthma attacks but usually only in sufferers who are already more severely prone to attacks anyway.
Even at high levels of ozone, Dr Ayres says, people do not flood into casualty wards in the way they did in the 1950s. The problem is ''very often overstated''.
The extremely fine particles of today's airborne pollution - 10 millionths of a metre in diameter - are causing an additional health concern. These particles, mostly emitted in vehicle exhausts, are made of a wide variety of materials and can find their way deep into the lungs, where they may cause intense irritation resulting in inflammation and breathing difficulties.
David Coggon, a respiratory scientist at the Medical Research Council's Environmental Epidemiology Unit in Southampton, says that although there is an association between fine particles and respiratory or cardiovascular disease, ''it is not always consistent.
''We're just not in a position where we can say unequivocally that fine particles are the cause of a specific disease. But the evidence indicates that there seems to be a problem.''
The real difficulty with present-day air quality is finding out whether there are serious long-term effects on health. The extra 160 deaths in 1991 could have happened anyway a few weeks or months later because these people may already have been seriously ill.
Air pollutants are not the health risk that some pressure groups make them out to be, Dr Coggon says. ''Some individuals do experience symptoms but the effects are very small compared to, say, the health effects of smoking. The general public has a rather distorted view of the health risk of air pollution.''
The public is genuinely worried about the rise in asthma among children and the corresponding increase in the level of traffic pollution. But the science of cause and effect is not simple and more work needs to be done to resolve the issue. However, whatever the health risks from today's air pollution they are not as great as they were 40 years ago, before clean-air legislation.
- 1 Bill Clinton portrait features Monica Lewinsky reference, artist admits
- 2 Delhi bus rapist blames dead victim for attack because 'girls are responsible for rape'
- 3 Pornhub turns masturbation into energy in bid to save the planet
- 4 Have sex with your iPad thanks to the new sex toy no-one asked for
- 5 Average penis size revealed: Scientists attempt to find what is 'normal' to reassure concerned men
Bill Clinton portrait features Monica Lewinsky reference, artist admits
Delhi bus rapist blames dead victim for attack because 'girls are responsible for rape'
The 'sex selfie stick' lets you FaceTime the inside of a vagina
Kanye West gives guest lecture at Oxford University: 'If I, Kanye West, can remove my ego, I think there's hope for everyone'
'This is what Islam tells us to do': A rare glimpse inside a Saudi Arabian prison – where Isis terrorists are showered with perks and privileges
New theory could prove how life began and disprove God
'Jihadi John': CAGE representative storms off Sky News accusing Kay Burley of Islamophobia
This is what it's like to be dead, according to a guy who died for a bit
Ukip would cut billions from Scottish budget to fund English tax cuts
Durham Free School: 'Creationism taught at' free school facing closure
Nearly 100,000 of Britain's poorest children go hungry after parents' benefits are cut
£15000 - £18000 per annum: Recruitment Genius: This is a great opportunity for...
£38000 - £48000 per annum: Recruitment Genius: This B2B content marketing agen...
£50000 - £60000 per annum + Excellent Salary: Austen Lloyd: An outstanding new...
£35000 - £45000 per annum: Recruitment Genius: An Infrastructure Architect is ...