Out of the Fifties smog and into the Nineties exhaust fumes

It was probably the worst air pollution incident in British history. For five days in December 1952 a thick, yellowish ''pea-souper'' hung over London. By the time the pall rose, an estimated 4,000 people had died from the smog.

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.

Start your day with The Independent, sign up for daily news emails
Arts and Entertainment
Brendan O'Carroll as Agnes Brown in the 2014 Mrs Brown's Boys Christmas special
tvCould Mrs Brown's Boys have taken lead for second year?
Arts and Entertainment
Madonna is not in Twitter's good books after describing her album leak as 'artistic rape and terrorism'
music14 more 'Rebel Heart' tracks leaked including Pharrell Williams collaboration
Arts and Entertainment
Jack O'Connell stars as Louis Zamperini in Angelina Jolie's Unbroken
film review... even if Jack O'Connell is excellent
News
peopleIt seems you can't silence Katie Hopkins, even on Christmas Day...
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
ebooks
ebooksA year of political gossip, levity and intrigue from the sharpest pen in Westminster
News
news
Arts and Entertainment
Wolf (Nathan McMullen), Ian (Dan Starky), The Doctor (Peter Capaldi), Clara (Jenna Coleman), Santa Claus (Nick Frost) in the Doctor Who Christmas Special (BBC/Photographer: David Venni)
tvOur review of the Doctor Who Christmas Special
News
i100
Arts and Entertainment
tvChristmas special reviewed
Arts and Entertainment
Jenna Coleman as Clara Oswald in the Doctor Who Christmas special
tvForget the rumours that Clara Oswald would be quitting the Tardis
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Ashdown Group: Senior Marketing Executive- City of London, Old Street

£40000 - £43000 per annum + benefits: Ashdown Group: Senior Marketing Executiv...

Ashdown Group: Marketing Manager

£40000 - £43000 per annum + benefits: Ashdown Group: An international organisa...

Ashdown Group: Internal Recruiter -Rugby, Warwickshire

£25000 - £30000 per annum: Ashdown Group: Internal Recruiter -Rugby, Warwicksh...

Ashdown Group: Marketing Manager/Marketing Controller (Financial Services)

£70000 - £75000 per annum + benefits: Ashdown Group: Marketing Manager/Marketi...

Day In a Page

A Christmas without hope: Fears grow in Gaza that the conflict with Israel will soon reignite

Christmas without hope

Gaza fears grow that conflict with Israel will soon reignite
After 150 years, you can finally visit the grisliest museum in the country

The 'Black Museum'

After 150 years, you can finally visit Britain's grisliest museum
No ho-ho-hos with Nick Frost's badass Santa

No ho-ho-hos with Nick Frost's badass Santa

Doctor Who Christmas Special TV review
Chilly Christmas: Swimmers take festive dip for charity

Chilly Christmas

Swimmers dive into freezing British waters for charity
Veterans' hostel 'overwhelmed by kindness' for festive dinner

Homeless Veterans appeal

In 2010, Sgt Gary Jamieson stepped on an IED in Afghanistan and lost his legs and an arm. He reveals what, and who, helped him to make a remarkable recovery
Isis in Iraq: Yazidi girls killing themselves to escape rape and imprisonment by militants

'Jilan killed herself in the bathroom. She cut her wrists and hanged herself'

Yazidi girls killing themselves to escape rape and imprisonment
Ed Balls interview: 'If I think about the deficit when I'm playing the piano, it all goes wrong'

Ed Balls interview

'If I think about the deficit when I'm playing the piano, it all goes wrong'
He's behind you, dude!

US stars in UK panto

From David Hasselhoff to Jerry Hall
Grace Dent's Christmas Quiz: What are you – a festive curmudgeon or top of the tree?

Grace Dent's Christmas Quiz

What are you – a festive curmudgeon or top of the tree?
Nasa planning to build cloud cities in airships above Venus

Nasa planning to build cloud cities in airships above Venus

Planet’s surface is inhospitable to humans but 30 miles above it is almost perfect
Surrounded by high-rise flats is a little house filled with Lebanon’s history - clocks, rifles, frogmen’s uniforms and colonial helmets

Clocks, rifles, swords, frogmen’s uniforms

Surrounded by high-rise flats is a little house filled with Lebanon’s history
Return to Gaza: Four months on, the wounds left by Israel's bombardment have not yet healed

Four months after the bombardment, Gaza’s wounds are yet to heal

Kim Sengupta is reunited with a man whose plight mirrors the suffering of the Palestinian people
Gastric surgery: Is it really the answer to the UK's obesity epidemic?

Is gastric surgery really the answer to the UK's obesity epidemic?

Critics argue that it’s crazy to operate on healthy people just to stop them eating
Homeless Veterans appeal: Christmas charity auction Part 2 - now LIVE

Homeless Veterans appeal: Christmas charity auction

Bid on original art, or trips of a lifetime to Africa or the 'Corrie' set, and help Homeless Veterans
Pantomime rings the changes to welcome autistic theatre-goers

Autism-friendly theatre

Pantomime leads the pack in quest to welcome all