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
Have you tried new the Independent Digital Edition apps?
ebooksA celebration of British elections
Arts and Entertainment
No Offence
tvReview: No Offence has characters who are larger than life and yet somehow completely true to life at the same time spoiler alert
Arts and Entertainment
Sarah Lucas, I SCREAM DADDIO, Installation View, British Pavilion 2015
artWhy Sarah Lucas is the perfect choice to represent British art at the Venice Biennale
Arts and Entertainment
Billie Piper as Brona in Penny Dreadful
tvReview: It’s business as usual in Victorian London. Let’s hope that changes as we get further into the new series spoiler alert
Chuck Norris pictured in 1996
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

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

iJobs Job Widget
iJobs General

SThree: Trainee Recruitment Consultant - Dublin

£13676.46 - £16411.61 per annum + OTE: SThree: SThree Trainee Recruitment Cons...

Ashdown Group: Marketing or Business Graduate Opportunity - Norwich - £22,000

£18000 - £22000 per annum + training: Ashdown Group: Business and Marketing Gr...

SThree: Trainee Recruitment Consultant

£20000 - £25000 per annum + Commission: SThree: Are you great at building rela...

Ashdown Group: Database Analyst - Birmingham - £22,000 plus benefits

£20000 - £22000 per annum + excellent benefits: Ashdown Group: Application Sup...

Day In a Page

General Election 2015: Ed Miliband's unlikely journey from hapless geek to heart-throb

Miliband's unlikely journey from hapless geek to heart-throb

He was meant to be Labour's biggest handicap - but has become almost an asset
General Election 2015: A guide to the smaller parties, from the the National Health Action Party to the Church of the Militant Elvis Party

On the margins

From Militant Elvis to Women's Equality: a guide to the underdogs standing in the election
Amr Darrag: Ex-Muslim Brotherhood minister in exile still believes Egypt's military regime can be replaced with 'moderate' Islamic rule

'This is the battle of young Egypt for the future of our country'

Ex-Muslim Brotherhood minister Amr Darrag still believes the opposition can rid Egypt of its military regime and replace it with 'moderate' Islamic rule, he tells Robert Fisk
Why patients must rely less on doctors: Improving our own health is the 'blockbuster drug of the century'

Why patients must rely less on doctors

Improving our own health is the 'blockbuster drug of the century'
Sarah Lucas is the perfect artist to represent Britain at the Venice Biennale

Flesh in Venice

Sarah Lucas has filled the British pavilion at the Venice Biennale with slinky cats and casts of her female friends' private parts. It makes you proud to be a woman, says Karen Wright
11 best anti-ageing day creams

11 best anti-ageing day creams

Slow down the ageing process with one of these high-performance, hardworking anti-agers
Juventus 2 Real Madrid 1: Five things we learnt, including Iker Casillas is past it and Carlos Tevez remains effective

Juventus vs Real Madrid

Five things we learnt from the Italian's Champions League first leg win over the Spanish giants
Ashes 2015: Test series looks a lost cause for England... whoever takes over as ECB director of cricket

Ashes series looks a lost cause for England...

Whoever takes over as ECB director of cricket, says Stephen Brenkley
Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

Fishing is on Nigel Farage's mind

Ukip leader casts a line to the disaffected
Who is bombing whom in the Middle East? It's amazing they don't all hit each other

Who is bombing whom in the Middle East?

Robert Fisk untangles the countries and factions
China's influence on fashion: At the top of the game both creatively and commercially

China's influence on fashion

At the top of the game both creatively and commercially
Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

The man known as GOD has a reputation for getting the job done

Lord O'Donnell's three principles of rule
Rainbow shades: It's all bright on the night

Rainbow shades

It's all bright on the night
'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

Bread from heaven

Dutch survivors thank RAF for World War II drop that saved millions
Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

How 'the Axe' helped Labour

UK will be 'run for the wealthy and powerful' if Tories retain power