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.

Arts & Entertainment
A stranger calls: Martin Freeman in ‘Fargo’
tvReview: New 10-part series brims with characters and stories

Arts & Entertainment
Shaun Evans as Endeavour interviews a prisoner as he tries to get to the bottom of a police cover up
Review: Second series comes to close with startling tale of police corruption and child abuse
Sport
Raheem Sterling and Luis Suarez celebrate during Liverpool's game with Norwich
football Another hurdle is out of the way for Brendan Rodgers' side
Arts & Entertainment
Charlotte Brontë, the English novelist, poet and the eldest of the three Bronte sisters who lived into adulthood, has been celebrated with a Google Doodle depicting her most famous novel, Jane Eyre.
arts + ents "Reader, they doodled her".

VIDEO
Have you tried new the Independent Digital Edition iPad app?
Arts & Entertainment
Schwarzenegger winning Mr. Universe 1969
arts + entsCan you guess the celebrity from these British Pathe News clips?
News
Portrait of Queen Elizabeth-II by David Bailey which has been released to mark her 88th birthday
peoplePortrait released to mark monarch's 88th birthday
Arts & Entertainment
The star of the sitcom ‘Miranda’ is hugely popular with mainstream audiences
TVMiranda Hart lined up for ‘Generation Game’ revival
Life & Style
The writer, Gerda Saunders, with her mother, who also suffered with dementia before her death
healthGerda Saunders on the most formidable effect of her dementia
Sport
Manchester United manager David Moyes looks on during his side's defeat to Everton
footballBaines and Mirallas score against United as Everton keep alive hopes of a top-four finish
Sport
Tour de France 2014Sir Rodney Walker on organising the UK stages of this year’s race
Arts & Entertainment
Jessica Brown Findlay as Mary Yellan in ‘Jamaica Inn’
TVJessica Brown Findlay on playing the spirited heroine of Jamaica Inn
News
YouTube clocks up more than a billion users a month
mediaEuropean rival Dailymotion certainly thinks so
Arts & Entertainment
The original design with Charles' face clearly visible, which is on display around the capital
arts + ents
Arts & Entertainment
‘Self-Portrait Worshipping Christ’ (c943-57) by St Dunstan
books How British artists perfected the art of the self-portrait
News
People
News
Sir Cliff Richard is to release his hundredth album at age 72
PEOPLE
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Have you tried new the Independent Digital Edition iPad app?
Independent Dating
and  

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

iJobs Job Widget
iJobs General

Geography Teacher

£130 - £140 per day: Randstad Education Ilford: Secondary Geography Teacher Lo...

Do you want to work in Education?

£55 - £70 per day: Randstad Education Cheshire: Are you a dynamic and energeti...

SEN Teaching Assistant

Negotiable: Randstad Education Group: SEN TAs, LSAs and Support Workers needed...

Private Client Senior Manager - Sheffield

£50000 - £60000 per annum: Pro-Recruitment Group: The Sheffield office of this...

Day In a Page

Rubin ‘Hurricane’ Carter: The man who could have been champion of the world - and the Bob Dylan song that immortalised him

The man who could have been champion of the world

Rubin ‘Hurricane’ Carter and the Bob Dylan song that immortalised him
Didn’t she do well?

Didn’t she do well?

Miranda Hart lined up for ‘Generation Game’ revival
The Middle East we must confront in the future will be a Mafiastan ruled by money

The Middle East we must confront in the future will be a Mafiastan ruled by money

In Iraq, mafiosi already run almost the entire oil output of the south of the country
Before they were famous

Before they were famous

Can you guess the celebrity from these British Pathe News clips?
Martin Freeman’s casting in Fargo is genius

Martin Freeman’s casting in Fargo is a stroke of genius

Series is brimming with characters and stories all its own
How I brokered a peace deal with Robert Mugabe: Roy Agyemang reveals the delicate diplomacy needed to get Zimbabwe’s President to sit down with the BBC

How I brokered a peace deal with Robert Mugabe

Roy Agyemang reveals the delicate diplomacy needed to get Zimbabwe’s President to sit down with the BBC
Video of British Muslims dancing to Pharrell Williams's hit Happy attacked as 'sinful'

British Muslims's Happy video attacked as 'sinful'

The four-minute clip by Honesty Policy has had more than 300,000 hits on YouTube
Church of England-raised Michael Williams describes the unexpected joys in learning about his family's Jewish faith

Michael Williams: Do as I do, not as I pray

Church of England-raised Williams describes the unexpected joys in learning about his family's Jewish faith
A History of the First World War in 100 moments: A visit to the Front Line by the Prime Minister's wife

A History of the First World War in 100 moments

A visit to the Front Line by the Prime Minister's wife
Comedian Jenny Collier: 'Sexism I experienced on stand-up circuit should be extinct'

Jenny Collier: 'Sexism on stand-up circuit should be extinct'

The comedian's appearance at a show on the eve of International Women's Day was cancelled because they had "too many women" on the bill
Cannes Film Festival: Ken Loach and Mike Leigh to fight it out for the Palme d'Or

Cannes Film Festival

Ken Loach and Mike Leigh to fight it out for the Palme d'Or
The concept album makes surprise top ten return with neolithic opus from Jethro Tull's Ian Anderson

The concept album makes surprise top ten return

Neolithic opus from Jethro Tull's Ian Anderson is unexpected success
Lichen is the surprise new ingredient on fine-dining menus, thanks to our love of Scandinavian and Indian cuisines

Lichen is surprise new ingredient on fine-dining menus

Emily Jupp discovers how it can give a unique, smoky flavour to our cooking
10 best baking books

10 best baking books

Planning a spot of baking this bank holiday weekend? From old favourites to new releases, here’s ten cookbooks for you
Jury still out on Manchester City boss Manuel Pellegrini

Jury still out on Pellegrini

Draw with Sunderland raises questions over Manchester City manager's ability to motivate and unify his players