Smog, I see no smog: As you pant your way through London - oh the heat, the crowds, the grime, the smog - take no comfort from the fact that nobody who matters is doing much about it in a hurry.

The Government's first summer smog alert of the year, on 1 July, provoked abundant press coverage, most of it appearing at least a day after the smog had dispersed. The Department of the Environment, alarmed by what it saw as an over-reaction, put out only the most timid of alerts this time round, suggesting that drivers consider not using their cars unnecessarily. Yesterday a break in the weather blew and rained away the worst summer smog this year, an event that the Government's air quality monitoring service described as 'extreme'. It will be back.

The Government's view is that these unpleasant conditions are nothing new; they usually happen a few times each summer. All new petrol cars have to be fitted with catalytic converters and the European Union is tightening standards for diesel vehicles, so pollution levels should gradually drop in the late 1990s.

It is, after all, worse on the Continent. With less wind than Britain, and a greater concentration of pollution sources, winter and summer smogs in such cities as Athens, Milan and Naples can outchoke the worst air that London has to offer. Drastic traffic curbs have sometimes been necessary.

Critics point out that further smog-busting policies will be needed if there is to be even the slightest chance of guaranteeing an air quality standard of 50ppb of ozone through the summer. And tighter standards for new vehicles do nothing to tackle today's foul air.

Roger Higman, of Friends of the Earth, said that when there is a pollution alert, John Gummer, Secretary of State for the Environment, should make the warning himself and explicitly ask the public to share or forsake their cars except for the most essential journeys. He and his ministers should take a lead by using public transport, foot or bicycle for the duration.

Labour's environment spokesman Chris Smith, MP for Islington and Finsbury, unveiled an anti-smog package this week. One proposal would reduce the annual tax disc charge for car owners who fit catalytic converters to the millions of older cars which never had them fitted as standard.

In the Old Kent Road, Southwark Borough Council now has infra-red monitoring equipment which can instantly detect pollution levels from individual vehicles then photograph their number plates if they exceed certain levels.

Since a small proportion of badly tuned and serviced vehicles are to blame for much of the pollution, there is a strong case for warning and even fining the owners of these vehicles. But legislation for this does not exist. Why, one might ask, is a London borough having to pioneer this technology in Britain rather than the Government?

But whenever there is still, high-pressure air and long hours of sunshine, traffic will cause pollution levels in and around the capital to lurch upwards. Asthmatics and others with chest illness will wheeze and feel distressed. And motorists will drive on regardless, not giving a hoot.

We can no longer claim ignorance of smog. London and the rest of the country now has a long overdue but half decent air quality monitoring network and a rudimentary pollution forecasting service, making the information available for anyone who wants it.

Weather forecasts in newspapers and on television now warn when poor air quality threatens. Ring a free government telephone number and recorded male and female voices will tell you how bad the air is now and whether it is getting worse or better (although the information can be out of date - it was yesterday morning). The television text services cover the same ground.

But how to respond to this information? There is little the victims can do. Government advice for asthmatics and others with chest illnesses is to avoid strenuous exercise when air quality is poor, increase your treatment and talk to your doctor. A government report on ozone published this April estimated that about one person in 10 was sensitive to high ozone levels.

When raised concentrations occur across much of the country, as happened on Monday and Tuesday, then a million or more asthmatics already struggling because of high pollen counts will suffer extra discomfort and shortness of breath. This highly reactive gas is known to worsen the symptoms of those with pollen allergies.

The damage done by the mixture of pollutants in summer smogs goes deeper, with a strong likelihood of long term health effects for some. Many scientists believe high nitrogen dioxide (NO2) and ozone levels are part of the explanation for the marked increase in childhood asthma, although other factors such as changes in diet, family size and indoor pollution are also implicated.

Microscopic particles of soot, produced mainly by large diesel vehicles (and the growing number of diesel cars) are small enough to penetrate deep into the lungs. Evidence of a link between levels of these particulates and extra deaths from heart disease, chest illness and cancer is accumulating.

London's diesel and petrol traffic is Britain's biggest smog factory, with fumes from petrol pumps, industrial solvents and power station emissions all adding their bit. In an anticyclone the high pressure air moves only sluggishly over the city, with levels of pollutant gases and particulates building up steadily below 3,000 feet.

Add strong sunshine, and a complex series of light-powered chemical reactions begins to cook this atmospheric soup, leading to the formation of corrosive ozone over several hours.

By then the air will have moved on a little, so ozone levels are just as high in the surrounding countryside as in the city. They may well be slightly higher in the suburbs and countryside because one pollutant in vehicle exhaust, nitrous oxide, destroys ozone in the short term.

Ozone levels usually reach their peak in the afternoon and early evening, after the sun has had time to do its work. Concentrations of nitrogen dioxide, the most important initial pollutant, march along with the traffic; on Tuesday they were highest just after the morning rush hour.

The four central London monitoring stations all picked up NO2 levels well above 100 parts per billion (ppb) - the point at which 'poor air quality begins. The highest - 138ppb at a kerbside site in the Cromwell Road.

Out at Bexley in south-east London, the ozone level hit 109ppb at 7pm. 'Poor starts at 90ppb for ozone. Beyond the M25, levels were still higher - 113ppb was Tuesday's highest reading in Britain, at the monitoring station in Suffolk.

To put this in context, a government-appointed panel of experts recommended a UK ozone limit of 50ppb earlier this year. A World Health Organisation guideline holds that ozone levels should not exceed 50ppb for more than eight hours. They certainly did over large parts of Britain on Monday and Tuesday.

So why do drivers drive on through smogs? Selfishness and a lack of alternatives are part of the answer, but Friends of the Earth argues that it's also because the Government gives little leadership and puts out feeble warnings.

On Tuesday afternoon at the Department of the Environment's Marsham Street headquarters only four civil servants had put their names down on a list offering to share their cars with colleagues. And that pooling scheme had been set up to combat the signalmens' strike rather than smog.

HOW THEY MEASURE THE TOXINS

Earlier this year, noxious sulphur dioxide pollution measured by Barking and Dagenham Council was bad enough to be classed as poor air quality by the

Department of the Environment, but across the city at the Government's official monitoring stations in Bloomsbury, Victoria, Earls Court and Cromwell Rd, South Kensington, sulphur dioxide levels were safely in the good air quality band. So despite poor air quality being a trigger for issuing health warnings, the

people of East London were not informed.

'To say that air quality in London is good when we find that it's poor in certain areas is misleading. People living in those areas may suffer from air pollution unnecessarily, says John Rice of the London Air Quality Network.

Co-ordinated by the South East Institute of Public Health, the London Boroughs Association and the Association of London Authorities, the London Air Quality Network set out to provide comprehensive air quality data for the whole of London.

Its first report highlights the significant differences in air pollution levels experienced over London. Data collected from monitoring sites run by local authorities in 1993 showed air pollution incidents missed by official stations occurred in Bromley, Bexley, Hounslow and Southwark. In these areas, air pollutants exceeded World Health Organisation guidelines.

According to the LAQN, the need for data at a local level was obvious. It now runs monitoring sites in Hackney, Hounslow, Westminster, Islington, Wandsworth and Barking and Dagenham. But as the LAQN is not resourced to deal with enquiries, information can only be obtained through local councils.

Under pressure from the LAQN and its own advisers, the Government is now considering broadening its monitoring system to include local sites. Sulphur dioxide pollution levels regularly above health guidelines in Bexley have already led to the inclusion of the site in the Government's official monitoring network.

John Rice is hoping for support from the Government, as part of an overall strategy to reduce air pollution.

'In the Fifties and Sixties, the government successfully reduced smog by working through local authorities. That is the approach we need today.

Karen L. McVeigh

(Photograph omitted)