Environment: Smog levels in London top those in Paris

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Smogs worse than the one in Paris last week have engulfed British cities in the 1990s and are likely to do so again. Nicholas Schoon, Environment Correspondent, asks why Britain has never taken emergency measures seen in France

The media took it for granted that the foul air conditions in the French capital could never occur in British cities. But in December 1994 London experienced levels of nitrogen dioxide, a key smog pollutant, just as high as those in France, according to data in the Government's air quality archive.

That smog passed almost unnoticed - and not for the first time. The highest nitrogen dioxide level recorded in Britain was over twice the peak concentration in Paris last week. That was in December 1991, when London was smothered in highly polluted air for days of still, freezing weather.

These dirty air episodes are not confined to the capital. The archive, available on the Internet, reveals that in the past four years Birmingham, Sheffield, Newcastle, Cardiff and especially Manchester have at least once experienced nitrogen levels higher than 400 micrograms per cubic metre of air - the level which triggered the Paris car clampdown.

Such smogs happen when the air is exceptionally still, allowing the pollutants - of which traffic is now the single most important source - to accumulate in the lower atmosphere. In Britain the worst city smogs have occurred in winter.

In Paris half the city's cars - those with even numbered licence plates - were ordered off the road, while public transport became free. In Britain, central and local Government would shudder at the prospect of suddenly doing this. Who would foot the bill when so much public transport is privatised?

In theory, councils have emergency powers to shut major roads when pollution reaches health-threatening levels. They have never been used. London lacks the city-wide governing body or mayor needed to tackle the problem. The Government plans to change that, provided Londoners support the idea in a referendum.

The Government is also implementing an air quality strategy devised by its Tory predecessors. Local councils are being asked to team up with their neighbours and draw up strategies to reduce pollution levels in the worst affected cities and regions. But the British approach is to try to ensure pollutants never hit levels high enough to require drastic action to get cars off the road.

Air quality should be improving through the 1990s with the spread of the catalytic converter in cars. In fact, it shows little sign of getting any better as yet. While the average car may produce fewer emissions, there are more cars.

What was probably Britain's worst ever smog occurred in early December 1952. This ``pea-souper'' lasted for most of a week, and the murky, wet air was made so acidic by sulphur dioxide that it dissolved nylon stockings. It also seems to have affected sperm production in men for a few weeks, because just over nine months later the ratio of female to male births was shifted, briefly but firmly, towards girl babies.

Epidemiologists also noticed a sharp increase in the death rate at the time. The smog is estimated to have killed nearly 4,000 people through heart and lung disease.

Today's smogs still take lives and cause illness, but they are not as lethal. In the 1950s the major contributor to the pollution was coal, burnt in millions of households, rather than traffic.