Air pollution - fact or fiction?

Following publication of the article on benzene air pollution (May 5), I read the air quality section of the State of the Environment Report for 2002 with horror.

The poor quality of the air we breathe is directly due to the uncontrolled expansion of road traffic, with benzene, nitrogen dioxide and PM10 levels far in excess of the recommended guidelines in all built-up areas, with the bulk of the population living in the "hot spot" areas.

Mepa's subsequent report (June 28), claiming a wholesale drop in benzene levels to below guideline levels, gave initial relief. Unfortunately, this report does not stand even cursory scrutiny.

This report claims a "gradual" decrease of benzene levels over the past four years, with beautifully presented charts and graphs to illustrate the point. What the charts do in fact show is a plummeting of benzene levels from 2001 to 2002. Simple analysis of the figures presented bears this out, with no discernible difference between the figures given for the years 2000 and 2001, but a highly significant difference between 2001 and 2002. The mean level for 2002 is virtually half that of 2001. Fourteen sites exhibited severe pollution in 2000 and 2001 as opposed to only two sites in 2002. One can hardly call that gradual!

It may be pertinent to point out that WHO guidelines for benzene recommend levels below 1.5 parts per billion. The vast majority of sites are still far above this level.

Furthermore, there is no mention of any measures taken by the authorities to produce such a dramatic drop. The amount of benzene in our air is directly proportional to the amount of petrol consumed. There has been no drop in petrol sales in the past years and vehicles continue to be imported at the rate of 7,000 a year.

The leaded petrol sold locally contains far more benzene than unleaded, so the switch to lead substitute petrol may have accounted for the drop, had it not been introduced at the end of 2002. Catalytic converters would substantially reduce the amount of benzene, however they are not effective over short distances and are apparently removed by car dealers anyway.

The use of alternative modes of transport is non-existent. Public transport remains shunned by the local population. Electric cars and cycle lanes are conspicuous by their absence. Motor scooters remain as heavily taxed as ever.

So where has all the benzene gone? Strangely enough, the levels of other traffic-generated pollutants have not undergone the same magic transformation. Nitrogen dioxide and PM10s are still present in levels far above EU limits.

To make matters worse, the report claims that benzene levels for 2003 are even lower than those of 2002, with no sites exceeding the recommended minimum level. However, this amazing conclusion is reached on the basis of January and February 2003 alone! The author further admits that large chunks of data for previous years are missing or unreliable, the gaps being filled by extrapolation of data.

The report is presented in a spectacular and unscientific manner and is in direct contradiction to previous reports. There is very little support for its conclusions. It gives the impression of having been rushed out as "damage control". If so, it is extremely irresponsible to play down a potential health hazard of such a scale. Tackling it may be a political minefield. That does not mean it can be ignored.