Benzene air pollution among worst in Europe

If you thought a walk in the fresh air of the countryside was a healthy way to spend an afternoon, think again. The findings of recent studies show that the quality of air in places we deem pristine, such as Ghajn Tuffieha and Xlendi, is worse than that of urban areas in Sweden.

The studies were conducted by the Environment Protection Department (now part of Malta Environment and Planning Authority) and the university's chemistry department.

The levels of benzene air pollution in Malta are among the worst in Europe, the head of the chemistry department, Alfred Vella, said in an interview.

The results of a number of local studies on benzene, a known cancer-causing agent, and similar pollutants, are grim: urban air in Sweden is actually slightly better than the quality of air in places such as Ghajn Tuffieha, Xlendi and Marsalforn. The quality of air in St Anne Street, Floriana is worse than the "hot spots" of Paris, Prof. Vella said.

"Benzene requires particular attention because of its toxic effects. It is known to be a carcinogen and has been proven to cause bone marrow damage, leukaemia and lymphomas in humans. Petrol is a source of benzene and one of the EU directives limits the amount of benzene in petrol to one per cent," Prof. Vella said.

Studies in the US have shown that exposure to levels of 30 micrograms (µg) of benzene per cubic metre or less for a year increases the risk of contracting cancer by 560 times.

In Sweden, most of the urban background areas have annual mean concentrations of less than 2 µg of benzene per cubic metre and the hot spots do not exceed 14 µg per cubic. Most hot spots are below 10 µg per cubic metre. Hot spots in Paris measure typically 20 to 54 µg per cubic metres during the morning hours.

In Floriana, the comparable values hovered between 60 and 70 µg of benzene per cubic metre. The levels in Sliema ranged between 40 and 74 µg per cubic metres while in San Gwann the levels were around 84 µg.

The lowest annual mean benzene concentrations in 2000 and 2001 were: Marsalforn, 1.88, Xlendi, 2.64 and Ghajn Tuffieha, 2.80 µg.

Prof. Vella said the notion that Malta should have less pollution levels because of the wind action was incorrect as the wind dispersed the pollutants, not eliminated them. The levels of benzene found in the countryside are clearly the result of benzene dispersed from urban areas.

He said the situation was more alarming in Malta because a sizeable bulk of the population is exposed to the hot spot concentrations since residential areas are frequently close or adjacent to busy traffic lanes.

In other countries, air far from major traffic corridors has benzene levels of 1 µg per cubic metre or less, while air pollution in urban or industrial hot spots is about five times that value or even higher.

Prof. Vella said the studies also showed there were very high concentrations of benzene in indoor air in places of entertainment as a result of cigarette smoke.

In one of the experiments, two bars situated in the same street in St Julian's were chosen for investigation. Bar A was equipped with extractor fans while bar B had no similar ventilation and a larger clientele.

The average concentration of benzene measured inside the bars during a typical Saturday night and Sunday morning session were: 18.5 µg per cubic metre in bar A, 726 µg per cubic metre in bar B. Smoke-filled bars in the US have averages of between 3 and 26.9 µg.

Prof. Vella said although the amount of benzene emitted from fuels was far higher than the amounts released by smoking, people tend to live in or spend most of the time in enclosed spaces where elevated levels are reached much more easily.

"It is only in the Sta Venera tunnel that the levels of benzene were as elevated as those found in bar B. Unless one is caught in a traffic jam, one spends less than a minute passing through the tunnel while one spends hours in a smoke-filled bar.

"The alarming levels of benzene in environments similar to those found in bar B present significant health risks for both customers and especially staff and should raise concerns about public health and safety connected with this aspect of the leisure industry.

"Serious consideration should be given to enforcing controls on smoking and to provide adequate ventilation at these places of entertainment in order to protect patrons from an insidious and considerable danger," Prof. Vella said.

Studies at places of work which had smoking and non-smoking areas have shown that the levels of benzene in the air in the non-smoking areas was practically identical, shattering the myth that a smoking corner somewhere creates a safe environment.

"As benzene, and many other harmful chemicals, are odourless, people inhale them without smelling them. Just because you don't smell cigarette smoke, it does not mean you are not inhaling the noxious fumes," Prof. Vella said.

Prof. Vella said benzene and other volatile organic compounds emitted from vehicular exhaust can be considerably reduced by installation of catalytic converters and these devices should be made mandatory. The emission of toxic volatile organic compounds (VOC), including benzene, resulting from the dispensing of petrol is currently uncontrolled and needs to be addressed.

Banning smoking in public places and offices and imposing good ventilation systems at places of entertainment should help to reduce the problem.

"Being a carcinogen, there is probably no really 'safe level' of human exposure to the substance. Different authors come to similar conclusions about estimates of myeloid leukaemia cases increment among populations exposed to benzene vapour," Prof. Vella said.

"The figures we have portray a rather alarming picture of air quality with regards to benzene, which is an extremely noxious compound. Saying that the findings are cause for concern would be an understatement. Seventy-eight per cent of sites monitored exceed the WHO and EU limit value of 5 µg per cubic metre. Many sites are 14 times higher than the WHO and EU limits.

"The quality of air in places of entertainment, where studies have revealed levels which are 145 times higher than WHO and EU limits, are very worrying," Prof. Vella said.

Prof. Vella said the fact that benzene-rich leaded petrol has been phased out should lead to lower atmospheric concentrations of benzene. Installation of fuel vapour recovery systems at petrol stations and in ship to shore transfer, which in Europe have been required by law for several years, would also help mitigate the general VOC problem.

There was no legislation in Malta related to evaporative emissions prior to 2001. Legal Notice 214 of 2001 deals with this matter and service stations with an annual throughput of more than 100 cubic metres of petrol per year will have to control VOC emissions released during storage and fuel transfer. However, this legal notice has not yet been put into effect.

Ship-to-shore petrol transfers remain uncontrolled, despite the considerable impact especially to the locality of Birzebbuga. The findings on the quality of air with respect to benzene suggest that serious consideration should be given for immediate mitigation measures aimed at improving the air quality.

The fitting of catalytic converters to cars has been shown to reduce benzene emissions by up to 90 per cent and EU directives stipulate that three-way catalytic converters had to be installed on all petrol-engine cars as from January 1991.

Prof. Vella said the government should prohibit the importation of petrol-engine vehicles not equipped with catalytic converters.