Pollution by benzene produced by motor traffic is liable to induce leukaemia. However, personal exposure has been shown not to be determined purely by the environmental concentration of benzene in the air of cities, and there are complicating factors.
A study reported in Nature for March 9 involved monitoring benzene pollution in Athens, Antwerp, Murcia, Padua and Rouen, using 50 volunteers who were non-smokers. Some were exposed to traffic fumes and others were indoor workers. A difference in degree of pollution of urban air was detected, increasing with southern patterns of wind direction and speed. This was not paralleled by differences in personal exposure and in benzene measurements made within homes.
With the exception of Athens, population exposure was higher indoors than in the city streets. The hourly benzene concentration oscillated from low during the night to high during the middle of the day and evening, when most people were in the streets. However, average pollution levels at home were 1.51 times those in the streets.
It was concluded that indoor benzene pollution resulted from penetration from the street traffic and subsequent absorption by walls, floors and furnishings. It is significant that northern European towns favour carpets, linoleum and wood surfaces inside rooms, whereas in the warmer south it is more usual to find tiles, marble and bare walls, which do not absorb the pollutants.