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More Diesel - More Allergy

April 30, 2004

An increasing number of new auto buyers choose diesel engines. For asthmatics and those with allergies this is very unfortunate. Particles in diesel exhaust can both worsen and trigger allergic reactions.

"Tough, raw and macho". Such is the advertising for many new off-road vehicles on the market today. They can drive in the mud as well as on pavement and they most often use diesel. It is no longer the "macho boys" that drive these vehicles - now they have also become very popular as family vehicles. The statistics for new autos purchased in February show that almost three out of ten autos that were sold in Norway are fuelled by diesel. In the same period last year, two out of ten autos had diesel engines. But even though the auto industry has successfully made diesel engines cleaner, by among other things installing filters in newer autos, the problem is far from solved. Around 90 percent of heavy traffic in Norway is also fuelled by diesel. And all ships and some trains still have diesel engines.

Great health problem
"The tendency for more to drive diesel engines is risky in a heath perspective," feels Martinus Loevik, unit manager in the Division for environmental immunology at The Norwegian Institute of Public Health. He has led a project financed by The Research Council of Norway, which studies different air pollution particles' significance for asthma and allergy. Loevik observes what makes allergies develop more often and more intensely when mice are exposed to different particles.

They have also participated in a EU project that recently concluded. Here, air samples from different cities in Europe were collected and analysed. The results from both of these projects indicate that diesel exhaust particles are a much larger problem for people with allergies than other particle types that make up air pollution.

Many chemical materials
Diesel exhaust contains approximately one hundred times as many carbon particles as petrol exhaust. The core in the particles is made up of carbon. This core is surrounded by many different chemical materials. The particles from diesel exhaust do not only seem to enhance the symptoms with those who are already allergic, but seem also to trigger latent allergies. "The chemical composition of the particles makes human blood cells generate more antibodies," explains Loevik. In addition it shows that the particle core in itself induces increased allergic immune response with mice.

Research in the USA shows that people with allergies, who are nasally exposed to diesel exhaust particles together with mugwort pollen, showed a much stronger reaction to the pollen than those who were exposed to pollen alone. The same research group has also shown that people to a greater extent develop an allergic reaction to something they were not previously allergic to if they are nasally exposed to diesel exhaust particles together with the new allergen.

"The diesel exhaust particles are very small, less than ten thousandths of a millimetre in diameter. Therefore, they don't settle as easily to the ground, but remain air bound. Flying dust from spiked-tyre driving (during wintertime) and other road dust contain particles that are more coarse and most will be filtered away before they enter human lungs. But when it comes to diesel exhaust particles, the fineness means that up to 30 percent of the mass we inhale can be deposited into the lungs. Therefore, we have to consider pollution from diesel exhaust to be a greater health risk than pavement dust, which we have focused much on in Norway in the last years," explains Loevik.

"The fine particles are health risks for more than people with allergies and asthmatics. Recent studies show that fine particles can also affect acute heart disease," says Loevik.

Research Council of Norway, The