Background: Particulate air pollution has been much discussed in Norway during the last few years. Coarse particles from asphalt are likely to have quite different properties than the far smaller particles from diesel exhaust.
Materials and methods: On the basis of data from the literature and our own research, we discuss the health problem of different types of particles with a focus on allergy and respiratory symptoms.
Results: Diesel exhaust particles have well-documented adverse effects in relation to allergic airway disease. They increase symptoms load in already allergic individuals and also seem to contribute to the increased prevalence of allergy. PM10 is today measured on the basis of weight, not on number. Diesel exhaust particles are much smaller than road surface particles; hence PM10 measurements reflect road surface dust pollution more than exhaust particles.
Interpretation: Focus should now be given to diesel exhaust particles in order to reduce the adverse health effects of particulate air pollution in Norwegian cities.