Airborne particles are associated with adverse health effects and contribute to excess mortality in epidemiological studies. A recent hypothesis proposes that the high numbers of ultrafine (v0.1 mm diameter) particles in ambient air might provoke alveolar inflammation and subsequently cause exacerbations in pre-existing cardiopulmonary diseases.To test the hypothesis adult asthmatics were followed with daily peak expiratory flow (PEF) measurements and symptom and medication diaries for six months, while simultaneously monitoring particulate pollution in ambient air. The associations between daily health endpoints of 57 asthmatics and indicators of air pollution were examined by multivariate regression models.Daily mean number concentration of particles, but not particle mass (PM10 (particle mass v10 mm), PM2.5 -10, PM2.5, PM1), was negatively associated with daily PEF deviations. The strongest effects were seen for particles in the ultrafine range. However, the effect of ultrafine particles could not definitely be separated from other traffic generated pollutants, namely nitric oxide, nitrogen dioxide and carbon monoxide. No associations were observed with respiratory symptoms or medication use.Particle mass measurements can be strongly influenced by mechanically produced, soil-derived particles, which may not be associated with adverse health effects. Therefore, air quality monitoring should include particle number concentrations, which mainly reflect ultrafine particles.

Fine particulate air pollution, resuspended road dust and respiratory health among symptomatic children. P. Tiittanen, K.L. Timonen, J. Ruuskanen, A. Mirme, J. Pekkanen. #ERS Journals Ltd 1999. ABSTRACT: The short-term association of particulate air pollution with peak expiratory flow rate (PEF) and respiratory symptoms was examined.Forty-nine children with chronic respiratory symptoms aged 8±13 yrs were followed daily for six weeks in spring, 1995, in Kuopio, Finland. Daily concentrations of particulate material with a 50% cut-off aerodynamic diameter #10 mm and #2.5 mm (PM10 and PM2.5, respectively), black carbon, and the number concentrations of particles from 0.01±10 mm diameter were measured. During the study period, PM10 were mainly resuspended soil and street dust, and the concentration was estimated using aluminum content of PM10 samples.No consistent effect of particles was found as the associations varied by lag. Of the lags examined, only 1-day lagged PM2.5 was statistically significantly associated with morning PEF (b=-1.06, SE=0.52 (per interquartile increase in pollutant)). Evening PEF was significantly associated with the 1-day lagged number of particles in the size range 0.1±1.0 mm (b=-1.56, SE=0.72). One-day lagged PM10, PM2.5±10, PM2.5 and resuspended PM10, and 4-day average of PM2.5 were significantly associated with increased risk of cough. Given the short duration of the study, separating the effects of different types of particles was difficult.The present study demonstrates the highly variable size and number distribution and chemical composition of particles in Finland, and underlines the importance of measuring the size and chemical composition of particles to determine which types of particles are associated with health effects. Eur Respir J 1999; 13: 266±273.