The German view: Effects of nitrogen dioxide on human health - derivation of health-related short-term and long-term values

The presented overview concerning health relevant effects caused by nitrogen dioxide (NO2) resumes the current state of results from animal experiments and human studies (epidemiology and short-term chambers studies). NO2 concentrations applied in animal experiments were mostly considerably higher than in ambient air. Therefore, short- and long-term limit values were derived from human data. Experimental studies conducted with humans demonstrate effects after short-term exposure to concentrations at: or above 400 mu g NO2/m(3). Effects on patients with light asthma could not be observed after short-term exposure to concentrations below 200 mu g/m(3). On basis of epidemiological long-term studies a threshold below which no effect on human health is expected could not be specified. Two short-term limit values have been proposed to protect public health: a 1-h value of 100 mu g/m(3) and a 24-h mean value of 50 mu g/m(3). Due to the limitations of epidemiological studies to disentangle effects of single pollutants, a longterm limit value cannot be easily derived. However, applying the precautionary principle, it is desirable to adopt an annual mean of 20 mu gNO(2)/m(3) as a long-term mean standard to protect public health. (c) 2005 Elsevier GmbH. All rights reserved.