Health risks associated with environmental pollution, particularly in Eastern Europe, are a cause for concern. In order to gain some insight into the effects of exposure to high levels of air pollution particularly by heavy metals, we measured the concentration of nine plasma proteins in plasma samples from newborn babies and 5- to 6-year old children living in heavily polluted areas of Poland, as well as from some newborns and adults from unpolluted areas of Poland and control samples within the local Southampton population. The concentrations of all proteins measured were in or close to their expected range, with the exception of alpha 1-antitrypsin (alpha 1AT). The concentration of this protein was lower in both groups of Polish children from the polluted areas, particularly in the 5- to 6-year old group. These children were shown to be phenotypically normal. Since adult levels of alpha 1AT are usually reached within 2 weeks postpartum, these findings raise the possibility that continued exposure to high levels of pollution may lead to reduced levels of alpha 1AT in plasma; this may compound the impairment of lung function in children living in highly polluted areas.