Extreme pollution sensitivity of grasses when SO2 and NO2 are present in the atmosphere together

Abstract

PREDICTIONS of the possible effects of atmospheric pollution on vegetation have usually been based on the results of experiments in which plants were fumigated in the laboratory. For many years it was thought that exposures to SO2 concentrations below 0.30 p.p.m. were not detrimental to higher plants1,2, which led to the belief that this form of pollution is unlikely to cause any appreciable damage to crops in Britain where, even in heavily populated areas, monthly mean SO2 concentrations are usually below 0.15 p.p.m., and daily means rarely exceed 0.30 p.p.m. (ref. 3). Recently, however, evidence has accumulated that concentrations of SO2; below 0.15 p.p.m. can be damaging to plants4–8, casting doubt on the comfortable conclusions drawn from earlier studies. We found that laboratory experiments can underestimate the amount of injury resulting in the field, and report here that combinations of SO2 with NO2 give more realistic effects.