The pollution problem in perspective

The effect of the indoor pollutant gases reduced sulphides and organic acids and aldehydes on artefacts in the British Museum collections has been the subject of a long-term study. An evaluation of the data from the study, and experimental work, has shown that alteration by sulphide pollutants is most difficult to prevent; that carbonyl pollutants can be present but not cause alteration of objects; and that five factors influence the alteration of objects. These are the composition and conservation history of the object, the concentration of pollutant gas, the relative humidity and the temperature.