Atmospheric Pollution: Indoor/Outdoor Relationships

In: Health

27 Nov 2014

Indoor/Outdoor Relationships
Although the topic of indoor pollution is considered in a separate article, the extent to which people are actually exposed to pollutants of outdoor origin deserves some comment. Most people in developed countries spend a large proportion of their time indoors, which can be protective. The modern tendency in the interests of fuel economy is toward “tight” buildings that limit the exchange of air between indoors and outdoors. In these circumstances particulates and sulfur dioxide infiltrate only slowly, and the latter is quite rapidly absorbed on furnishings, clothes, and other surfaces so that concentrations fall to a small fraction of those outdoors. Air-conditioning systems may reduce concentrations still further.

These circumstances may not always apply. In the preClean Air Act days in major British cities, the open coal fires in use acted as major ventilators, greatly increasing the flow of air from outside, and homes were necessarily more open, with air passing freely around doors and windows. Although some deposition on surfaces occurred, concentrations usually approached those outdoors and being indoors afforded little protection. Moreover, there was reason to believe that occupants could from time to time be exposed to concentrations of air pollutants (oxides of nitrogen and carbon monoxide, as well as smoke and sulfur dioxide) far higher than those outdoors, being “fumigated” by pollution direct from their own fires when downdrafts occurred, caused by unfavorable wind conditions or merely the opening and shutting of doors. While it has always been difficult to document the effects of these features on the British pollution scene, they may have contributed to the particularly high prevalence of CAD, not only in town dwellers but in the whole community. Reading here

These latter comments link with some current findings in relation to indoor pollution, for increased prevalences of CAD have been reported in parts of China, where coal is used for cooking inside homes with inadequate flues. Similar situations arise in a number of developing countries where coal, wood, or other “biomass” fuels are used for cooking purposes, with exposure occurring either outdoors, directly over the fire, or indoors where flues are poor or nonexistent. Special risks arise for young children accompanying mothers while cooking, and the acute respiratory illnesses that have been reported could have implications for the development of chronic disease. Hence, one of the most severe, if not necessarily the most widespread, risks related to general combustion pollutants concerns exposures in relatively primitive cooking activites, providing scope for preventive measures.


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