Household air pollution is a major avoidable risk factor for cardiorespiratory disease

Abstract

Household air pollution (HAP) from biomass fuels, coal, and kerosene burned in open fires, primitive stoves, and lamps causes at least 2 million deaths per year. Many of these deaths occur in children <5 years of age with pneumonia and in women with COPD, lung cancer, and cardiovascular disease. HAP is inextricably linked to poverty, with activities to obtain fuel consuming a large proportion of the time and financial resources of poor households. Thus, fewer resources used in this way means less is available for basic needs like food, education, and health care. The burden of work and the exposure to smoke, particularly during cooking, are predominantly borne by women and children. Although historically HAP has not received sufficient attention from the scientific, medical, public health, development, and policy-making communities, the tide has clearly changed with the broad-based support and launch of the Global Alliance for Clean Cookstoves in 2010. There is now considerable reason for optimism that this substantial cause of cardiorespiratory morbidity and mortality will be addressed comprehensively and definitively. Drawing on our experience from four continents, we provide background information on the problem of HAP, health impacts of HAP, opportunities for research, and the current best solutions.

Figure 1

Typical scenes of women cooking indoors in smoky environments from around the world. A, An Indian woman trying to ignite dried dung in a brick stove releasing a lot of smoke. B, An Ethiopian woman preparing to cook injera over a three-stone fire in a wooden outbuilding. C, A Malawian woman cooking over a three-stone fire in the type of building that would also be used as living and sleeping quarters. D, A Peruvian mother holding a young child while cooking in a smoky kitchen blackened by soot. Particulate matter and carbon monoxide exposures in these settings significantly exceed what are considered safe levels for indoor and occupational environments in developed countries. The individuals shown in the figures gave verbal permission to the authors for publication of the pictures.

Figure 2

Heaps of cattle dung being dried in the sun and ready for burning in household fires. Dung is a popular renewable fuel in settings where animals are kept and in more arid areas where other fuel types are scarce. Combustion of dung generates smoke with particular characteristics, including high levels of endotoxin.

Figure 3

BAL cytospin samples from two Malawian, nonsmoking volunteers who underwent bronchoscopy at the Queen Elizabeth Hospital in Blantyre, viewed under light microscopy. The alveolar macrophages shown contain very different amounts of cytoplasmic particulate matter that likely reflect differences in individual household air pollution and other types of air pollution exposure. A, Minimal inclusions. B, Striking amount of inclusions. The extent of alveolar macrophage particulate loading may be a useful biomarker of biomass smoke exposure. The potential prognostic significance of particular matter burden is currently uncertain.

Figure 4

Exposure response for personal carbon monoxide concentrations in study children for pneumonia from the RESPIRE (Randomized Exposure Study of Pollution Indoors and Respiratory Effects) study. In the RESPIRE trial, personal carbon monoxide exposures were monitored in the study children. A, Carbon monoxide exposures in relation to the risk of physician-diagnosed pneumonia. B, Carbon monoxide exposures in relation to physician-diagnosed severe (hypoxemic) pneumonia. It is likely that substantial reductions in personal exposures to the partial combustion products in biomass smoke will be needed for the full health benefits of clean cookstove interventions to be seen. Reprinted from Smith et al with permission from Elsevier.