Household air pollution (HAP) is generated in resource-limited settings where people continue to depend on solid fuels including wood, dung, agricultural crop waste, and coal or kerosene, for their basic energy needs such as cooking and heating. The use of solid fuels results in inefficient combustion, which produce high levels of harmful air pollutants like particulate matter (PM), carbon monoxide (CO), and nitrogen oxides; carcinogenic organic compounds such as benzene, formaldehyde, and 1,3-butadiene; carcinogenic cyclic chemicals such as polycyclic aromatic hydrocarbons (PAHs); and, respiratory irritants such as phenols, cresols, acrolein, and acetaldehyde. Moreover, PM in HAP smoke contains compounds adsorbed to its surface including endotoxin, metals, and microbial components thought to play an important role in PM toxicity.1–3 Thus, HAP is a complex mixture that varies widely in its characteristics.
It is estimated that three billion people worldwide use solid fuels for cooking.4 While the proportion of households that rely on solid fuels for cooking has decreased in the last three decades (62%–33.7% between 1980 and 2016), the absolute number of people exposed to biomass fuel smoke has remained relatively stable due to population growth and rising lifespan.5,6 Countries currently bearing the heaviest disease burdens from exposures to HAP include China, India, Pakistan, Bangladesh, Indonesia, Nigeria, Democratic Republic of Congo, Ethiopia, and Tanzania (Fig. 71-1). The greatest declines in percentages of the population using solid fuels have been documented in Asia, Southern Africa, and South America.5 Despite improvements, the highest burden of exposure occurs in India and China with 560 million and 416 million exposed, respectively.5 There has been little change in the proportion of the population using solid fuels in East, Central, and West sub-Saharan Africa. In particular, in Ethiopia, the Democratic Republic of the Congo, and Tanzania, where almost all of their populations are exposed to HAP.5
Global ranking of risk factors by total number of deaths from all causes for all ages and both sexes in 2016. (Source: Reproduced with Permission From Health Effects Institute. State of Global Air 2018. Special Report. Boston, MA: Health Effects Institute; 2018. https://www.stateofglobalair.org/report.5)
Current regulations for air pollutant concentrations are limited to ambient air quality and do not affect indoor air concentrations in the presence of HAP.7 In an effort to address this concern, the World Health Organization (WHO) developed recommendations for several indoor air pollutants recognizing their importance regarding health impacts related to household fuel combustion.8 Of these pollutants, PM and CO are the most commonly measured for indoor exposure quantification.9,10 Typically, PM in the air covers a range of sizes and its aerodynamic properties determine how deeply it can penetrate and be deposited within the respiratory tract.11 The composition of these particles depends on the combustion process and varies by fuel type, but ...