Abstract
Deprived communities in many cities are exposed to higher levels of outdoor air pollution, and there is increasing evidence of similar disparities for indoor air pollution exposure. There is a need to understand the drivers for this exposure disparity in order to develop effective interventions aimed at improving population health and reducing health inequities. With a focus on London, UK, this paper assembles evidence to examine why indoor exposure to PM2.5, NOx and CO may disproportionately impact low-income groups. In particular, five factors are explored, namely: housing location and ambient outdoor levels of pollution; housing characteristics, including ventilation properties and internal sources of pollution; occupant behaviours; time spent indoors; and underlying health conditions. Evidence is drawn from various sources, including building physics models, modelled outdoor air pollution levels, time–activity surveys, housing stock surveys, geographical data, and peer-reviewed research. A systems framework is then proposed to integrate these factors, highlighting how exposure to high levels of indoor air pollution in low-income homes is in large part due to factors beyond the control of occupants, and is therefore an area of systemic inequality.Policy RelevanceThere is increasing public and political awareness of the impact of air pollution on public health. Strong scientific evidence links exposure to air pollution with morbidity and mortality. Deprived communities may be more affected, however, with limited evidence on how deprivation may influence their personal exposure to air pollution, both outdoors and indoors. This paper describes different factors that may lead to low-income households being exposed to higher levels of indoor air pollution than the general population, using available data and models for London (i.e. living in areas of higher outdoor air pollution, in poor-quality housing, undertaking more pollution-generating activities indoors and spending more time indoors). A systems approach is used to show how these factors lead to systemic exposure inequalities, with low-income households having limited opportunities to improve their indoor air quality. This paper can inform actions and public policies to reduce environmental health inequalities, considering both indoor and outdoor air.
Highlights
Air pollution exposure is the greatest environmental health threat in the UK, with long-term exposures estimated to cause 28,000–36,000 premature deaths a year (COMEAP 2018)
This paper describes different factors that may lead to lowincome households being exposed to higher levels of indoor air pollution than the general population, using available data and models for London
Some studies have found a positive association between outdoor air pollution and deprivation (Samoli et al 2019), while others have suggested this association depends on the city-specific infrastructure (Temam et al 2017)
Summary
Air pollution exposure is the greatest environmental health threat in the UK, with long-term exposures estimated to cause 28,000–36,000 premature deaths a year (COMEAP 2018). The present paper discusses five important reasons why those in low SES groups may on average be exposed to greater levels of indoor air pollution in the domestic environment, focusing on London and the pollutants PM2.5, NOx and CO. To illustrate how these factors may lead to exposure disparities, this paper:. These factors are linked together using a systems analysis to show how systemic inequalities reinforce unequal exposures, with limited opportunities for low-income households to directly improve their own indoor air quality (IAQ)
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