Abstract
BackgroundIndoor air pollution is an important risk factor for health in low- and middle-income countries.MethodsWe measured indoor fine particulate matter (PM2.5) and carbon monoxide (CO) concentrations in 617 houses across four settings with varying urbanisation, altitude, and biomass cookstove use in Peru, between 2010 and 2016. We assessed the associations between indoor pollutant concentrations and blood pressure (BP), exhaled carbon monoxide (eCO), C-reactive protein (CRP), and haemoglobin A1c (HbA1c) using multivariable linear regression among all participants and stratifying by use of biomass cookstoves.ResultsWe found high concentrations of indoor PM2.5 across all four settings (geometric mean ± geometric standard deviation of PM2.5 daily average in μg/m3): Lima 41.1 ± 1.3, Tumbes 35.8 ± 1.4, urban Puno 14.1 ± 1.7, and rural Puno 58.8 ± 3.1. High indoor CO concentrations were common in rural households (geometric mean ± geometric standard deviation of CO daily average in ppm): rural Puno 4.9 ± 4.3. Higher indoor PM2.5 was associated with having a higher systolic BP (1.51 mmHg per interquartile range (IQR) increase, 95% CI 0.16 to 2.86), a higher diastolic BP (1.39 mmHg higher DBP per IQR increase, 95% CI 0.52 to 2.25), and a higher eCO (2.05 ppm higher per IQR increase, 95% CI 0.52 to 3.57). When stratifying by biomass cookstove use, our results were consistent with effect measure modification in the association between PM2.5 and eCO: among biomass users eCO was 0.20 ppm higher per IQR increase in PM2.5 (95% CI − 2.05 to 2.46), and among non-biomass users eCO was 5.00 ppm higher per IQR increase in PM2.5 (95% CI 1.58 to 8.41). We did not find associations between indoor air concentrations and CRP or HbA1c outcomes.ConclusionsExcessive indoor concentrations of PM2.5 are widespread in homes across varying levels of urbanisation, altitude, and biomass cookstove use in Peru and are associated with worse BP and higher eCO.
Highlights
Air pollution is a growing threat to public health in lowand middle-income countries (LMICs) [1] and is estimated to be responsible for 4.9 million deaths globally in 2017 [2]
For diastolic blood pressure (DBP), an Interquartile range (IQR) increase in PM2.5 in the adjusted, multi-pollutant model was associated with a higher DBP of 1.42 mmHg, whereas an IQR increase in carbon monoxide (CO) was not associated with DBP (− 0.06 mmHg, 95% CI − 1.48 to 1.35)
While in full models which included Body Mass Index (BMI) and altitude we found no evidence of salt consumption having a substantial impact on any of the examined associations, and alcohol consumption only have an association with blood pressure outcomes, it is likely that BMI, wealth, and altitude are insufficient to fully adjust for all relevant and unmeasured confounders
Summary
Air pollution is a growing threat to public health in lowand middle-income countries (LMICs) [1] and is estimated to be responsible for 4.9 million deaths globally in 2017 [2]. Many people in LMICs spend a majority of their time indoors. In a study in rural Mexico, adult women spent 76% of time indoors [5], while people in urban areas generally spend even more time indoors than rural populations [6]. Exposure-response relationships which rely on estimates of ambient pollutant concentrations [8] are vulnerable to misclassification of true pollutant exposures in populations who spend a majority of time indoors [6]. Indoor air pollution is an important risk factor for health in low- and middle-income countries
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