Exposure to air pollution and links with cardiometabolic health in low- and middle-income countries

The aims of this thesis are: 1) to evaluate the performance of low-cost air quality monitors to monitor long-term exposure in rural areas from low- and middle-income countries; 2) to identify the determinants of personal air pollution exposure among women from a semi-rural area in Mozambique; and 3) to evaluate the associations between long-term exposure to ambient air pollution and cardiometabolic health in adults from a peri-urban area in India. We used data from: an experimental study, an observational study, and a cross-sectional epidemiologic study (CHAI). Main results: 1) the performance of low-cost monitors is not reliable yet to replace more expensive research-grade monitors; 2) kerosene-based lighting increased personal air pollution exposure in women from Mozambique; 3) long-term air pollution is associated with elevated blood pressure in women from India; and 4) we found no evidence that long-term air pollution is associated with higher blood glucose levels in peri-urban India.Els objectius d’aquesta tesi són: 1) avaluar el rendiment dels monitors de qualitat de l’aire de baix cost per monitoritzar l’exposició a llarg termini en àrees rurals en països de renda baixa o mitjana; 2) identificar els determinants de l’exposició personal a la contaminació de l’aire en dones d’una àrea semi-rural de Moçambic; i 3) avaluar les associacions a llarg termini entre l’exposició ambiental a la contaminació de l’aire i la salut cardiometabòlica en adults d’una àrea peri-urbana de la Índia. Hem utilitzat dades provinents de: un estudi experimental, un estudi observacional i un estudi epidemiològic transversal (CHAI). Resultats principals: 1) el rendiment de monitors de baix cost encara no és prou fiable per reemplaçar a monitors més cars i establerts en recerca; 2) la il·luminació amb querosè va incrementar l’exposició personal a la contaminació de l‘aire en dones de Moçambic; 3) l’exposició a llarg termini de la contaminació de l’aire està associada a una major pressió arterial en dones de la Índia; i 4) no hem trobat evidència que la exposició a la contaminació de l’aire estigui associada a nivells més alts de glucosa en sang a la Índia peri-urbana

Exposure to air pollution and links with cardiometabolic health in low- and middle-income countries

The aims of this thesis are: 1) to evaluate the performance of low-cost air quality monitors to monitor long-term exposure in rural areas from low- and middle-income countries; 2) to identify the determinants of personal air pollution exposure among women from a semi-rural area in Mozambique; and 3) to evaluate the associations between long-term exposure to ambient air pollution and cardiometabolic health in adults from a peri-urban area in India. We used data from: an experimental study, an observational study, and a cross-sectional epidemiologic study (CHAI). Main results: 1) the performance of low-cost monitors is not reliable yet to replace more expensive research-grade monitors; 2) kerosene-based lighting increased personal air pollution exposure in women from Mozambique; 3) long-term air pollution is associated with elevated blood pressure in women from India; and 4) we found no evidence that long-term air pollution is associated with higher blood glucose levels in peri-urban India.Els objectius d’aquesta tesi són: 1) avaluar el rendiment dels monitors de qualitat de l’aire de baix cost per monitoritzar l’exposició a llarg termini en àrees rurals en països de renda baixa o mitjana; 2) identificar els determinants de l’exposició personal a la contaminació de l’aire en dones d’una àrea semi-rural de Moçambic; i 3) avaluar les associacions a llarg termini entre l’exposició ambiental a la contaminació de l’aire i la salut cardiometabòlica en adults d’una àrea peri-urbana de la Índia. Hem utilitzat dades provinents de: un estudi experimental, un estudi observacional i un estudi epidemiològic transversal (CHAI). Resultats principals: 1) el rendiment de monitors de baix cost encara no és prou fiable per reemplaçar a monitors més cars i establerts en recerca; 2) la il·luminació amb querosè va incrementar l’exposició personal a la contaminació de l‘aire en dones de Moçambic; 3) l’exposició a llarg termini de la contaminació de l’aire està associada a una major pressió arterial en dones de la Índia; i 4) no hem trobat evidència que la exposició a la contaminació de l’aire estigui associada a nivells més alts de glucosa en sang a la Índia peri-urbana

Identifying predictors of personal exposure to air temperature in peri-urban India

Characterizing personal exposure to air temperature is critical to understanding exposure measurement error in epidemiologic studies using fixed-site exposure data and to identify strategies to protect public health. To date, no study evaluating personal air temperature in the general population has been conducted in a low-and-middle income country. We used data from the CHAI study consisting of 50 adults monitored in up to six non-consecutive 24 h sessions in peri-urban south India. We quantified the agreement and association between fixed-site ambient and personal air temperature, and identified predictors of personal air temperature based on housing assessment, self-reported, GPS, remote sensing, and wearable camera data. Mean (SD) daytime (6 am-10 pm) average personal air temperature was 31.2 (2.6) °C and mean nighttime (10 pm-6 am) average temperature was 28.8 (2.8) °C. Agreement between average personal air and fixed-site ambient temperatures was limited, especially at night when personal air temperatures were underestimated by fixed-site temperatures (MBE = -5.6 °C). The proportion of average personal nighttime temperature variability explained by ambient fixed-site temperatures was moderate (R2mar = 0.39); daytime associations were stronger for women (R2mar = 0.51) than for men (R2mar = 0.3). Other predictors of average nighttime personal air temperature included residential altitude, ceiling height, and household income. Predictors of average daytime personal air temperature included roof materials, GPS-tracked altitude, time working in agriculture (for women), and time travelling (for men). No biomass cooking, urban heat island, or greenspace effects were identified. R2mar between ambient fixed-site and personal air temperature indicate that ambient fixed-site temperature is only a moderately useful proxy of personal air temperature in the context of peri-urban India. Our findings suggest that people living in houses at lower altitude, with lower ceiling height and asbestos roofing sheets might be more vulnerable to heat. We also identified households with higher income, women working in agriculture and men with long commutes as disproportionately exposed to high temperatures.This research was funded by the European Research Council under ERC Grant Agreement number 336167 for the CHAI Project. Cathryn Tonne was funded through a Ramón y Cajal fellowship (RYC-2015-17402) awarded by the Spanish Ministry of Economy and Competitiveness. None of the funding sources had a role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication

Performance of low-cost monitors to assess household air pollution [dataset]

Sampling was conducted in a non-smoking private single-family house in the municipality of Terrassa (Spain) during February-March 2016. There are 16 files of .txt format and 7 files of .csv format. The lightest file is 3KB and the heaviest 371KB. Counting all 23 files , there are 2,01MB. Files from the HAPEX device are those which start with “HAPEX”. The following numbers correspond respectively to sensor ID_Day_Month_Year_Hour_Minute_Second of the sampling start. Files from the TZOA-R device are those which start with “TZOA”. The following 4 digits correspond to the sensor ID. Files from the DustTrak device are those which end with “dusttrak”. From 22 Feb to 25 Feb the number of the files’ name corresponds to DayMonthYear (DDMMYY) and HourMinute (HHMM) of the sampling start. In contrast, from 29 Feb, the number of the files’ name corresponds to DayMonthYear (DDMMYYYY) of the sampling start. Files from the EL-USB-CO devices are those which end with “co”. From 22 Feb to 25 Feb the number of the files’ name corresponds to DayMonthYear (DDMMYYYY) of the sampling start plus DayMonthYear (DDMMYYYY) of the sampling end. The numbers before “co” correspond to the sensor ID (e.g. “1co”). In contrast, from 29 Feb, the number of the files’ name corresponds to DayMonthYear (DDMMYYYY) of the sampling start only. File from the Q-Trak device is the one that ends with “qtrak”. The number of the files’ name corresponds to DayMonthYear (DDMMYYYY) of the sampling start. File from BGI concentrations is the one that start with “BGI”. This is a database where the variable corresponding to the PM2.5 concentration is called “PMconcentration” (reported in µg/m3).Raw data of PM2.5 and CO from an indoor wood-combustion experiment. We evaluated the performance of two low-cost sensors measuring fine particulate matter (PM2.5) (HAPEX Nano, Climate Solutions Consulting, and TZOA-R Model RD02, MyTZOA) and one measuring carbon monoxide (CO) (EL-USB-CO, Lascar Electronics Ltd.) in a real-world wood-combustion experiment. PM2.5 devices were compared against a DustTrak (Model 8534, TSI Inc.) and a BGI pump (BGI4004, BGI Inc.) and the EL-USB-CO data-logger was compared against a Q-Trak (Model 7575, TSI Inc.). Sampling was conducted in a single-family house in Terrassa (Spain) during five non-consecutive days. All devices were co-located 1 meter away from an indoor fireplace and 0.6 meters above the ground. Fire was set once per day with hardwood logs and kept burning for 12 hours including a minimum of 2 hours with an opened window. The data provided is the raw output from all the devices tested for the 5 sampling days aiming interested researchers to play with the data and reproduce our findings.The research leading to these results received funding from the Brown India Initiative of Brown University and the European Research Council under ERC Grant Agreement number 336167 for the CHAI Project

Urban-rural differences in hypertension prevalence in low-income and middle-income countries, 1990-2020: A systematic review and meta-analysis

Background: The influence of urbanicity on hypertension prevalence remains poorly understood. We conducted a systematic review and meta-analysis to assess the difference in hypertension prevalence between urban and rural areas in low-income and middle-income countries (LMICs), where the most pronounced urbanisation is underway. Methods and findings: We searched PubMed, Web of Science, Scopus, and Embase, from 01/01/1990 to 10/03/2022. We included population-based studies with ≥400 participants 15 years and older, selected by using a valid sampling technique, from LMICs that reported the urban-rural difference in hypertension prevalence using similar blood pressure measurements. We excluded abstracts, reviews, non-English studies, and those with exclusively self-reported hypertension prevalence. Study selection, quality assessment, and data extraction were performed by 2 independent reviewers following a standardised protocol. Our primary outcome was the urban minus rural prevalence of hypertension. Hypertension was defined as systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure as ≥90 mm Hg and could include use of antihypertensive medication, self-reported diagnosis, or both. We investigated heterogeneity using study-level and socioeconomic country-level indicators. We conducted meta-analysis and meta-regression using random-effects models. This systematic review and meta-analysis has been registered with PROSPERO (CRD42018091671). We included 299 surveys from 66 LMICs, including 19,770,946 participants (mean age 45.4 ± SD = 9 years, 53.0% females and 63.1% from rural areas). The pooled prevalence of hypertension was 30.5% (95% CI, 28.9, 32.0) in urban areas and 27.9% (95% CI, 26.3, 29.6) in rural areas, resulting in a pooled urban-rural difference of 2.45% (95% CI, 1.57, 3.33, I-square: 99.71%, tau-square: 0.00524, Pheterogeneity < 0.001). Hypertension prevalence increased over time and the rate of change was greater in rural compared to urban areas, resulting in a pooled urban-rural difference of 5.75% (95% CI, 4.02, 7.48) in the period 1990 to 2004 and 1.38% (95% CI, 0.40, 2.37) in the period 2005 to 2020, p < 0.001 for time period. We observed substantial heterogeneity in the urban-rural difference of hypertension, which was partially explained by urban-rural definition, probably high risk of bias in sampling, country income status, region, and socioeconomic indicators. The urban-rural difference was 5.67% (95% CI, 4.22, 7.13) in low, 2.74% (95% CI, 1.41, 4.07) in lower-middle and -1.22% (95% CI, -2.73, 0.28) in upper-middle-income countries in the period 1990 to 2020, p < 0.001 for country income. The urban-rural difference was highest for South Asia (7.50%, 95% CI, 5.73, 9.26), followed by sub-Saharan Africa (4.24%, 95% CI, 2.62, 5.86) and reversed for Europe and Central Asia (-6.04%, 95% CI, -9.06, -3.01), in the period 1990 to 2020, p < 0.001 for region. Finally, the urban-rural difference in hypertension prevalence decreased nonlinearly with improvements in Human Development Index and infant mortality rate. Limitations included lack of data available from all LMICs and variability in urban and rural definitions in the literature. Conclusions: The prevalence of hypertension in LMICs increased between 1990 and 2020 in both urban and rural areas, but with a stronger trend in rural areas. The urban minus rural hypertension difference decreased with time, and with country-level socioeconomic development. Focused action, particularly in rural areas, is needed to tackle the burden of hypertension in LMICs

Lack of association between particulate air pollution and blood glucose levels and diabetic status in peri-urban India

Background: Limited evidence exists on the effect of particulate air pollution on blood glucose levels. We evaluated the associations of residential and personal levels of fine particulate matter (PM2.5) and black carbon (BC) with blood glucose and diabetic status among residents of 28 peri-urban villages in South India. Methods: We used cross-sectional data from 5065 adults (≥18 years, 54% men) included in the Andhra Pradesh Children and Parents Study. Fasting plasma glucose was measured once in 2010-2012 and prevalent prediabetes and diabetes were defined following the American Diabetes Association criteria. We estimated annual ambient PM2.5 and BC levels at residence using land-use regression models and annual personal exposure to PM2.5 and BC using prediction models based on direct measurements from a subsample of 402 participants. We used linear and logistic nested mixed-effect models to assess the association between exposure metrics and health outcomes. For personal exposures, we stratified analyses by sex. Results: Mean (SD) residential PM2.5 and BC were 32.9 (2.6) μg/m3 and 2.5 (2.6) μg/m3, respectively; personal exposures to PM2.5 and BC were 54.5 (11.5) μg/m3 and 5.8 (2.5) μg/m3, respectively. Average (SD) fasting blood glucose was 5.3 (1.3) mmol/l, 16% of participants had prediabetes, and 5.5% had diabetes. Residential PM2.5 and BC were not associated with higher blood glucose levels. Personal PM2.5 (20 μg/m3 increase) and BC (1 μg/m3 increase) were negatively associated with blood glucose levels in women (PM2.5: -1.93, 95%CI: -3.12, -0.73; BC: -0.63, 95%CI: -0.90, -0.37). In men, associations were negative for personal PM2.5 (-1.99, 95%CI: -3.56, -0.39) and positive for personal BC (0.49, 95%CI: -0.44, 1.43). We observed no evidence of associations between any exposure and prevalence of prediabetes/diabetes. Conclusions: Our results do not provide evidence that residential exposures to PM2.5 or BC are associated with blood glucose or prevalence of prediabetes/diabetes in this population. Associations with personal exposure may have been affected by unmeasured confounding, highlighting a challenge in using personal exposure estimates in air pollution epidemiology. These associations should be further examined in longitudinal studies.This work was supported by grants 084674/Z from the Wellcome Trust, 336167 from the European Research Council, and RYC-2015-17402 to investigator CT from the Spanish Ministry of Economy and Competitiveness

Ambient particulate air pollution and blood pressure in peri-urban India

BACKGROUND: Evidence linking long-term exposure to particulate air pollution to blood pressure (BP) in high-income countries may not be transportable to low- and middle-income countries. We examined cross-sectional associations between ambient fine particulate matter (PM2.5) and black carbon (BC) with BP (systolic [SBP] and diastolic [DBP]) and prevalent hypertension in adults from 28 peri-urban villages near Hyderabad, India. METHODS: We studied 5531 participants from the Andhra Pradesh Children and Parents Study (18-84 years, 54% men). We measured BP (2010-2012) in the right arm and defined hypertension as SBP ≥130 mmHg and/or DBP ≥80 mmHg. We used land-use regression models to estimate annual average PM2.5 and BC at participant's residence. We applied linear and logistic nested mixed-effect models stratified by sex and adjusted by cooking fuel type to estimate associations between within-village PM2.5 or BC and health. RESULTS: Mean (SD) PM2.5 was 33 µg/m (2.7) and BC was 2.5 µg/m (0.23). In women, a 1 µg/m increase in PM2.5 was associated with 1.4 mmHg higher SBP (95% confidence interval [CI]: 0.12, 2.7), 0.87 mmHg higher DBP (95% CI: -0.18, 1.9), and 4% higher odds of hypertension (95% CI: 0%, 9%). In men, associations with SBP (0.52 mmHg; 95% CI: -0.82, 1.8), DBP (0.41 mmHg; 95% CI: -0.69, 1.5), and hypertension (2% higher odds; 95% CI: -2%, 6%) were weaker. No associations were observed with BC. CONCLUSION: We observed a positive association between ambient PM2.5 and BP and hypertension in women. Longitudinal studies in this region are needed to corroborate our findings

Predictors of personal exposure to black carbon among women in southern semi-rural Mozambique

Sub-Saharan Africa (SSA) has the highest proportion of people using unclean fuels for household energy, which can result in products of incomplete combustion that are damaging for health. Black carbon (BC) is a useful marker of inefficient combustion-related particles; however, ambient air quality data and temporal patterns of personal exposure to BC in SSA are scarce. We measured ambient elemental carbon (EC), comparable to BC, and personal exposure to BC in women of childbearing age from a semi-rural area of southern Mozambique. We measured ambient EC over one year (2014-2015) using a high-volume sampler and an off-line thermo-optical-transmission method. We simultaneously measured 5-min resolved 24-h personal BC using a portable MicroAeth (AE51) in 202 women. We used backwards stepwise linear regression to identify predictors of log-transformed 24-h mean and peak (90th percentile) personal BC exposure. We analyzed data from 187 non-smoking women aged 16-46 years. While daily mean ambient EC reached moderate levels (0.9 μg/m3, Standard Deviation, SD: 0.6 μg/m3), daily mean personal BC reached high levels (15 μg/m3, SD: 19 μg/m3). Daily patterns of personal exposure revealed a peak between 6 and 7 pm (>35 μg/m3), attributable to kerosene-based lighting. Key determinants of mean and peak personal exposure to BC were lighting source, kitchen type, ambient EC levels, and temperature. This study highlights the important contribution of lighting sources to personal exposure to combustion particles in populations that lack access to clean household energy

Predictors of personal exposure to black carbon among women in southern semi-rural Mozambique

Sub-Saharan Africa (SSA) has the highest proportion of people using unclean fuels for household energy, which can result in products of incomplete combustion that are damaging for health. Black carbon (BC) is a useful marker of inefficient combustion-related particles; however, ambient air quality data and temporal patterns of personal exposure to BC in SSA are scarce. We measured ambient elemental carbon (EC), comparable to BC, and personal exposure to BC in women of childbearing age from a semi-rural area of southern Mozambique. We measured ambient EC over one year (2014-2015) using a high-volume sampler and an off-line thermo-optical-transmission method. We simultaneously measured 5-min resolved 24-h personal BC using a portable MicroAeth (AE51) in 202 women. We used backwards stepwise linear regression to identify predictors of log-transformed 24-h mean and peak (90th percentile) personal BC exposure. We analyzed data from 187 non-smoking women aged 16-46 years. While daily mean ambient EC reached moderate levels (0.9 μg/m3, Standard Deviation, SD: 0.6 μg/m3), daily mean personal BC reached high levels (15 μg/m3, SD: 19 μg/m3). Daily patterns of personal exposure revealed a peak between 6 and 7 pm (>35 μg/m3), attributable to kerosene-based lighting. Key determinants of mean and peak personal exposure to BC were lighting source, kitchen type, ambient EC levels, and temperature. This study highlights the important contribution of lighting sources to personal exposure to combustion particles in populations that lack access to clean household energy