Household air pollution from various types of rural kitchens and its exposure assessment

Multinational modelling of PM2.5 and CO exposures from household air pollution in peri-urban Cameroon, Ghana and Kenya

In sub-Saharan Africa, approximately 85% of the population uses polluting cooking fuels (e.g. wood, charcoal). Incomplete combustion of these fuels generates household air pollution (HAP), containing fine particulate matter (PM2.5 ) and carbon monoxide (CO). Due to large spatial variability, increased quantification of HAP levels is needed to improve exposure assessment in sub-Saharan Africa. The CLEAN-Air(Africa) study included 24-h monitoring of PM2.5 and CO kitchen concentrations (npm2.5 = 248/nCO = 207) and female primary cook exposures (npm2.5 = 245/nCO = 222) in peri-urban households in Obuasi (Ghana), Mbalmayo (Cameroon) and Eldoret (Kenya). HAP measurements were combined with survey data on cooking patterns, socioeconomic characteristics and ambient exposure proxies (e.g. walking time to nearest road) in separate PM2.5 and CO mixed-effect log-linear regression models. Model coefficients were applied to a larger study population (n = 937) with only survey data to quantitatively scale up PM2.5 and CO exposures. The final models moderately explained variation in mean 24-h PM2.5 (R2 = 0.40) and CO (R2 = 0.26) kitchen concentration measurements, and PM2.5 (R2 = 0.27) and CO (R2 = 0.14) female cook exposures. Primary/secondary cooking fuel type was the only significant predictor in all four models. Other significant predictors of PM2.5 and CO kitchen concentrations were cooking location and household size; household financial security and rental status were only predictive of PM2.5 concentrations. Cooking location, household financial security and proxies of ambient air pollution exposure were significant predictors of PM2.5 cook exposures. Including objective cooking time measurements (from temperature sensors) from (n = 143) households substantially improved (by 52%) the explained variability of the CO kitchen concentration model, but not the PM2.5 model. Socioeconomic characteristics and markers of ambient air pollution exposure were strongly associated with mean PM2.5 measurements, while cooking environment variables were more predictive of mean CO levels.

Assessment of health risks due to the inhalation of respiratory particulate matter generated in the community kitchens

Exposure to indoor air pollution (IAP) is a potential health hazard leading to premature deaths around the globe. Cooking activity is one of the primary sources of IAP in households. Many studies have focussed on IAP due to cooking practices worldwide, but studies in community kitchens, which serve food for many populations of different age groups, particularly in highly populated developing countries such as India, are non-existent. In this study, the concentrations of particulate matter (PM) of size fractions PM1, PM2.5, and PM10 in indoor air were measured simultaneously and continuously for a duration of up to 20 days in 15 community kitchens using real-time PM monitoring systems (Applied Particle Technology Inc, USA) to assess the associated health risks related to the cooking profession. Three categories of kitchens were studied based on the type of fuel used, viz., LPG, LPG + SBF, and SBF. The concentrations of PM1, PM2.5, and PM10 ranged from 40 to 286 µg m-3, 58 to 418 µg m-3, and 62 to 434 µg m-3, respectively, with corresponding geometric mean (GM) values of 74 µg m-3, 111 µg m-3, and 119 µg m-3. PM ratios were in the order PM2.5/PM10 > PM1/PM2.5 > PM1/PM10. A higher ratio of PM2.5/PM10 was due to the resuspension of particles generated from the cooking process. ELCR values (1.7 × 10-5-1.3 × 10-4) were higher when compared to the recommended limit for humans (1 × 10-6-1 × 10-5) by WHO and US EPA. The HQ values for PM2.5 and PM10 ranged from 1.8 to 13.7 and 0.9 to 4.5, respectively, with corresponding geometric mean (GM) values of 4.7 and 2.2. The ER and AF for all-cause mortality varied between 0.05-0.52 (GM = 0.13) and 0.05-0.34 (GM = 0.11), respectively. The HQ values for all community kitchens > 1, suggesting a high non-carcinogenic risk to the workers. This study revealed that the workers in the community kitchens are exposed to enhanced air pollution. This study has underlined the importance of health issues to the workers attributable to the inhalation of respiratory PM in the community kitchens.

Mitigating household air pollution exposure through kitchen renovation

Globally, over three billion people rely on traditional solid fuels for cooking and heating, leading to significant household air pollution and critical public health concerns. While transitioning to clean energy carriers faces challenges of accessibility and affordability-especially among low-income, rural populations-alternative strategies like kitchen layout modifications and the use of ventilation fans may effectively reduce exposure to pollutants. Here, we analyze factors influencing the adoption of separated kitchens and mechanical ventilation and evaluate changes in human exposure to PM2.5 under different kitchen renovation scenarios by conducting a nationwide survey of household kitchen characteristics in rural China. We found that although 82% of rural households have kitchens separated from other rooms, only 34% use mechanical ventilation. The adoption of ventilation fans is significantly influenced by income and education levels. We estimate that widespread implementation of ventilation fans and separated kitchen designs could prevent approximately 67400 premature deaths annually, resulting in a health benefit of about USD 19 billion per year-substantially exceeding the costs involved. These findings suggest that cost-effective kitchen renovations offer enormous potential for substantial health benefits and present a practical solution compared to the challenges of clean energy transitions in rural areas.

Exploring the cooking energy biomass and its impact on women's health and quality of life in rural households: a micro-environmental study from West Bengal in India

Exposure to household air pollutants has become a significant environmental health concern in developing nations. This study aimed to understand the growing energy consumption within households, particularly for cooking, and its impact on women's health in rural areas. We conducted real-time monitoring of ambient particulate matter (PM2.5) and carbon monoxide (CO) levels in 61 rural kitchens in the Medinipur and Jhargram districts of West Bengal, India. Additionally, we calculated the Standard Living Index (SLI) based on socio-demographic factors from 540 households. Our analyses using ANOVA and chi-square methods revealed significant effects of cooking fuel types and locations on various health indicators among women. Eye irritation was prevalent across all fuel types, followed by shortness of breath (33%), coughing (22%), and dizziness (21%). Alarmingly, nearly half (48%) of children under five consistently accompanied their mothers during cooking, exposing them to health risks. Indoor air pollution, particularly from traditional fuels like fuelwood, cow dung cakes, and leaves, poses a grave threat to families. These fuels emit considerable amounts of PM2.5 and CO, with levels reaching as high as 565 µg/m3 and 12.5 ppm, respectively, leading to respiratory and cardiovascular complications. Clean cooking fuel users, such as those using LPG, reported improved quality of life scores across physical, psychological, social, and environmental categories. This study highlights the urgent need to transition to cleaner cooking fuels to mitigate adverse health effects on women and children in rural households.

Abnormal spirometric patterns and respiratory symptoms in HIV patients with no recent pulmonary infection in a periurban hospital in Ghana

BACKGROUND

Human immunodeficiency virus (HIV) infection is associated with chronic airway obstruction, even in patients who have achieved viral suppression from combination antiretroviral treatment (cART). Spirometry is a supplementary test that aids in diagnosing pulmonary dysfunction in people living with HIV.

AIM

To compare the prevalence of spirometric abnormalities among cART-treated HIV patients and cART-naïve HIV patients with non-HIV controls with no recent history of pulmonary infection in a peri-urban hospital in Ghana.

METHODS

In a case-control design, spirometry was performed in 158 cART-treated HIV patients, 150 cART-naïve HIV patients and 156 non-HIV controls. Clinical, sociodemographic data and respiratory symptoms were collected using a structured questionnaire. Spirometric abnormalities were categorised as obstructive (OSP) or restrictive (RSP) spirometric patterns based on the Cameroonian reference equation.

RESULTS

The prevalence of OSP was higher in the cART-treated and cART-naïve HIV patients compared to non-HIV controls (13.9% vs 10.7% vs 5.1% respectively, p = 0.026), whereas that of RSP was similar among the study groups. Respiratory symptoms were common among cART-treated and cART-naïve HIV patients compared to non-HIV controls (48.1% vs 40% vs 19.2% respectively, p < 0.001). The major factors associated with OSP were female gender [OR (95% CI) = 2.46 (1.09-5.13), p = 0.031], former cigarette smoking [1.92 (1.04-3.89), p < 0.001], exposure to medium-to-high levels of biomass [3.07 (1.16-8.73), p = 0.019], presence of a respiratory symptom [1.89 (1.11-5.08), p = 0.029] and unemployment [3.26 (1.19-8.95), p = 0.042]. The major determinants of RSP were age, female gender [1.74 (1.05-4.29), p = 0.041], former cigarette smoking [2.31 (1.27-6.77), p < 0.001] and medium-to-high biomass exposure [1.58 (1.06-5.37), p = 0.043].

CONCLUSION

In HIV patients without any recent pulmonary infection in a peri-urban area of Ghana, there was a higher prevalence of OSP among cART-treated and cART naïve HIV patients compared to the non-HIV control. However, the prevalence of RSP was similar among HIV patients and non-HIV controls.

Contemporary Concise Review 2023: Environmental and occupational lung diseases

Air pollutants have various effects on human health in environmental and occupational settings. Air pollutants can be a risk factor for incidence, exacerbation/aggravation and death due to various lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), hypersensitivity pneumonitis or pneumonia (HP), pulmonary fibrosis such as pneumoconiosis and malignant respiratory diseases such as lung cancer and malignant pleural mesothelioma. Environmental and occupational respiratory diseases are crucial clinical and social issues worldwide, although the burden of respiratory disease due to environmental and occupational causes varies depending on country/region, demographic variables, geographical location, industrial structure and socioeconomic situation. The correct recognition of environmental and occupational lung diseases and taking appropriate measures are essential to their effective prevention.

Assessing the health consequences of indoor air pollution from biomass fuel combustion on pediatric populations in rural communities of Pakistan

Indoor air pollution arising from burning of biomass fuels poses a significant threat to child health in rural areas of Pakistan. This cross-sectional study aimed to assess health implications associated with indoor air pollution resulting from biomass burning among children under 12 years of age in rural Punjab. A questionnaire-based survey was conducted in six randomly selected rural districts of Punjab, characterized by their primary reliance on biomass fuels. The findings revealed that several characteristics, such as monthly household income, number of living rooms, secondary use of solid fuels, kitchen type, type of cooking stove, and presence of child in the kitchen with their mother, exhibited significant associations (p < 0.05) with negative health impacts among children. Reported health effects among the children included coughing (18.7%), watery eyes (17.7%), eye irritation (12.3%), runny nose (11.8%), breathing difficulties (8.5%), phlegm (38%), headache (25%), nausea (20.1%), dizziness (6.7%), asthma (6.4%), tuberculosis (1.8%), and pneumonia (1.5%).

Personal exposure to household air pollution and lung function in rural Bangladesh: A population-based cross-sectional study

We assessed whether personal exposure to household air pollution [PM2.5 and black carbon (BC)] is associated with lung functions (FEV1, FVC, and their ratio) in non-smoking adults in rural Bangladesh. We measured personal exposure to PM2.5 using gravimetric analysis of PM2.5 mass and BC by reflectance measurement between April 2016 and June 2019. The average 24-hour PM2.5 and BC concentration was 141.0μgm-3 and 13.8μgm-3 for females, and 91.7 μgm-3 and 10.1 μgm-3 for males, respectively. A 1 μgm-3 increase in PM2.5 resulted in a 0.02 ml reduction in FEV1, 0.43 ml reduction in FVC, and 0.004% reduction in FEV1/FVC. We also found a similar inverse relationship between BC and lung functions (9.6 ml decrease in FEV1 and 18.5 ml decrease in FVC per 1μgm-3 increase in BC). A higher proportion of non-smoking biomass fuel users (50.1% of the females and 46.7% of the males) had restrictive patterns of lung function abnormalities, which need further exploration.

Characterising personal, household, and community PM2.5 exposure in one urban and two rural communities in China

BACKGROUND

Cooking and heating in households contribute importantly to air pollution exposure worldwide. However, there is insufficient investigation of measured fine particulate matter (PM2.5) exposure levels, variability, seasonality, and inter-spatial dynamics associated with these behaviours.

METHODS

We undertook parallel measurements of personal, household (kitchen and living room), and community PM2.5 in summer (May-September 2017) and winter (November 2017-Janauary 2018) in 477 participants from one urban and two rural communities in China. After stringent data cleaning, there were 67,326-80,980 person-hours (ntotal = 441; nsummer = 384; nwinter = 364; 307 had repeated PM2.5 data in both seasons) of processed data per microenvironment. Age- and sex-adjusted geometric means of PM2.5 were calculated by key participant characteristics, overall and by season. Spearman correlation coefficients between PM2.5 levels across different microenvironments were computed.

FINDINGS

Overall, 26.4 % reported use of solid fuel for both cooking and heating. Solid fuel users had 92 % higher personal and kitchen 24-h average PM2.5 exposure than clean fuel users. Similarly, they also had a greater increase (83 % vs 26 %) in personal and household PM2.5 from summer to winter, whereas community levels of PM2.5 were 2-4 times higher in winter across different fuel categories. Compared with clean fuel users, solid fuel users had markedly higher weighted annual average PM2.5 exposure at personal (78.2 [95 % CI 71.6-85.3] μg/m3 vs 41.6 [37.3-46.5] μg/m3), kitchen (102.4 [90.4-116.0] μg/m3 vs 52.3 [44.8-61.2] μg/m3) and living room (62.1 [57.3-67.3] μg/m3 vs 41.0 [37.1-45.3] μg/m3) microenvironments. There was a remarkable diurnal variability in PM2.5 exposure among the participants, with 5-min moving average from 10 μg/m3 to 700-1200 μg/m3 across different microenvironments. Personal PM2.5 was moderately correlated with living room (Spearman r: 0.64-0.66) and kitchen (0.52-0.59) levels, but only weakly correlated with community levels, especially in summer (0.15-0.34) and among solid fuel users (0.11-0.31).

CONCLUSION

Solid fuel use for cooking and heating was associated with substantially higher personal and household PM2.5 exposure than clean fuel users. Household PM2.5 appeared a better proxy of personal exposure than community PM2.5.

Kitchen fine particulate matter (PM2.5) concentrations from biomass fuel use in rural households of Northwest Ethiopia

Background

Combustion of solid biomass fuels using traditional stoves which is the daily routine for 3 billion people emits various air pollutants including fine particulate matter which is one of the widely recognized risk factors for various cardiorespiratory and other health problems. But, there is only limited evidences of kitchen PM2.5 concentrations in rural Ethiopia.

Objective

This study is aimed to estimate the 24-h average kitchen area concentrations of PM2.5 and to identify associated factors in rural households of northwest Ethiopia.

Method

The average kitchen area PM2.5 concentrations were measured using a low-cost light-scattering Particle and Temperature Sensor Plus (PATS+) for a 24-h sampling period. Data from the PATS+ was downloaded in electronic form for further analysis. Other characteristics were collected using face-to-face interviews. Independent sample t-test and one-way analysis of variance were used to test differences in PM2.5 concentrations between and among various characteristics, respectively.

Result

Mixed fuels were the most common cooking biomass fuel. The 24-h average kitchen PM2.5 concentrations was estimated to be 405 μg/m3, ranging from 52 to 965 μg/m3. The average concentrations were 639 vs. 336 μg/m3 (p < 0.001) in the thatched and corrugated iron sheet roof kitchens, respectively. The average concentration was also higher among mixed fuel users at 493 vs. 347 μg/m3 (p = 0.042) compared with firewood users and 493 vs. 233 μg/m3 (p = 0.007) as compared with crop residue fuel users. Statistically significant differences were also observed across starter fuel types 613 vs. 343 μg/m3 (p = 0.016) for kerosene vs. dried leaves and Injera baking events 523 vs. 343 μg/m3 (p < 0.001) for baked vs. not baked events.

Conclusion

The average kitchen PM2.5 concentrations in the study area exceeded the world health organization indoor air quality guideline value of 15 μg/m3 which can put pregnant women at greater risk and contribute to poor pregnancy outcomes. Thatched roof kitchen, mixed cooking fuel, kerosene fire starter, and Injera baking events were positively associated with high-level average kitchen PM2.5. concentration. Simple cost-effective interventions like the use of chimney-fitted improved stoves and sensitizing women about factors that aggravate kitchen PM2.5 concentrations could reduce kitchen PM 2.5 levels in the future.

Health risk perceptions of household air pollution and perceived benefits of improved stoves among pregnant women in rural Ethiopia: a mixed method study

OBJECTIVE

Since community perceptions of the risk of biomass smoke and the benefits of improved stoves play a critical role in behaviour change to the uptake and sustainable utilisation of improved stoves, we aimed to assess the level of health risk perception on kitchen smoke and benefits of using improved stoves among pregnant women.

DESIGN

A community-based cross-sectional mixed method study.

SETTING

In six kebeles of a low-income rural community of South Gondar Zone, Northwestern Ethiopia.

PARTICIPANTS

All 455 households with pregnant women aged 18-38 years, in their first-trimester or second-trimester gestation, exclusively use traditional biomass-fuelled or locally modified mud stoves, and the primary cook in her household were included. But completed data were obtained only from 422 households.

RESULT

From 422 completed data, more than half, 63% (95% CI 58% to 68%) had high-level health risk perception of household air pollution, and nearly three-fourths, 74% (95% CI 70% to 79%) of the respondents perceived that using improved stove had benefits for their families. Participants in the 32-38 years age group, rich in asset index, presence of under-five children, being a member of any women group and large family size were positively associated with high-level health risk perception. Whereas respondents in the 18-24 years age group, presence of under-five children, husbands of primary or higher education, high health risk perception and not happy with the current stove were positively associated with perceived benefits of using an improved stove.

CONCLUSION

The observed level of health risk perception of biomass smoke and the benefits of using improved stoves may help to adopt effective intervention measures. This study also suggests that for successful intervention, clean cooking programmes and policies must consider many local factors influencing health risk perception and benefits of using improved stoves.

TRIAL REGISTRATION NUMBER

ACTR202111534227089.

Assessment of indoor air quality of porous media combustion-based cookstoves

The present study analyzes the emission mitigation ability of a porous media combustion (PMC) technology-based cookstove compared to a free flame combustion (FFC) technology-based cookstove. Emission of pollutants, i.e., PM2.5, PM10, and CO, caused due to burning of fuels, namely, methanol, ethanol, kerosene, and LPG in the kitchen environment are measured. The study incorporated exhaustive real-time indoor air quality (IAQ) measurements and presented the temporal variation of measured pollutant concentrations for 2 h (morning meal duration). In addition, 24 h average concentration of the measured pollutants is also compared with the limits prescribed in WHO guidelines for domestic settings. The results emphasized that the utilization of cookstove based on PMC would help in improving the IAQ of the kitchen area by decreasing the concentrations of PM2.5, PM10, and CO. For 2 h duration measurements, the methanol cookstove based on PMC reduced the concentrations of PM2.5, PM10, and CO by 7.7%, 8.1%, and 17.2%, respectively, compared to FFC cookstove. Similarly, in the case of PMC-based LPG cookstove and kerosene cookstove, the respective values were 11.7%, 20.4%, and 41.6% and 55.3%, 62.6%, and 66.6%. Among all the tested cookstoves, PMC-based LPG cookstove achieved the lowest emission values (PM2.5: 20.6 μg/m³, PM10: 31.3 μg/m³, and CO: 1 ppm) which are lower than the prescribed WHO values (PM2.5: 25 μg/m³, PM10: 50 μg/m³, and CO: 6 ppm).

Study on metal elements in indoor particulate matter: a case study of rural residential environment in Northeast China

The use of solid fuels for heating and cooking in rural Northeast China has led to severe indoor metal element pollution in particulate matter (PM), posing a direct threat to human health and creating immense pressure on the sustainability of residential environments. To investigate the levels, sources, and potential health hazards of indoor metal element pollution in this region, we conducted a year-long sampling and monitoring campaign in actual residential settings and used ICP-OES to measure six metal elements (Mn, Cr, Zn, Cu, Pb, and Ni). This study's findings reveal that indoor metal element pollution levels in PM (33,513.65 mg/kg per year) are higher in rural Northeast China compared to other rural areas. Straw burning is the primary source of metal element pollution, followed by motor vehicle emissions and natural soil sources. It is crucial to note that our results indicate a total carcinogenic risk greater than 10^-4 according to the US EPA health risk model assessment, highlighting the high risk posed to human health by indoor metal elements in rural areas. By using a seriously polluted area in Northeast China as a case study, this research provides initial insights into the characteristics and sources of indoor metal pollution in rural areas, offering a reference for future prevention and control of indoor pollution in these regions. Ultimately, this work can help improve the rural habitat and enhance the health of the rural population.

Emission factors and chemical profile of I/SVOCs emitted from household biomass stove in China

Household combustion of biomass straw for cooking or heating is one of the most important emission sources of intermediate volatility and semi-volatile organic compounds (I/SVOCs). However, there are limited studies on the emission factors (EFs) and speciation profiles of I/SVOCs from household stoves burning biomass straw. In this study, experiments were conducted in a typical Chinese stove to test the EFs and species of I/SVOCs in three commonly used straws. It was revealed that EFs of I/SVOCs emitted from the burning of corn straw, rice straw, and wheat straw were 6.7, 1.9, and 9.8 g/kg, respectively, which accounted for 48.3 %, 36.8 %, and 48.6 % of total organic compounds emitted. Particulate organic compounds were dominated by ketones, oxygenated aromatics, acids, esters, and nitrogen-containing compounds, whereas the gaseous phase was dominated by aldehydes, acids, and aromatics. Although I/SVOCs only accounted for 18.1-23.6 % of the gaseous emissions from burning of straw, they represented 64.8-72.9 % of the secondary organic aerosol formation potential (SOAFP). The EFs of 16 priority polycyclic aromatic hydrocarbons (PAHs) were 362.0, 262.5, and 1145.2 mg/kg for corn straw, rice straw, and wheat straw, respectively, among which 3-ring and 4-ring PAHs were the main components. Thus, the results of this study provide new reliable I/SVOCs data that are useful for the development of an accurate emission inventory of organic compounds, simulation of secondary organic aerosol (SOA) formation, and health risk assessment.

Effects of indoor air pollution on tribal community in rural India and health risk assessment due to domestic biomass burning: a realistic approach using the lung deposition model

Indoor air pollution from the combustion of biomass fuel and associated health risks is a critical issue in developing countries. Concentrations of PM2.5 and PM10 are measured in Birbhum, West Bengal, during 2017-2018. PM2.5-bound elemental concentrations of twelve metals are determined in rural kitchens. The results showed higher toxicological risks in BMF (1.15) than the LPG users (0.14). The risk of non-carcinogenic exposure related with dermal contact and ingestion was observed in the acceptable limits (HQ < 1) for all age groups, and the risk associated with inhalation exposure from Cr, Ni, As, and Mn exceeded the acceptable limit. Results also suggest that carcinogenic risks from ingestion and dermal contact are within the acceptable limit (1 × 10-4-1 × 10-6) except Cr and As which were found to exceed the range. The deposition flux (Dφ) for multiple metals in the head airway region, tracheobronchial region, and alveolar regions was found to be higher in teenagers as compared to other groups, whereas the value was lower in infants. Further, it was notified from the Dφ that the metals could pass through the head airways and harm the tracheobronchial tree and alveolar region, increasing the risk of human health.

Assessing the Effects of Stove Use Patterns and Kitchen Chimneys on Indoor Air Quality during a Multiyear Cookstove Randomized Control Trial in Rural India

We conducted indoor air quality (IAQ) measurements during a multiyear cookstove randomized control trial in two rural areas in northern and southern India. A total of 1205 days of kitchen PM_2.5 were measured in control and intervention households during six ∼3 month long measurement periods across two study locations. Stoves used included traditional solid fuel (TSF), improved biomass, and liquefied petroleum gas (LPG) models. Intent-to-treat analysis indicates that the intervention reduced average 24 h PM_2.5 and black carbon in only one of the two follow-up measurement periods in both areas, suggesting mixed effectiveness. Average PM_2.5 levels were ∼50% lower in households with LPG (for exclusive LPG use: >75% lower) than in those without LPG. PM_2.5 was 66% lower in households making exclusive use of an improved chimney stove versus a traditional chimney stove and TSF-exclusive kitchens with a built-in chimney had ∼60% lower PM_2.5 than those without a chimney, indicating that kitchen ventilation can be as important as the stove technology in improving IAQ. Diurnal trends in real-time PM_2.5 indicate that kitchen chimneys were especially effective at reducing peak concentrations, which leads to decreases in daily PM_2.5 in these households. Our data demonstrate a clear hierarchy of IAQ improvement in real world, "stove-stacking" households, driven by different stove technologies and kitchen characteristics.

Preventable mortality attributable to exposure to air pollution at the rural district of Punjab, India

Air pollution has emerged as a leading global health risk in recent decades, where its health impacts are primarily focused on urban areas. In India, semi-urban and rural areas are also emerging as air pollution hotspots. As these regions are out of focus, the current study monitored air pollution (PM_2.5) at a rural district of Punjab in North India and attempted to study the associated health impacts. Hospital data of outpatient department (OPD), inpatient department (IPD) and all-cause mortality was correlated with change in PM_2.5 concentrations. PM_2.5 concentrations showed seasonal variations having relatively higher concentrations during post-monsoon and winter seasons. This rise in air pollution (annual average 92 µg/m³) was found to be mainly due to crop residue burning, including local meteorology. In comparison, hospital data shows that hospital visits and admissions were higher during monsoon. This shows that hospital admissions could not be directly linked to air pollution in rural areas as other factors such as short days during winters and self-medication, socio-economic factors and dependency on local unauthorised traditional healers may influence. The application of the AirQ + model for short-term health effects reveals that out of 2582 total deaths, preventable deaths ranging from 246 (WHO guidelines value - 10 µg/m³) to 159 (Indian NAAQS - 40 µg/m³) could be ascribed to air pollution exposure and specifically PM_2.5. However, these deaths are avoidable by developing strategies to minimise air pollution in rural areas. Hence, a comprehensive approach is needed to plan air pollution reduction strategies, including urban, semi-urban and rural areas.

In-kitchen aerosol exposure in twelve cities across the globe

Poor ventilation and polluting cooking fuels in low-income homes cause high exposure, yet relevant global studies are limited. We assessed exposure to in-kitchen particulate matter (PM_2.5 and PM₁₀) employing similar instrumentation in 60 low-income homes across 12 cities: Dhaka (Bangladesh); Chennai (India); Nanjing (China); Medellín (Colombia); São Paulo (Brazil); Cairo (Egypt); Sulaymaniyah (Iraq); Addis Ababa (Ethiopia); Akure (Nigeria); Blantyre (Malawi); Dar-es-Salaam (Tanzania) and Nairobi (Kenya). Exposure profiles of kitchen occupants showed that fuel, kitchen volume, cooking type and ventilation were the most prominent factors affecting in-kitchen exposure. Different cuisines resulted in varying cooking durations and disproportional exposures. Occupants in Dhaka, Nanjing, Dar-es-Salaam and Nairobi spent > 40% of their cooking time frying (the highest particle emitting cooking activity) compared with ∼ 68% of time spent boiling/stewing in Cairo, Sulaymaniyah and Akure. The highest average PM_2.5 (PM₁₀) concentrations were in Dhaka 185 ± 48 (220 ± 58) μg m^-3 owing to small kitchen volume, extensive frying and prolonged cooking compared with the lowest in Medellín 10 ± 3 (14 ± 2) μg m^-3. Dual ventilation (mechanical and natural) in Chennai, Cairo and Sulaymaniyah reduced average in-kitchen PM_2.5 and PM₁₀ by 2.3- and 1.8-times compared with natural ventilation (open doors) in Addis Ababa, Dar-es-Salam and Nairobi. Using charcoal during cooking (Addis Ababa, Blantyre and Nairobi) increased PM_2.5 levels by 1.3- and 3.1-times compared with using natural gas (Nanjing, Medellin and Cairo) and LPG (Chennai, Sao Paulo and Sulaymaniyah), respectively. Smaller-volume kitchens (<15 m³; Dhaka and Nanjing) increased cooking exposure compared with their larger-volume counterparts (Medellin, Cairo and Sulaymaniyah). Potential exposure doses were highest for Asian, followed by African, Middle-eastern and South American homes. We recommend increased cooking exhaust extraction, cleaner fuels, awareness on improved cooking practices and minimising passive occupancy in kitchens to mitigate harmful cooking emissions.

An appraisal of air quality, thermal comfort, acoustic, and health risk of household kitchens in a developing country

Few studies have documented the air quality, noise, thermal comfort, and health risk assessment of household kitchens related to Sub-Sahara Africa. In this paper, air quality (CO and PM_2.5), thermal comfort (relative humidity (RH) and temperature), noise, and health risk in urban household kitchens with kerosene-fueled stoves were presented. This study was carried out during the dry season (summer) in the Southwestern part of Nigeria. At the breathing zone, PM_2.5 and CO concentrations in the assessed kitchens were measured. In addition, the noise level, RH, and air temperature in the assessed kitchens were also determined. Furthermore, an evaluation of the heat index and health risk of the exposed population to the kerosene-fueled stove kitchens was carried out. During cooking, average CO and PM_2.5 concentrations were 24.77 ± 1.05 ppm and 138.10 ± 2.61 µg/m³, respectively, while the RH was 68.34 ± 0.73%, noise level was 51.14 ± 1.08 dB, and temperature was 29.86 ± 0.23 °C. The CO and noise levels were relatively slightly lower and PM_2.5 was significantly higher than the thresholds recommended by World Health Organisation. In most of the kitchens, the heat index evaluation revealed the possibility of heat exhaustion, heat cramps, and sunstroke with prolonged exposure of the vulnerable group. The air quality index depicted unhealthy (CO exposure) and very unhealthy (PM_2.5 exposure) while the hazard quotient (> 1) implied possible health risk concerning exposure by inhalation. Better design of kitchen with adequate ventilation and improved stoves are suggested.

Visualization and analysis of mapping knowledge domains for the global transition towards clean cooking: a bibliometric review of research output from 1990 to 2020

Current statistics report that 2.6 billion households across the globe rely on polluting and inefficient cooking fuels and technologies, posing death-threatening health risks to people mainly from developing countries/regions. Several studies on clean cooking have been conducted with the emergence of international organizations such as the Clean Cooking Alliance to raise awareness. In the current study, a bibliometric tool, CiteSpace, was employed to analyze the 877 documents retrieved from the SCI-EXPANDED, SSCI, and A&HCI databases on clean cooking research from 1990 to 2020. The results reveal that interest in clean cooking research took a sharp rise in the last decade, especially after 2016. The research field has become increasingly interdisciplinary but has mostly centered on environment, energy, and health. The most productive countries/regions in this field are the USA, India, England, and China. The keyword and citation analyses indicate that research in this field mostly focuses on adverse impacts of household air pollution from unclean cooking fuels and technologies on the environment and public health particularly, in developing countries/regions. Also, the drivers and barriers to the large-scale adoption of clean cooking fuels and technologies have become a topic of interest in recent years. The three most studied clean cooking fuels among various regions are LPG, biogas, and electricity. This study synthesizes global research on clean cooking and may be beneficial to other researchers in understanding current trends in this field and serve as a guide for concentrating on the most important topics.

Subsidized LPG Scheme and the Shift to Cleaner Household Energy Use: Evidence from a Tribal Community of Eastern India

Traditional fuels have both environmental and health impacts. The transition from traditional to clean cooking fuel requires significant public policy actions. The Pradhan Mantri Ujjwala Yojana (PMUY) is one of the primary policies launched in India to eradicate energy poverty among households. Past studies have focused on the drivers that motivate rural households to adopt clean energy and identified the bottlenecks for adoption of clean energy in developing countries. PMUY’s success in terms of scale and pace is critical in the national drive to provide access to clean energy fuel to each citizen. The present study focuses on two objectives. First, we investigate the intensity of adoption and refill of LPG under the PMUY scheme. Second, we use household and other demographic characteristics to examine the factors that influence households’ decision on using LPG as a cooking fuel. Empirical results show that rapid growth has been witnessed in the provision of subsidized LPG connections. However, the annual average refill status stands at two LPG cylinders per beneficiary household indicating that the majority of the beneficiaries have failed to refill their LPG cylinders. This imbalance between rapid enrollment of LPG and limited refill among beneficiary households indicate the continued usage of traditional sources of energy for cooking. From the primary survey conducted in the rural tribal communities of Odisha, we observe that household income and education played a significant role in adoption of LPG and continued usage of LPG gas. Additionally, the logit and ordered probit models identify that membership in self-help groups, accessibility and awareness of LPG are the major adoption drivers. In conclusion, policy makers need to address the challenge of refill status among PMUY consumers. Further, educating households on health benefits through SHG and creating accessibility at village level can actively increase the usage of LPG.

Seasonal variations in carbonaceous species of PM2.5 aerosols at an urban location situated in Indo-Gangetic Plain and its relationship with transport pathways, including the potential sources

The study examines the variation in organic carbon (OC) and elemental carbon (EC) in PM_2.5 concentration at an urban location of Indo-Gangetic Plains (IGP) to understand the impact of seasonality and regional crop residue burning activities. Seasonal cluster analysis of backward air masses and concentration-weighted trajectory (CWT) analysis was performed to identify seasonal transport pathways and potential source regions of carbonaceous aerosols. The mean PM_2.5 level during the study period was 57 ± 41.6 μgm^-3 (5.0-187.3 μgm^-3), whereas OC and EC concentration ranges from 2.8 μgm^-3 to 28.2 μgm^-3 and 1.3 μgm^-3 to 15.5 μgm^-3 with a mean value of 8.4 ± 5.5 μgm^-3 and 5.1 ± 3.3 μgm^-3 respectively. The highest mean PM_2.5 concentration was found during the winter season (111.3 ± 25.5 μgm^-3), which rises 3.6 times compared to the monsoon season. OC and EC also follow a similar trend having the highest levels in winter. Total carbonaceous aerosols contribute ∼38% of PM_2.5 composition. The positive linear trend between OC and EC identified the key sources. HYSPLIT cluster analysis of backward air mass trajectories revealed that during the post-monsoon, winters, pre-monsoon, and monsoon, 71%, 81%, 60%, and 43% of air masses originate within the 500 km radius of IGP. CWT analysis and abundance of OC in post-monsoon and winters season establish a linkage between regional solid-biomass fuel use and crop residue burning activities, including meteorology. Moreover, the low annual average OC/EC ratio (1.75) indicates the overall influence of vehicular emissions. The current dataset of carbonaceous aerosols collated with other Indian studies could be used to validate the global aerosol models on a regional scale and aid in evidence-based air pollution reduction strategies.

Interrelationship of Indoor Particulate Matter and Respiratory Dust Depositions of Women in the Residence of Dhanbad City, India

Women spend relatively more time in indoor environments in developing countries. Exposure to various indoor air pollutants leads them to higher health risks according to household air quality in which they reside. Particulate matter (PM) exposure with their exposure duration inside the household plays a significant role in women's respiratory problems. This study measured size-segregated particulate matter concentrations in 63 residences at different locations. Respiratory dust depositions (RDDs) for 118 women in their different respiratory regions like head airway (HD), tracheobronchial (TB), and alveolar (AL) regions for the three PM size fractions (PM₁₀, PM_2.5, and PM₁) were investigated. For different positions like light exercise and the sitting condition, RDDs values found for AL region were 0.091 μgmin^-1 (SD: 0.067, 0.012-0.408) and 0.028 μgmin^-1 (SD: 0.021, 0.003-0.126) for PM₁₀, 0.325 μgmin^-1 (SD: 0.254, 0.053-1.521) and 0.183 μgmin^-1 (SD: 0.143, 0.031-0.857) for PM_2.5, 0.257 μgmin^-1 (SD: 0.197, 0.043-1.04) and 0.057 μgmin^-1 (SD: 0.044, 0.009-0.233) respectively for PM₁ to females. RDDs values in the AL region significantly increase as PM₁₀ (11%), PM_2.5 (68%), and PM₁ (21%), confirming that for women, the AL region is the most prominent affected zone by fine particles (PM_2.5).

Exposure to long-range transported particulate matter and modeling age-related particle deposition

Exposure to particulate matter (PM) is known to cause cardiovascular disease and increase mortality and morbidity. Asian dust (AD) is a meteorological phenomenon which affects much of East Asia year-round but especially during the spring months. Here, we have characterized concentrations of PM₁₀ and classified synoptic air flow trajectories using HYSPLIT model for Asian dust events (from March to April) in Jeju island, Korea. The ADE is a phenomenon in which sand and dust in the deserts of China or Mongolia rise mainly in spring and are blown away by western winds and gradually subside. The calculated inhaled PM₁₀ doses from specific microenvironments (home, work or school, and transportation) were from 5.28 to 101.48 μg depending on age group and different microenvironments while the calculated PM₁₀ inhaled doses for ADE ranged within 67.92 -769.27 μg. Also, we have evaluated the contribution of specific microenvironments to the exposure for different age groups using time-activity patterns and calculated inhaled PM₁₀ doses and deposited mass/mass flux so as to estimate exposure using multiple-path particle dosimetry (MPPD) model. The monthly average outdoor PM₁₀ concentration range was 29.3-65.4 μg/m³, whereas the monthly PM₁₀ concentration for ADE was 127.0-342.0 μg/m³. Air masses from clusters 1 and 2 were 24% and 29% (in 2017), clusters 2 and 3 were 24% and 32% (in 2018), and clusters 1 and 3 were 28% and 26% (in 2019) for ADE. In the aerosol deposition based on MPPD model, the corresponding values for daily particle deposited mass for two age groups ranged from 8.64 ×10^-5 μg (age 8) to 8.64 ×10^-4 μg (age 21). We assessed the PM_2.5 exposure considering time-activity patterns, age groups, and ADE exposure evaluation caused by long-range transport airflow; this could be helpful for assessing PM₁₀ exposure-related health evaluation.

Influence of agricultural activities on atmospheric pollution during post-monsoon harvesting seasons at a rural location of Indo-Gangetic Plain

The emissions from agricultural activities significantly impact the air quality at local (rural) and regional scales. The study monitored the near real-time concentrations of emission from agrarian activities, i.e., particulate matter (PM₁₀, PM_2.5, PM₁), traces gases and VOCs, along with meteorological parameters in a rural area of Indo-Gangetic Plains (IGP). As different agricultural activities take place simultaneously in the region, sampling period was divided into three phases based on regional agricultural activities as HB (harvesting-burning) period, BTS (burning-tillage-sowing) period and PFS (pesticide-fertilizer spray) period. The highest mean concentration (± standard deviation) of particulate matter, i.e., PM_10, PM_2.5, PM₁ was observed during HB period as 151.0 ± 52.3, 94.7 ± 32.9 and 41.0 ± 16.3 μgm^-3 followed by PFS as 121.7 ± 49.1, 87.8 ± 35.5 and 39.7 ± 15.7 μgm^-3 and BTS period as 92.5 ± 38.8, 63.5 ± 28.4, 26.6 ± 10.9 μgm^-3 respectively. The mean concentration of NO (8.4 ± 3.4 ppb), SO₂ (5.8 ± 1.2 ppb), CO (0.9 ± 0.3 ppm), O₃ (12.5 ± 3.3 ppb) was also highest during harvesting-burning period. In the burning-tillage-sowing period, the mean concentration of NO₂ (31.0 ± 2.9 ppb), benzene (2.8 ± 0.6 μgm^-3) and o-xylene (2.1 ± 0.3 μgm^-3) were highest. The data of crop residue burning fires showed that during HB period, around 34,683 active fires were there in the region (state of Punjab), whereas, in studied district, the number of fire counts were 635. During the HB period, around 70% of the air masses were originated within a 500 km area, whereas during the BTS and PFS period, 75% and 86% of air masses were originated from 500 km region, respectively. The ratio of PM_2.5/PM₁₀ during study period ranged from 0.63 to 0.72 and was observed highest during PFS period. The current study investigated the influence of agricultural activities on air quality during post-monsoon season in a rural area of Indo-Gangetic Plains to understand the impact of these activities on air quality in the region and plan mitigation strategies.

Comparison of Respiratory Health Impacts Associated with Wood and Charcoal Biomass Fuels: A Population-Based Analysis of 475,000 Children from 30 Low- and Middle-Income Countries

BACKGROUND

The World Health Organisation reported that 45% of global acute respiratory infection (ARI) deaths in children under five years are attributable to household air pollution, which has been recognised to be strongly associated with solid biomass fuel usage in domestic settings. The introduction of legislative restrictions for charcoal production or purchase can result in unintended consequences, such as reversion to more polluting biomass fuels such as wood; which may increase health and environmental harms. However, there remains a paucity of evidence concerning the relative health risks between wood and charcoal. This study compares the risk of respiratory symptoms, ARI, and severe ARI among children aged under five years living in wood and charcoal fuel households across 30 low- and middle-income countries.

METHODS

Data from children (N = 475,089) residing in wood or charcoal cooking households were extracted from multiple population-based Demographic and Health Survey databases (DHS) (N = 30 countries). Outcome measures were obtained from a maternal report of respiratory symptoms (cough, shortness of breath and fever) occurring in the two weeks prior to the survey date, generating a composite measure of ARI (cough and shortness of breath) and severe ARI (cough, shortness of breath and fever). Multivariable logistic regression analyses were implemented, with adjustment at individual, household, regional and country level for relevant demographic, social, and health-related confounding factors.

RESULTS

Increased odds ratios of fever (AOR: 1.07; 95% CI: 1.02-1.12) were observed among children living in wood cooking households compared to the use of charcoal. However, no association was observed with shortness of breath (AOR: 1.03; 95% CI: 0.96-1.10), cough (AOR: 0.99; 95% CI: 0.95-1.04), ARI (AOR: 1.03; 95% CI: 0.96-1.11) or severe ARI (AOR: 1.07; 95% CI: 0.99-1.17). Within rural areas, only shortness of breath was observed to be associated with wood cooking (AOR: 1.08; 95% CI: 1.01-1.15). However, an increased odds ratio of ARI was observed in Asian (AOR: 1.25; 95% CI: 1.04-1.51) and East African countries (AOR: 1.11; 95% CI: 1.01-1.22) only.

CONCLUSION

Our population-based observational data indicates that in Asia and East Africa there is a greater risk of ARI among children aged under 5 years living in wood compared to charcoal cooking households. These findings have major implications for understanding the existing health impacts of wood-based biomass fuel usage and may be of relevance to settings where charcoal fuel restrictions are under consideration.

Transition to clean household energy through an application of integrated model: Ensuring sustainability for better health, climate and environment

Sustained use and adoption of clean cooking fuels have become an important concern for developing countries due to the enormous burden of diseases attributable to household air pollution (HAP). The transition and adoption of clean household energy involve various socio-economic, behavioral, and technological barriers at different community levels. Hence, the present paper aims to scrutinize the factors, key determinants, and other interventions among rural households that limit clean cookstoves' sustained uses. The study proposes an integrated model to enhance clean cooking fuel uptake and uses based on the available evidence. The health, climate and environmental factors were identified as the key to trigger the adoption of clean cooking fuel alternatives. The model comprises the integration of components for targeted clean fuel policy interventions and promotes green recovery. The elements include Knowledge, Housing characteristics, Awareness, Interventions, Willingness to pay, Adoption, Lower emissions and Gender Equality (THE KHAIWAL model) to ascertain the intervention focus regions. Integration of model components in policy implementation will promote clean household energy to reduce emissions, leading to improve quality of life, good health, women empowerment, better air quality and climate.

Maternal exposure to cooking smoke and risk of low birth weight in India

Over half of the households in India are using unclean cooking fuels (UCF) and exposed to harmful pollutants that has adverse effects on weight of new born baby. Though studies examined the contextual determinants of birth weight, the association of cooking practices and kitchen location with low birth weight (LBW) is limited in India. This paper investigates the comprehensive effects of household air pollution (HAP) on LBW, mean birth weight (MBW) and birth size in India. Data from 93,721 full-term singleton births from the fourth round of National Family Health Survey, conducted during 2015-16 is used in the analyses. Binary logistic and linear regression methods were used to assess the effect of cooking practices on the outcome variables. Children born in households using clean cooking fuels (CCF) (2877 g, 95% CI: 2876-2877) had 80 g higher birth weight compared with UCF (2797 g, 95% CI: 2796-2798). Households using UCF and cooking without separate kitchen (2779 g, 95% CI:2778-2780) had 59 g and 98 g lower MBW as compared to the households using UCF and cooking in separate kitchen (2817 g, 95% CI:2816-2818) and CCF respectively. Significant associations of LBW observed with the place of cooking and cooking practices but no significant association found for cooking fuels. The HAP from poor cooking practices is associated with risks of LBW in India. Transition from unclean to clean fuels, provision of the separate kitchen should be encouraged to reduce the maternal exposure to HAP and improve birth outcomes.

Impact of COVID-19 lockdown on ambient air quality in megacities of India and implication for air pollution control strategies

The impact of restrictions during various phases of COVID-19 lockdown on daily mean PM2.5 concentration in five Indian megacities (New Delhi, Chennai, Kolkata, Mumbai, and Hyderabad) was studied. The impact was studied for pre-lockdown (1st Mar-24th Mar 2020), lockdown (25th Mar-31st May 2020), and unlocking (1st Jun-31st Aug 2020) phases. The lockdown period comprises 4 lockdown phases with distinct measures, whereas the unlocking period had 3 phases. PM2.5 concentration reduced significantly in all megacities and met the national standards during the lockdown period. The maximum reduction in PM2.5 level was observed in Kolkata (62%), followed by Mumbai (49%), Chennai (34%), and New Delhi (26%) during the lockdown period. Comparatively, Hyderabad exhibited a smaller reduction in PM2.5 concentration, i.e., 10%. The average PM2.5 levels during the lockdown in the peak hour (i.e., 07:00-11:00 h) in New Delhi, Chennai, Kolkata, Mumbai, and Hyderabad decreased by 21.3%, 48.5%, 63.4%, 56.4%, and 23.8%, respectively, compared to those before lockdown period. During the unlocking period, except for Chennai, all megacities showed a reduction in average PM2.5 levels compared to concentrations in the lockdown period, but these reductions were mainly linked with monsoon rains in India. The current study provided an opportunity to study air pollution in the absence of major anthropogenic activities and during limited activities in monsoon season having an ecological design. The study reports a new baseline of PM2.5, except for monsoon, and explores this knowledge to plan future air pollution reduction strategies. The study also discusses how this new learning of knowledge could strengthen air pollution control policies for better air quality and sustainability.Graphical abstract.

Housing Risk Factors Associated with Respiratory Disease: A Systematic Review

Cold, damp and mouldy housing arises from the degradation of the housing stock over time due to weathering and a lack of maintenance. Living in such houses is associated with many adverse impacts on human health, especially for those with existing health issues. This paper presents a systematic review, using the PRISMA protocol, consisting of an exploratory analysis of housing-related risk factors associated with respiratory disease. The review consisted of 360 studies investigating 19 risk factors associated with respiratory conditions. Each fall into one of four categories, namely, (1) outdoor environment-related factors; (2) indoor air pollution-related factors; (3) housing non-structure-related factors; or (4) housing structure-related factors. The results show that effects of poor housing conditions on occupants’ respiratory health is a growing research field, where poor indoor air quality, mainly due to a lack of adequate ventilation, was found to be the most influential risk factor. Usage of solid fuel and living in an urban area without a pollutant-free air filtration system are the main risk factors related to inadequate ventilation. Therefore, an adequate and reliable ventilation system with air-infiltration was considered to be the main mitigation solution to improve indoor air quality. It is suggested that government organisations and health practitioners could use the identified risk factors to measure the healthiness of existing dwellings and take measures to improve existing conditions and develop regulations for new housing construction to promote the healthy home concept. Further research is needed for risk mitigation strategies to reduce the respiratory health burden attributed to housing.

Impact assessment of clean cookstove intervention in Gujarat, India: a potential case for corporate social responsibility (CSR) funding

Exposure to indoor air pollutants released from traditional cookstoves in rural Indian households is a matter of great concern. While there are various studies over several decades focused towards intervention strategies for reducing air pollutants, limited literature exists towards the identification of appropriate methodology for feasible intervention, adoption and usage of improved cookstoves (ICS). In the present study, PM_2.5 and CO microenvironment concentrations are estimated in households using traditional and improved cookstove (NEERDHUR). The reduction in PM_2.5 and CO microenvironment concentrations after the introduction of ICS was found to be 89-94% and 35-57%, respectively. Information-education-communication (IEC) activity was used as a tool to increase the adoption and usage rate in the ICS using households. The cost-benefit analysis was also performed to check the benefits of ICS use, and the benefit-cost ratio was found to be 3 to 4 times. Findings of the study suggest that, although the ICS intervention could significantly improve the indoor air quality, however, it fails to comply with the permissible safe limits; further focus on greener fuels and ventilation characteristics is suggested. The outcomes from the study can help decision-makers, corporate social responsibility fund mobilizers and policymakers for effective policy advocacy to design efforts by promoting clean cooking interventions and linking and mapping these with national missions and flagship programs.

Impact of the COVID-19 pandemic on clean fuel programmes in India and ensuring sustainability for household energy needs

Clean cooking energy strategies are critical for reducing air pollution, improving health, and achieving related Sustainable Development Goals. The recent COVID-19 lockdowns may impact the transition towards clean cooking fuels. The nationwide lockdown is likely to affect key factors such as energy access, income, transportation, etc., that play a role in decisions influencing household fuel use. The rural population already bears the burden of poverty and may not be able to afford and access clean cooking fuels during the lockdown. They are thus vulnerable to reversion to their traditional cooking methods using solid biomass fuels. The household air pollution caused due to the use of polluting fuels increases their susceptibility to non-communicable diseases, and thus may intensify the risk and severity of COVID-19 infection. Hence, there is an urgent need to expand sustainable energy solutions worldwide. The present study applies the DPSIR modeling framework to establish a set of comprehensive indicators for addressing the transition towards clean cooking fuels during the COVID-19 pandemic. The study also provides insights on various strategies adopted in India in response to the COVID-19 pandemic for maintaining continuity of delivering benefits under a clean cookstove program. The study offers future directions to ensure the transition towards cleaner fuels and sustainability.

Exposure levels to PM2.5 and black carbon for people with disabilities in rural homes of Colombia

Indoor exposure to air pollutants emitted by solid fuels used for cooking or heating homes remains as a problem to solve. The most affected people are newborns, mothers, children, and people with disabilities, due to the time they spend at home. This study is the first in a rural area of South America, which measures indoor air pollutants (PM_2.5 and black carbon) in different environments, inhabited by people with disabilities. The research was supported through a sociodemographic characterization, a methodology useful for future studies, continuous monitoring for 72 h of pollutants, and emission sources, cooking habits, and pre-existing diseases were identified. The primary sources of emissions are improved wood-burning stoves and their chimney. In households where firewood is used, the average concentrations of PM_2.5 were the highest (between 10.9 and 3302.5 μg/m³), as were the average concentrations of BC (average 72 h between 2.6 and 51.2 μg/m³) compared with the houses that use gas (average 72 h between 2.6 and 6 μg/m³). In 57% of the households visited, the World Health Organization (WHO) guidelines for PM_2.5 (25 μg/m³ for 24 h) were exceeded. The results reveal that rural concentrations of BC can be up to 2.5 times higher than those of an urban area with high vehicular traffic and high population density and could be used to establish a baseline that allows the implementation of control mechanisms to reduce pollution of indoor air.

Biomass-fuelled improved cookstove intervention to prevent household air pollution in Northwest Ethiopia: a cluster randomized controlled trial

Background

Household air pollution from biomass fuels burning in traditional cookstoves currently appeared as one of the most serious threats to public health with a recent burden estimate of 2.6 million premature deaths every year worldwide, ranking highest among environmental risk factors and one of the major risk factors of any type globally. Improved cookstove interventions have been widely practiced as potential solutions. However, studies on the effect of improved cookstove interventions are limited and heterogeneous which suggested the need for further research.

Methods

A cluster randomized controlled trial study was conducted to assess the effect of biomass-fuelled improved cookstove intervention on the concentration of household air pollution compared with the continuation of an open burning traditional cookstove. A total of 36 clusters were randomly allocated to both arms at a 1:1 ratio, and improved cookstove intervention was delivered to all households allocated into the treatment arm. All households in the included clusters were biomass fuel users and relatively homogenous in terms of basic socio-demographic and cooking-related characteristics. Household air pollution was determined by measuring the concentration of indoor fine particulate, and the effect of the intervention was estimated using the Generalized Estimating Equation.

Results

A total of 2031 household was enrolled in the study across 36 randomly selected clusters in both arms, among which data were obtained from a total of 1977 households for at least one follow-up visit which establishes the intention-to-treat population dataset for analysis. The improved cookstove intervention significantly reduces the concentration of household air pollution by about 343 μg/m³ (Ḃ = − 343, 95% CI − 350, − 336) compared to the traditional cookstove method. The overall reduction was found to be about 46% from the baseline value of 859 (95% CI 837–881) to 465 (95% CI 458–472) in the intervention arm compared to only about 5% reduction from 850 (95% CI 828–872) to 805 (95% CI 794–817) in the control arm.

Conclusions

The biomass-fuelled improved cookstove intervention significantly reduces the concentration of household air pollution compared to the traditional method. This suggests that the implementation of these cookstove technologies may be necessary to achieve household air pollution exposure reductions.

Trial registration

The trial project was retrospectively registered on August 2, 2018, at the clinical trials.gov registry database (https://clinicaltrials.gov/) with the NCT03612362 registration identifier number.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-020-00923-z.

A state-of-the-art review on indoor air pollution and strategies for indoor air pollution control

Indoor air pollution has traditionally received less attention than outdoors pollution despite indoors pollutant levels are typically twice higher, and people spend 80-90% of their life in increasing air-tight buildings. More than 5 million people die every year prematurely from illnesses attributable to poor indoor air quality, which also causes multi-millionaire losses due to reduced employee's productivity, material damages and increased health system expenses. Indoor air pollutants include particulate matter, biological pollutants and over 400 different chemical organic and inorganic compounds, whose concentrations are governed by several outdoor and indoor factors. Prevention of pollutant is not always technically feasible, so the implementation of cost-effective active abatement units is required. Up to date no single physical-chemical technology is capable of coping with all indoor air pollutants in a cost-effective manner. This problem requires the use of sequential technology configurations at the expenses of superior capital and operating costs. In addition, the performance of conventional physical-chemical technologies is still limited by the low concentrations, the diversity and the variability of pollutants in indoor environments. In this context, biotechnologies have emerged as a cost-effective and sustainable platform capable of coping with these limitations based on the biocatalytic action of plants, bacteria, fungi and microalgae. Indeed, biological-based purification systems can improve the energy efficiency of buildings, while providing additional aesthetic and psychological benefits. This review critically assessed the state-of-the-art of the indoor air pollution problem and prevention strategies, along with the recent advances in physical-chemical and biological technologies for indoor pollutants abatement.

Regional and seasonal variations in household and personal exposures to air pollution in one urban and two rural Chinese communities: A pilot study to collect time-resolved data using static and wearable devices

BACKGROUND

Previous studies of the health impact of ambient and household air pollution (AAP/HAP) have chiefly relied on self-reported and/or address-based exposure modelling data. We assessed the feasibility of collecting and integrating detailed personal exposure data in different settings and seasons.

METHODS/DESIGN

We recruited 477 participants (mean age 58 years, 72% women) from three (two rural [Gansu/Henan] and one urban [Suzhou]) study areas in the China Kadoorie Biobank, based on their previously reported fuel use patterns. A time-resolved monitor (PATS+CO) was used to measure continuously for 120-hour the concentration of fine particulate matter (PM2.5) at personal and household (kitchen and living room) levels in warm (May-September 2017) and cool (November 2017-January 2018) seasons, along with questionnaires on participants' characteristics (e.g. socio-demographic, and fuel use) and time-activity (48-hour). Parallel local ambient monitoring of particulate matter (PM1, PM2.5 and PM10) and gaseous pollutants (CO, ozone, nitrogen oxides) was conducted using regularly-calibrated devices. The air pollution exposure data were compared by study sites and seasons.

FINDINGS

Overall 76% reported cooking at least weekly (regular-cooks), and 48% (urban 1%, rural 65%) used solid fuels (wood/coal) for cooking. Winter heating was more common in rural sites than in urban site (74-91% vs 17% daily), and mainly involved solid fuels. Mixed use of clean and solid fuels was common for cooking in rural areas (38%) but not for heating (0%). Overall, the measured mean PM2.5 levels were 2-3 fold higher in the cool than warm season, and in rural (e.g. kitchen: Gansuwarm_season = 142.3 µg/m3; Gansucool_season = 508.1 µg/m3; Henanwarm_season = 77.5 µg/m3; Henancool_season = 222.3 µg/m3) than urban sites (Suzhouwarm_season = 41.6 µg/m3; Suzhoucool_season = 81.6 µg/m3). The levels recorded tended to be the highest in kitchens, followed by personal, living room and outdoor. Time-resolved data show prominent peaks consistently recorded in the kitchen at typical cooking times, and sustained elevated PM2.5 levels (> 100 µg/m3) were observed in rural areas where use of solid fuels for heating was common.

DISCUSSION

Personal air pollution exposure can be readily assessed using a low-cost time-resolved monitor in different settings, which, in combination with other personal and health outcome data, will enable reliable assessment of the long-term health effects of HAP/AAP exposures in general populations.

Exposure assessment of emissions from mobile food carts on New York City streets

Food carts are common along streets in cities throughout the world. In North America, food cart vendors generally use propane, charcoal, or both propane and charcoal (P and C) for food preparation. Although cooking emissions are known to be a major source of indoor air pollution, there is limited knowledge on outdoor cooking's impact on the ambient environment and, in particular, the relative contribution of the different cooking fuels. This field study investigated the air pollution the public is exposed to in the micro-environment around 19 food carts classified into 3 groups: propane, charcoal, and P and C carts. Concentrations near the food carts were measured using both real-time and filter-based methods. Mean real-time concentrations of PM2.5, BC2.5, and particle counts were highest near the charcoal food carts: 196 μg/m3, 5.49 μg/m3, and 69,000 particles/cm3, respectively, with peak exposures of 1520 μg/m3, 67.9 μg/m3, and 235,000 particles/cm3, respectively. In order of pollution emission impacts: charcoal > P and C > propane carts. Thus, significant differences in air pollution emissions occurred in the vicinity of mobile food carts, depending on the fuel used in food preparation. Local air pollution polices should consider these emission factors in regulating food cart vendor operations.

The use of bluetooth low energy Beacon systems to estimate indirect personal exposure to household air pollution

Household air pollution (HAP) generated from solid fuel combustion is a major health risk. Direct measurement of exposure to HAP is burdensome and challenging, particularly for children. In a pilot study of the Household Air Pollution Intervention Network (HAPIN) trial in rural Guatemala, we evaluated an indirect exposure assessment method that employs fixed continuous PM2.5 monitors, Bluetooth signal receivers in multiple microenvironments (kitchen, sleeping area and outdoor patio), and a wearable signal emitter to track an individual's time within those microenvironments. Over a four-month period, we measured microenvironmental locations and reconstructed indirect PM2.5 exposures for women and children during two 24-h periods before and two periods after a liquefied petroleum gas (LPG) stove and fuel intervention delivered to 20 households cooking with woodstoves. Women wore personal PM2.5 monitors to compare direct with indirect exposure measurements. Indirect exposure measurements had high correlation with direct measurements (n = 62, Spearman ρ = 0.83, PM2.5 concentration range: 5-528 µg/m3). Indirect exposure had better agreement with direct exposure measurements (bias: -17 µg/m3) than did kitchen area measurements (bias: -89 µg/m3). Our findings demonstrate that indirect exposure reconstruction is a feasible approach to estimate personal exposure when direct assessment is not possible.

COVID-19 lockdown and its impact on tropospheric NO2 concentrations over India using satellite-based data

The World Health Organization has declared the COVID-19 pandemic a global public health emergency. Many countries of the world, including India, closed their borders and imposed a nationwide lockdown. In India, the lockdown was declared on March 24 for 21 days (March 25-April 14, 2020) and was later extended until May 3, 2020. During the lockdown, all major anthropogenic activities, which contribute to atmospheric pollution (such as industries, vehicles, and businesses), were restricted. The current study examines the impact of the lockdown on tropospheric NO2 concentrations. Satellite-based ozone monitoring instrument sensor data were analyzed in order to investigate the variations in tropospheric NO2 concentrations. The results showed that from March 1 to 21, 2020, the average tropospheric NO2 concentration was 214.4 ×1013 molecule cm-2 over India, and it subsequently decreased by 12.1% over the next four weeks. An increase of 0.8% in tropospheric NO2 concentrations was observed for the same period in 2019 and hence, the reduced tropospheric NO2 concentrations can be attributed to restricted anthropogenic activities during the lockdown. In the absence of significant activities, the contribution of various sources was estimated, and the emissions from biomass burning were identified as a major source of tropospheric NO2 during the lockdown. The findings of this study provide an opportunity to understand the mechanism of tropospheric NO2 emissions over India, in order to improve air quality modeling and management strategies.

Fine Particulate Matter and Gaseous Compounds in Kitchens and Outdoor Air of Different Dwellings

Passive diffusion tubes for volatile organic compounds (VOCs) and carbonyls and low volume particulate matter (PM_2.5) samplers were used simultaneously in kitchens and outdoor air of four dwellings. PM_2.5 filters were analysed for their carbonaceous content (organic and elemental carbon, OC and EC) by a thermo-optical technique and for polycyclic aromatic hydrocarbon (PAHs) and plasticisers by GC-MS. The morphology and chemical composition of selected PM_2.5 samples were characterised by SEM-EDS. The mean indoor PM_2.5 concentrations ranged from 14 µg m⁻³ to 30 µg m⁻³, while the outdoor levels varied from 18 µg m⁻³ to 30 µg m⁻³. Total carbon represented up to 40% of the PM_2.5 mass. In general, the indoor OC/EC ratios were higher than the outdoor values. Indoor-to-outdoor ratios higher than 1 were observed for VOCs, carbonyls and plasticisers. PAH levels were much higher in the outdoor air. The particulate material was mainly composed of soot aggregates, fly ashes and mineral particles. The hazard quotients associated with VOC inhalation suggested a low probability of non-cancer effects, while the cancer risk was found to be low, but not negligible. Residential exposure to PAHs was dominated by benzo[a]pyrene and has shown to pose an insignificant cancer risk.

Indoor air pollution concentrations and cardiometabolic health across four diverse settings in Peru: a cross-sectional study

BACKGROUND

Indoor air pollution is an important risk factor for health in low- and middle-income countries.

METHODS

We 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.

RESULTS

We 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.

CONCLUSIONS

Excessive 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.

Exposure to household air pollution during first 3 years of life and IQ level among 6-8-year-old children in India - A cross-sectional study

Many illnesses have been attributed to the exposure of solid biomass smoke but the effect on intelligence has largely been unexplored. The study aims to examine the effect of exposure to solid biomass smoke during the first 3 years of life on intelligence among 6-8-year-old children. Children aged 6-8 years were enrolled from a primary school and their houses were visited to collect data on socio-economic status and household exposure assessment. Households using LPG as cooking fuel were considered as the unexposed group. All the children were tested for their Intelligence Quotient (IQ) using Malin's Intelligence Scale for Indian Children (MISIC). The mean IQ was calculated as the average of Verbal and Performance score. Potential confounders were adjusted using multivariate general linear model. About 45% of children had average or above-average IQ while the rest had below-average IQ. The mean scores for the arithmetic component of IQ were found to be significantly lower among solid biomass fuel users as compared to LPG users after adjusting for confounders. The mean IQ of LPG users were 5.58 points higher (95% CI: 0.46-10.1) for the arithmetic component as compared to solid biomass users. Children living in the houses using solid biomass fuel for cooking have lower IQ as compared to the children living in the houses using LPG for cooking for arithmetic component even after adjusting for potential confounders.

Kitchen concentrations of fine particulate matter and particle number concentration in households using biomass cookstoves in rural Honduras

Cooking and heating with solid fuels results in high levels of household air pollutants, including particulate matter (PM); however, limited data exist for size fractions smaller than PM2.5 (diameter less than 2.5 μm). We collected 24-h time-resolved measurements of PM2.5 (n = 27) and particle number concentrations (PNC, average diameter 10-700 nm) (n = 44; 24 with paired PM2.5 and PNC) in homes with wood-burning traditional and Justa (i.e., with an engineered combustion chamber and chimney) cookstoves in rural Honduras. The median 24-h PM2.5 concentration (n = 27) was 79 μg/m3 (interquartile range [IQR]: 44-174 μg/m3); traditional (n = 15): 130 μg/m3 (IQR: 48-250 μg/m3); Justa (n = 12): 66 μg/m3 (IQR: 44-97 μg/m3). The median 24-h PNC (n = 44) was 8.5 × 104 particles (pt)/cm3 (IQR: 3.8 × 104-1.8 × 105 pt/cm3); traditional (n = 27): 1.3 × 105 pt/cm3 (IQR: 3.3 × 104-2.0 × 105 pt/cm3); Justa (n = 17): 6.3 × 104 pt/cm3 (IQR: 4.0 × 104-1.2 × 105 pt/cm3). The 24-h average PM2.5 and particle number concentrations were correlated for the full sample of cookstoves (n = 24, Spearman ρ: 0.83); correlations between PM2.5 and PNC were higher in traditional stove kitchens (n = 12, ρ: 0.93) than in Justa stove kitchens (n = 12, ρ: 0.67). The 24-h average concentrations of PM2.5 and PNC were also correlated with the maximum average concentrations during shorter-term averaging windows of one-, five-, 15-, and 60-min, respectively (Spearman ρ: PM2.5 [0.65, 0.85, 0.82, 0.71], PNC [0.74, 0.86, 0.88, 0.86]). Given the moderate correlations observed between 24-h PM2.5 and PNC and between 24-h and the shorter-term averaging windows within size fractions, investigators may need to consider cost-effectiveness and information gained by measuring both size fractions for the study objective. Further evaluations of other stove and fuel combinations are needed.

Seasonal and spatial variability of secondary inorganic aerosols in PM2.5 at Agra: Source apportionment through receptor models

The present study was conducted at sub-urban and rural site of Agra. The main aim of this study was to characterize WSII in terms of spatial, seasonal and formation characteristics and identify the major sources responsible for the pollution of WSII in PM_2.5 particles using different source apportionment models. Since biomass burning is one of the most important sources of PM_2.5 pollution in Agra, a case study was also conducted at rural site to investigate the contribution of biomass burning from cooking activities using different types of fuels. PM_2.5 mass concentrations were higher at sub-urban site (91.0 ± 50.8 μg/m³) than at rural site (77.1 ± 48.6 μg/m³). WSII contributed 50.0% and 45.8% of annual average PM_2.5 mass at both sites. The aerosols were ammonium rich and were therefore alkaline in nature. Aerosol acidity characteristics studied using AIM-II model showed that the aerosols were slightly less acidic at rural site than at sub-urban site. SO₄^2-, NO₃^- and NH₄⁺ were the major contributors of WSII and their formation was favoured mainly in winter. Although, WSII showed slight variations in seasonal and spatial characteristics, the major sources of pollution were found to be similar. Four sources were identified as biomass burning (29.1% and 27.4%), secondary aerosols (26.2% and 22.5%), coal combustion (22.3% and 26.9%) and soil dust (22.4% and 23.1%) at sub-urban and rural sites. The results of case study showed that among different types of biomass fuels cow dung cakes showed maximum PM_2.5 emissions while LPG showed minimum PM_2.5 emissions.

Evaluation of groundwater contamination in Chandigarh: Source identification and health risk assessment

The major objective of the current study is to estimate the groundwater quality and identify the likely sources of contamination in Chandigarh, India. Total 80 groundwater samples were collected from different locations and at various depths. Further, physcio-chemical analysis was done to estimate pH, electrical conductivity (EC), total dissolved solids, total hardness (TH), total alkalinity (TA), Na⁺, K⁺, Cl^-, SO₄^2-, PO₄^3- and NO₃^-. The groundwater samples collected from shallow water sources contain higher concentration of total dissolved salts. EC, TA, Cl^-, TH, Na⁺, and K⁺ were found relatively higher in the shallow aquifer (<150 ft). Based on the location of pollution sources at the surface and consecutive geo-statistical distribution of physicochemical characteristics, this study suggests that non-scientific disposal of municipal solid waste, dumping of industrial waste and agricultural activities, in the nearby areas lead to the deterioration of groundwater of shallow aquifer. These observations were also confirmed using various water quality indices and outcomes of multivariate modeling, including principal component analysis. Health risk assessment for nitrates indicated that 29 groundwater samples pose non-carcinogenic health risk for children due to dermal and oral exposure. Hence, there is a need to establish a system for regularly assessing the groundwater quality to minimize public health risks.

Real-time monitoring of air pollutants in seven cities of North India during crop residue burning and their relationship with meteorology and transboundary movement of air

Air pollutants emissions due to the burning of crop residues could adversely affect human health, environment, and climate. Hence, a multicity campaign was conducted during crop residue burning period in Indo Gangetic Plains (IGP) to study the impact on ambient air quality. Seventeen air pollutants along with five meteorological parameters, were measured using state of the art continuous air quality monitors. The average concentration of PM₁₀, PM_2.5, and PM₁ during the whole campaign were 196.7±30.6, 148.2±20, and 51.2±8.9 μgm^-3 and daily average concentration were found several times higher than national ambient air quality standards for 24h. Amritsar had the highest average concentration of PM_2.5 (178.4±83.8 μgm^-3) followed by Rohtak and Sonipat (158.4±79.8, 156.5±105.3μgm^-3), whereas Chandigarh recorded the lowest concentration (112.3±6.9μgm^-3). The concentration of gaseous pollutants NO, NO₂, NO_x, and SO₂ were also observed highest at Amritsar location, i.e., 6.6±2.6ppb, 6.2±0.7ppb, 12.7±3.0ppb, and 7.5±3.3ppb respectively. The highest average O₃ and CO were 22.5±19.3ppb and 1.5±1.2ppm during the campaign. The level of gaseous pollutants and Volatile organic compounds (VOCs) found to be elevated during the campaign, which can play an important role in the formation of secondary air pollutants. The correlation of meteorology and air pollutants was also studied, and O₃ shows a significant relation with temperature and UV (R=0.87 and 0.74) whereas VOCs shows a significant correlation with temperature (R=-0.21 to -0.47). Air quality data was also analyzed to identify sources of emissions using principal component analysis, and it identifies biomass burning and vehicular activities as major sources of air pollution.

Detection and identification of dust mite allergens in the air conditioning filters in Chandigarh, India

Modern lifestyle with the increasing use of air conditioner (AC) has been linked with breathing difficulties, irritation, dryness, and other symptoms. Hence, dust mites were isolated from AC filters, which causes allergic diseases. A total of 95 dust samples were collected from AC filters from hospitals, guest house, office, school, and homes in Chandigarh, India. The highest concentration of dust mites was detected from hospitals (9/g), offices (7/g), households (6/g), guest houses (3/g), and schools (0/g). Based on the morphology of dust mites observed under a light microscope, Dermatophagoides and Acarus species were found most common. Indoor air quality was also monitored to find out their relation with dust mites present in AC filters. Further, the respiratory health status of indoor facility users was also assessed using a standard questionnaire as a study tool. It was seen that 55.3% of male among the total respondents were having an allergy and only 44.7% of the females had an allergy. The allergy among the male respondents (55.3%) was significantly more (p < 0.05) in comparison with female respondents (44.7%). Some of the respondents also reported a family history of rhinitis (31.9%), asthma (12.8%), recurrent urticaria (6.4%), and conjunctivitis (6.4%). Interestingly, 23.4% of study participants reported that they get disturbed by the use of AC and house dust was found to be the most triggering factor in enhancing the symptoms of allergy. Thus, it is recommended that air conditioner filters should be cleaned regularly to prevent the accumulation of the dust mites and related allergens on filter dust.

Indoor Sources of Air Pollutants

People spend an average of 90% of their time in indoor environments. There is a long list of indoor sources that can contribute to increased pollutant concentrations, some of them related to human activities (e.g. people's movement, cooking, cleaning, smoking), but also to surface chemistry reactions with human skin and building and furniture surfaces. The result of all these emissions is a heterogeneous cocktail of pollutants with varying degrees of toxicity, which makes indoor air quality a complex system. Good characterization of the sources that affect indoor air pollution levels is of major importance for quantifying (and reducing) the associated health risks. This chapter reviews some of the more significant indoor sources that can be found in the most common non-occupational indoor environments.

Levels of trace elements in PM10 collected at roadsides of Addis Ababa, Ethiopia, and exposure risk assessment

Estimation of personal exposure to air pollution is needed to identify high-risk population and to develop mitigation strategies. In this study, an assessment of the potential effects of short-term exposure to PM₁₀ and the elements bound within PM₁₀ was conducted. Samples were obtained from the ten sub-cities of Addis Ababa (three sampling points from each) during the commuting time (traffic congestion and taxi queues). A particle counter consisting of a portable sampling unit with multi-fraction dust samplers was used for sample collection. The elemental composition was analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The mean concentrations of PM₁₀ ranged from 206 to 308 μg m^-3. The highest concentrations of pollutants were found in the major open-market part of the city, Addis Ketema. The lowest concentrations were found at the old-town, Arada sub-cities. The concentration of trace elements (Fe, Cd, As, Cr, Pb, B, Ni, Co, Sn, Cu, and Zn) bound in PM₁₀ ranged from below detectable limit to 0.981 μg m^-3. Regardless of the sampling sub-city, the overall patterns of the mean concentration of elements bound in PM₁₀ were found in the following increasing order of Cr < Cd < As < Co < Ni < Cu < Fe < Pb < Sn < B < Zn < Mn. The results showed that the primary source of Zn, Cr, and Cd may be emissions from on-road vehicles, tire and brake wear. Pb originates mainly from industries and suspended soil dust at the roadside, whereas As, Mn, and B are associated with dust resuspension and biomass and biofuel combustion, respectively. The carcinogenic and non-carcinogenic risks due to chronic exposure to trace elements bound in PM₁₀ at the roadside were assessed in accordance with the U.S. Environmental Protection Agency (US EPA) guidelines. It was determined that Mn, As, and Cd contributed substantially to the inducement of non-carcinogenic health problems to children and adults as a result of exposure while in close proximity to the roadsides.