A Narrative Review on the Human Health Effects of Ambient Air Pollution in Sub-Saharan Africa: An Urgent Need for Health Effects Studies

Using deep transfer learning and satellite imagery to estimate urban air quality in data-poor regions

Urban air pollution is a critical public health challenge in low-and-middle-income countries (LMICs). At the same time, LMICs tend to be data-poor, lacking adequate infrastructure to monitor air quality (AQ). As LMICs undergo rapid urbanization, the socio-economic burden of poor AQ will be immense. Here we present a globally scalable two-step deep learning (DL) based approach for AQ estimation in LMIC cities that mitigates the need for extensive AQ infrastructure on the ground. We train a DL model that can map satellite imagery to AQ in high-income countries (HICs) with sufficient ground data, and then adapt the model to learn meaningful AQ estimates in LMIC cities using transfer learning. The trained model can explain up to 54% of the variation in the AQ distribution of the target LMIC city without the need for target labels. The approach is demonstrated for Accra in Ghana, Africa, with AQ patterns learned and adapted from two HIC cities, specifically Los Angeles and New York.

Air Pollution and Racial Disparities in Pregnancy Outcomes in the United States: A Systematic Review

BACKGROUND

Exposure to air pollutants and other environmental factors increases the risk of adverse pregnancy outcomes. There is growing evidence that adverse outcomes related to air pollution disproportionately affect racial and ethnic minorities. The objective of this paper is to explore the importance of race as a risk factor for air pollution-related poor pregnancy outcomes.

METHODS

Studies investigating the effects of exposure to air pollution on pregnancy outcomes by race were reviewed. A manual search was conducted to identify missing studies. Studies that did not compare pregnancy outcomes among two or more racial groups were excluded. Pregnancy outcomes included preterm births, small for gestational age, low birth weight, and stillbirths.

RESULTS

A total of 124 articles explored race and air pollution as risk factors for poor pregnancy outcome. Thirteen percent of these (n=16) specifically compared pregnancy outcomes among two or more racial groups. Findings across all reviewed articles showed more adverse pregnancy outcomes (preterm birth, small for gestational age, low birth weight, and stillbirths) related to exposure to air pollution among Blacks and Hispanics than among non-Hispanic Whites.

CONCLUSION

Evidence support our general understanding of the impact of air pollution on birth outcomes and, specifically, of disparities in exposure to air pollution and birth outcomes for infants born to Black and Hispanic mothers. The factors driving these disparities are multifactorial, mostly social, and economic factors. Reducing or eliminating these disparities require interventions at individual, community, state, and national level.

Significant human health co-benefits of mitigating African emissions

Future African aerosol emissions, and therefore air pollution levels and health outcomes, are uncertain and understudied. Understanding the future health impacts of pollutant emissions from this region is crucial. Here, this research gap is addressed by studying the range in the future health impacts of aerosol emissions from Africa in the Shared Socioeconomic Pathway (SSP) scenarios, using the UK Earth System Model version 1 (UKESM1), along with human health concentration-response functions. The effects of Africa following a high-pollution aerosol pathway are studied relative to a low-pollution control, with experiments varying aerosol emissions from industry and biomass burning. Using present-day demographics, annual deaths within Africa attributable to ambient particulate matter are estimated to be lower by 150 000 (5th-95th confidence interval of 67 000-234 000) under stronger African aerosol mitigation by 2090, while those attributable to O3 are lower by 15 000 (5th-95th confidence interval of 9000-21 000). The particulate matter health benefits are realised predominantly within Africa, with the O3-driven benefits being more widespread - though still concentrated in Africa - due to the longer atmospheric lifetime of O3. These results demonstrate the important health co-benefits from future emission mitigation in Africa.

"It is unbearable to breathe here": air quality, open incineration, and misinformation in Blantyre, Malawi

Blantyre, Malawi's Queen Elizabeth Central Hospital (QECH), or Queen's, as it's known locally, is the country's largest public hospital. However, Queen's is not served by regular municipal waste collection. Rather, most hospital waste (infectious and non-infectious) is gathered by grounds staff and openly burned, in several constantly smouldering piles, sending up clouds of smoke. Speaking directly to an identified knowledge gap on air quality impacts linked to trash burning and the paucity of African urban dwellers' voices on air quality issues, this study employed a mixed-methods approach to both quantitatively measure the air quality around QECH, and to qualitatively investigate the perceived impacts amongst staff and caregivers. Low-cost sensors measuring particulate matter (PM) with particle sizes less than 10 μm (PM10) and less than 2.5 μm (PM2.5), expressed as the mass of PM per volume of air (μg PMx/m3 air) were recorded every 5 min at 8 locations across the QECH for 2 months. Qualitative data collection consisted of 56 interviews with patients, caregivers and hospital staff (including janitorial and maintenance staff, nurses, doctors, and administrators). Our results show that safe air quality thresholds are consistently exceeded across space and time and that the most problematic air quality surrounds the shelter for caregivers and those receiving treatment for HIV/AIDS. Moreover, staff and visitors are severely impacted by the poor air quality within the space, but feel powerless to make changes or address complaints. Waste management interventions are desperately needed lest the patients who arrive at Queen's leave with more health issues than the ones with which they arrived.

A meta-analysis of particulate matter and nitrogen dioxide air quality monitoring associated with the burden of disease in sub-Saharan Africa

Exposure to air pollution is a fundamental obstacle that makes it complex to realize the Sustainable Development Goals (SDGs 3) for good health and wellbeing. It is for this reason that air pollution has been characterized as the global environmental health risk facing the current generation. The risks of air pollution on morbidity, and life expectancy are well documented. This feeds directly to the substantial body of the literature that exists regarding the burden of diseases associated with ambient air pollution. However, the bulk of this literature originates from developed countries. Whilst most of the sub-Saharan African studies extrapolate literature from developed countries to contextualize the risks of elevated air pollution exposure levels associated with the burden of disease. However, extrapolation of epidemiological evidence from developed countries is problematic given that it disregards the social vulnerability. Therefore, given this observation, it is ideal to evaluate if the monitoring executions of hazardous particulate matter and nitrogen dioxide do take into consideration the concerted necessary efforts to associate monitored air pollution exposure levels with the burden of disease. Therefore, based on this background, the current meta-analysis evaluated air quality monitoring associated with the burden of disease across sub-Saharan Africa. To this extent, the current meta-analysis strictly included peer-reviewed published journal articles from the sub-Saharan African regions to gain insight on air quality monitoring associated with the burden of disease. The collected meta-analysis data was captured and subsequently analyzed using Microsoft Excel 2019. This program facilitated the presentation of the meta-analysis data in the form of graphs and numerical techniques. Generally, the results indicate that the sub-Saharan Africa is characterized by a substantial gap in the number of regional studies that evaluate the burden of disease in relation with exposure to air quality.Implications: The work presented here is an original contribution and provides a comprehensive yet succinct overview of the monitoring associated with the burden of disease in sub-Saharan Africa. The author explores if the monitoring executions of hazardous particulate matter and nitrogen dioxide do take into considerations the concerted necessary efforts to associate monitored air pollution exposure levels with the burden of disease. The manuscript includes the most relevant and current literature in a field of study that has not received a deserving degree of research attention in recent years. This is especially true in sub-Saharan Africa, characterized by insufficient monitoring of air quality exposure concentrations.

Sanitary conditions, waste management, safety measures and sources of air pollution associated with shopping malls in Nigeria's largest city

Objectives

Shopping malls are fast becoming one of the most visited public spaces globally. However, information on the possible environmental conditions in relation to health hazards in shopping malls is poorly documented in developing countries. This study assessed the sanitary conditions, waste management, safety measures and sources of air pollution associated with selected shopping malls in Nigeria.Study Design: a descriptive cross-sectional study design was adopted using a comparative approach.

Methods

Three shopping malls (Mall Q, Mall R, and Mall S) in urban areas in Ibadan, Oyo State, Nigeria, were selected using convenience sampling technique. Three major shopping malls were selected using convenience sampling technique. Fifty seven, thirty five, and twenty nine stores were sampled in Mall Q, Mall R, and Mall S respectively. Direct on-site built environment and sanitary conditions of shopping malls were assessed using an observational checklist.

Results

It was observed that all the selected shopping malls had air vents that were free from dust, unbroken walls, and emergency exits, although mold growths were observed on the walls and ceilings of Mall Q and Mall R. Toilet facilities were present and functional across all the shopping malls. Waste management facilities were available across the shopping malls with the absence of overfilled waste bins as regular emptying of the waste bins was a routine. Also, various safety measures and equipment were utilized across all the shopping malls, but safety signals and smoke detectors were absent in Mall R. Furthermore, Mall R and S were 5 m within the proximity of major roads, parking lots and public drainage channels.

Conclusions

These findings reveal a need for improvement in the hygiene and sanitary conditions within shopping malls. Hence, there should be periodic environmental monitoring, and proper housekeeping practices should be encouraged in shopping malls in Nigeria.

High-resolution patterns and inequalities in ambient fine particle mass (PM2.5) and black carbon (BC) in the Greater Accra Metropolis, Ghana

Growing cities in sub-Saharan Africa (SSA) experience high levels of ambient air pollution. However, sparse long-term city-wide air pollution exposure data limits policy mitigation efforts and assessment of the health and climate effects. In the first study of its kind in West Africa, we developed high resolution spatiotemporal land use regression (LUR) models to map fine particulate matter (PM2.5) and black carbon (BC) concentrations in the Greater Accra Metropolitan Area (GAMA), one of the fastest sprawling metropolises in SSA. We conducted a one-year measurement campaign covering 146 sites and combined these data with geospatial and meteorological predictors to develop separate Harmattan and non-Harmattan season PM2.5 and BC models at 100 m resolution. The final models were selected with a forward stepwise procedure and performance was evaluated with 10-fold cross-validation. Model predictions were overlayed with the most recent census data to estimate the population distribution of exposure and socioeconomic inequalities in exposure at the census enumeration area level. The fixed effects components of the models explained 48-69 % and 63-71 % of the variance in PM2.5 and BC concentrations, respectively. Spatial variables related to road traffic and vegetation explained the most variability in the non-Harmattan models, while temporal variables were dominant in the Harmattan models. The entire GAMA population is exposed to PM2.5 levels above the World Health Organization guideline, including even the Interim Target 3 (15 μg/m3), with the highest exposures in poorer neighborhoods. The models can be used to support air pollution mitigation policies, health, and climate impact assessments. The measurement and modelling approach used in this study can be adapted to other African cities to bridge the air pollution data gap in the region.

Meandered and muddled: a systematic review on the impact of air pollution on ocular health

From the years 1970-2023, a systematic overview of the diverse consequences of particulate matter on eye health and a disease classification according to acute, chronic, and genetic are presented using the PubMed, Research Gate, Google Scholar, and Science Direct databases. Various studies on medical aspects correlate with the eye and health. However, from an application perspective, there is limited research on the ocular surface and air pollution. The main objective of the study is to uncover the relationship between eye health and air pollution, particularly particulate matter, along with other external factors acting as aggravators. The secondary goal of the work is to examine the existing models for mimicking human eyes. The study is followed by a questionnaire survey in a workshop, in which the exposure-based investigation was tagged based on their activity. This paper establishes a relationship between particulate matter and its influence on human health, leading to numerous eye diseases like dry eyes, conjunctivitis, myopia, glaucoma, and trachoma. The results of the questionnaire survey indicate that about 68% of the people working in the workshop are symptomatic with tears, blurred vision, and mood swings, while 32% of the people were asymptomatic. Although there are approaches for conducting experiments, the evaluation is not well defined; empirical and numerical solutions for particle deposition on the eye are needed. There prevails a broad gap in the arena of ocular deposition modeling.

The Effects of Trash, Residential Biofuel, and Open Biomass Burning Emissions on Local and Transported PM2.5 and Its Attributed Mortality in Africa

Long-term exposure to ambient fine particulate matter (PM_2.5) is the second leading risk factor of premature death in Sub-Saharan Africa. We use GEOS-Chem to quantify the effects of (a) trash burning, (b) residential solid-fuel burning, and (c) open biomass burning (BB) (i.e., landscape fires) on ambient PM_2.5 and PM_2.5-attributable mortality in Africa. Using a series of sensitivity simulations, we excluded each of the three combustion sources in each of five African regions. We estimate that in 2017 emissions from these three combustion sources within Africa increased global ambient PM_2.5 by 2%, leading to 203,000 (95% confidence interval: 133,000-259,000) premature mortalities yr^-1 globally and 167,000 premature mortalities yr^-1 in Africa. BB contributes more ambient PM_2.5-related premature mortalities per year (63%) than residential solid-fuel burning (29%) and trash burning (8%). Open BB in Central Africa leads to the largest number of PM_2.5-attributed mortalities inside the region, while trash burning in North Africa and residential solid-fuel burning in West Africa contribute the most regional mortalities for each source. Overall, Africa has a unique ambient air pollution profile because natural sources, such as windblown dust and BB, contribute strongly to ambient PM_2.5 levels and PM_2.5-related mortality. Air pollution policies may need to focus on taking preventative measures to avoid exposure to ambient PM_2.5 from these less-controllable sources.

Characterization of fine particulate matter from indoor cooking with solid biomass fuels

Household burning of solid biomass fuels emits pollution particles that are a huge health risk factor, especially in low-income countries (LICs) such as those in Sub-Saharan Africa. In epidemiological studies, indoor exposure is often more challenging to assess than outdoor exposure. Laboratory studies of solid biomass fuels, performed under real-life conditions, are an important path toward improved exposure assessments. Using on- and offline measurement techniques, particulate matter (PM) from the most commonly used solid biomass fuels (charcoal, wood, dung, and crops residue) was characterized in laboratory settings using a way of burning the fuels and an air exchange rate that is representative of real-world settings in low-income countries. All the fuels generated emissions that resulted in concentrations which by far exceed both the annual and the 24-hour-average WHO guidelines for healthy air. Fuels with lower energy density, such as dung, emitted orders of magnitude more than, for example, charcoal. The vast majority of the emitted particles were smaller than 300 nm, indicating high deposition in the alveoli tract. The chemical composition of the indoor pollution changes over time, with organic particle emissions often peaking early in the stove operation. The chemical composition of the emitted PM is different for different biomass fuels, which is important to consider both in toxicological studies and in source apportionment efforts. For example, dung and wood yield higher organic aerosol emissions, and for dung, nitrogen content in the organic PM fraction is higher than for the other fuels. We show that aerosol mass spectrometry can be used to differentiate stove-related emissions from fuel, accelerant, and incense. We argue that further emission studies, targeting, for example, vehicles relevant for LICs and trash burning, coupled with field observations of chemical composition, would advance our understanding of air pollution in LIC. We believe this to be a necessary step for improved air quality policy.

Association between PM2.5 and respiratory hospitalization in Rio Branco, Brazil: Demonstrating the potential of low-cost air quality sensor for epidemiologic research

BACKGROUND

There is currently a scarcity of air pollution epidemiologic data from low- and middle-income countries (LMICs) due to the lack of air quality monitoring in these countries. Additionally, there is limited capacity to assess the health effects of wildfire smoke events in wildfire-prone regions like Brazil's Amazon Basin. Emerging low-cost air quality sensors may have the potential to address these gaps.

OBJECTIVES

We investigated the potential of PurpleAir PM2.5 sensors for conducting air pollution epidemiologic research leveraging the United States Environmental Protection Agency's United States-wide correction formula for ambient PM_2.5.

METHODS

We obtained raw (uncorrected) PM_2.5 concentration and humidity data from a PurpleAir sensor in Rio Branco, Brazil, between 2018 and 2019. Humidity measurements from the PurpleAir sensor were used to correct the PM_2.5 concentrations. We established the relationship between ambient PM_2.5 (corrected and uncorrected) and daily all-cause respiratory hospitalization in Rio Branco, Brazil, using generalized additive models (GAM) and distributed lag non-linear models (DLNM). We used linear regression to assess the relationship between daily PM_2.5 concentrations and wildfire reports in Rio Branco during the wildfire seasons of 2018 and 2019.

RESULTS

We observed increases in daily respiratory hospitalizations of 5.4% (95%CI: 0.8%, 10.1%) for a 2-day lag and 5.8% (1.5%, 10.2%) for 3-day lag, per 10 μg/m³ PM_2.5 (corrected values). The effect estimates were attenuated when the uncorrected PM_2.5 data was used. The number of reported wildfires explained 10% of daily PM2.5 concentrations during the wildfire season.

DISCUSSION

Exposure-response relationships estimated using corrected low-cost air quality sensor data were comparable with relationships estimated using a validated air quality modeling approach. This suggests that correcting low-cost PM_2.5 sensor data may mitigate bias attenuation in air pollution epidemiologic studies. Low-cost sensor PM_2.5 data could also predict the air quality impacts of wildfires in Brazil's Amazon Basin.

Information entropy tradeoffs for efficient uncertainty reduction in estimates of air pollution mortality

Implementing effective policy to protect human health from the adverse effects of air pollution, such as premature mortality, requires reducing the uncertainty in health outcomes models. Here we present a novel method to reduce mortality uncertainty by increasing the amount of input data of air pollution and health outcomes, and then quantifying tradeoffs associated with the different data gained. We first present a study of long-term mortality from fine particulate matter (PM_2.5) based on simulated data, followed by a real-world application of short-term PM_2.5-related mortality in an urban area. We employ information yield curves to identify which variables more effectively reduce mortality uncertainty when increasing information. Our methodology can be used to explore how specific pollution scenarios will impact mortality and thus improve decision-making. The proposed framework is general and can be applied to any real case-scenario where knowledge in pollution, demographics, or health outcomes can be augmented through data acquisition or model improvements to generate more robust risk assessments.

Environmental Pollutants and Oxidative Stress in Terrestrial and Aquatic Organisms: Examination of the Total Picture and Implications for Human Health

There is current great international concern about the contribution of environmental pollution to the global burden of disease particularly in the developing, low- and medium-income countries. Industrial activities, urbanization, developmental projects as well as various increased anthropogenic activities involving the improper generation, management and disposal of pollutants have rendered today’s environment highly polluted with various pollutants. These pollutants include toxic metals (lead, cadmium, mercury, arsenic), polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pesticides and diesel exhaust particles most of which appear to be ubiquitous as well as have long-term environmental persistence with a wide range of toxicities such as oxidative stress among others. Oxidative stress, which may arise from increased production of damaging free radicals emanating from increased pollutant burden and depressed bioavailability of antioxidant defenses causes altered biochemical and physiological mechanisms and has been implicated in all known human pathologies most of which are chronic. Oxidative stress also affects both flora and fauna and plants are very important components of the terrestrial environment and significant contributors of nutrients for both man and animals. It is also remarkable that the aquatic environment in which sea animals and creatures are resident is also highly polluted, leading to aquatic stress that may affect the survival of the aquatic animals, sharing in the oxidative stress. These altered terrestrial and aquatic environments have an overarching effect on human health. Antioxidants neutralize the damaging free radicals thus, they play important protective roles in the onset, progression and severity of the unmitigated generation of pollutants that ultimately manifest as oxidative stress. Consequently, human health as well as that of aquatic and terrestrial organisms may be protected from environmental pollution by mitigating oxidative stress and employing the principles of nutritional medicine, essentially based on antioxidants derived mainly from plants, which serve as the panacea of the vicious state of environmental pollutants consequently, the health of the population. Understanding the total picture of oxidative stress and integrating the terrestrial and aquatic effects of environmental pollutants are central to sustainable health of the population and appear to require multi-sectoral collaborations from diverse disciplinary perspectives; basically the environmental, agricultural and health sectors.

Ambient and indoor air pollution exposure and adverse birth outcomes in Adama, Ethiopia

Air pollution poses a threat to human health, with pregnant women and their developing fetuses being particularly vulnerable. A high dual burden of ambient and indoor air pollution exposure has been identified in Ethiopia, but studies investigating their effects on adverse birth outcomes are currently lacking. This study explores the association between ambient air pollution (NO_X and NO₂) and indoor air pollution (cooking fuel type) and fetal and neonatal death in Adama, Ethiopia. A prospective cohort of mothers and their babies was used, into which pregnant women were recruited at their first antenatal visit (n = 2085) from November 2015 to February 2018. Previously developed land-use regression models were utilized to assess ambient concentrations of NO_X and NO₂ at the residential address, whereas data on cooking fuel type was derived from questionnaires. Birth outcome data was obtained from self-reported questionnaire responses during the participant's postnatal visit or by phone if an in-person meeting was not possible. Binary logistic regression was employed to assess associations within the final study population (n = 1616) using both univariate and multivariate models; the latter of which adjusted for age, education, parity, and HIV status. Odds ratios (OR) and their corresponding 95% confidence intervals (CI) were reported. Within the cohort, 69 instances of fetal death (n = 16 miscarriages; n = 53 stillbirths) and 16 cases of neonatal death were identified. The findings suggest a tendency towards an association between ambient NO_X and NO₂ exposure during pregnancy and an increased risk of fetal death overall as well as stillbirth, specifically. However, statistical significance was not observed. Results for indoor air pollution and neonatal death were inconclusive. As limited evidence on the effects of exposure to ambient air pollution on adverse birth outcomes exists in Sub-Saharan Africa and Ethiopia, additional studies with larger study populations should be conducted.

Ambient air pollution and non-communicable respiratory illness in sub-Saharan Africa: a systematic review of the literature

INTRODUCTION

Aerosol pollutants are known to raise the risk of development of non-communicable respiratory diseases (NCRDs) such as asthma, chronic bronchitis, chronic obstructive pulmonary disease, and allergic rhinitis. Sub-Saharan Africa's rapid pace of urbanization, economic expansion, and population growth raise concerns of increasing incidence of NCRDs. This research characterizes the state of research on pollution and NCRDs in the 46 countries of Sub-Saharan Africa (SSA). This research systematically reviewed the literature on studies of asthma; chronic bronchitis; allergic rhinitis; and air pollutants such as particulate matter, ozone, NOx, and sulfuric oxide.

METHODS

We searched three major databases (PubMed, Web of Science, and Scopus) using the key words "asthma", "chronic bronchitis", "allergic rhinitis", and "COPD" with "carbon monoxide (CO)", "sulfuric oxide (SO)", "ozone (O3)", "nitrogen dioxide (NO2)", and "particulate matter (PM)", restricting the search to the 46 countries that comprise SSA. Only papers published in scholarly journals with a defined health outcome in individuals and which tested associations with explicitly measured or modelled air exposures were considered for inclusion. All candidate papers were entered into a database for review.

RESULTS

We found a total of 362 unique research papers in the initial search of the three databases. Among these, 14 met the inclusion criteria. These papers comprised studies from just five countries. Nine papers were from South Africa; two from Malawi; and one each from Ghana, Namibia, and Nigeria. Most studies were cross-sectional. Exposures to ambient air pollutants were measured using spectrometry and chromatography. Some studies created composite measures of air pollution using a range of data layers. NCRD outcomes were measured by self-reported health status and measures of lung function (spirometry). Populations of interest were primarily schoolchildren, though a few studies focused on secondary school students and adults.

CONCLUSIONS

The paucity of research on NCRDs and ambient air pollutant exposures is pronounced within the African continent. While capacity to measure air quality in SSA is high, studies targeting NCRDs should work to draw attention to questions of outdoor air pollution and health. As the climate changes and SSA economies expand and countries urbanize, these questions will become increasingly important.

Short-Term Joint Effects of PM10, NO2 and SO2 on Cardio-Respiratory Disease Hospital Admissions in Cape Town, South Africa

Background/Aim: In sub-Sahara Africa, few studies have investigated the short-term association between hospital admissions and ambient air pollution. Therefore, this study explored the association between multiple air pollutants and hospital admissions in Cape Town, South Africa. Methods: Generalized additive quasi-Poisson models were used within a distributed lag linear modelling framework to estimate the cumulative effects of PM₁₀, NO₂, and SO₂ up to a lag of 21 days. We further conducted multi-pollutant models and stratified our analysis by age group, sex, and season. Results: The overall relative risk (95% confidence interval (CI)) for PM₁₀, NO₂, and SO₂ at lag 0–1 for hospital admissions due to respiratory disease (RD) were 1.9% (0.5–3.2%), 2.3% (0.6–4%), and 1.1% (−0.2–2.4%), respectively. For cardiovascular disease (CVD), these values were 2.1% (0.6–3.5%), 1% (−0.8–2.8%), and −0.3% (−1.6–1.1%), respectively, per inter-quartile range increase of 12 µg/m³ for PM₁₀, 7.3 µg/m³ for NO₂, and 3.6 µg/m³ for SO₂. The overall cumulative risks for RD per IQR increase in PM₁₀ and NO₂ for children were 2% (0.2–3.9%) and 3.1% (0.7–5.6%), respectively. Conclusion: We found robust associations of daily respiratory disease hospital admissions with daily PM₁₀ and NO₂ concentrations. Associations were strongest among children and warm season for RD.

Air Quality in Africa: Public Health Implications

This review highlights the importance of air quality in the African urban development process. We address connections between air pollution and (a) rapid urbanization, (b) social problems, (c) health impacts, (d) climate change, (e) policies, and (f) new innovations. We acknowledge that air pollution levels in Africa can be extremely high and a serious health threat. The toxic content of the pollution could relate to region-specific sources such as low standards for vehicles and fuels, cooking with solid fuels, and burning household waste. We implore the pursuit of interdisciplinary research to create new approaches with relevant stakeholders. Moreover, successful air pollution research must regard conflicts, tensions, and synergies inherent to development processes in African municipalities, regions, and countries. This includes global relationships regarding climate change, trade, urban planning, and transportation. Incorporating aspects of local political situations (e.g., democracy) can also enhance greater political accountability and awareness about air pollution.

Global research on the air quality status in response to the electrification of vehicles

Electric vehicles (EVs) can substantially decrease atmospheric pollutant emissions, thereby improving air quality, decreasing global warming, and improving human health. In this study, we performed a comprehensive bibliometric analysis using Web of Science to understand the research developments and future perspectives in EVs between 1974 and 2021. The analysis of indicators such as research trends, publication growth, and keywords revealed that most research in the selected timeframe was focused on applying and optimizing the existing technologies of different types of EVs to decrease air pollution and mortality. The changes in air quality owing to such electrification received special attention, with approximately 441 publications preferably in the English language. Among all the retrieved documents, research articles were most common (n = 295; 66.89% of the global output), dominated by the research domains of environmental sciences, followed by energy fuels and transportation science technology. Journal analysis revealed that Sustainability (n = 19, 4.30%) was the leading journal, followed by Journal of Cleaner Production and Science of the Total Environment. The most frequently used keywords were "electric vehicles," "air quality," and "air pollution." The most highly impactful article was published by Jacobson et al. (2005) in Science, with 620 total citations and 38.82 average annual citations. Furthermore, the United States (n = 118; 26.75% of the global output) had the highest publication rate, followed by China and the United Kingdom. The leading institutions were Tsinghua University (n = 16; 3.62% of the global research output) in China, followed by the University of Michigan and Cornell University in the United States. The current analysis warrants more focus on comprehensive analysis employing transport and chemistry modeling and using the latest technology for long life and sustainable batteries. This study provides a basis for future studies on improving air quality through innovative work in the electrification of vehicles.

Effects of air pollutant emission on the prevalence of respiratory and circulatory system diseases in Linyi, China

As a typical industrial city, Linyi has suffered severe atmospheric pollution in recent years. Meanwhile, a high incidence of respiratory and circulatory diseases has been observed in Linyi. The relationship between air pollutants and the prevalence of respiratory and circulatory system diseases in Linyi is still unclear, and therefore, there is an urgent need to assess the human health risks associated with air pollutants. In this study, the number of outpatient visits and spatial distribution of respiratory and circulatory diseases were first investigated. To clarify the correlation between diseases and air pollutant emissions, the residential intake fraction (IF) of air pollutants was calculated. The results showed that circulatory and respiratory diseases accounted for 62.32% of the total causes of death in 2015. The incidence of respiratory diseases was high in the winter, and outpatient visits were observed for more males (60.9%) than females (39.1%). The spatial distribution suggested that outpatient visits for respiratory and circulatory diseases were concentrated in the main urban area of Linyi, including the Hedong District, Lanshan District, and Luozhuang District, and especially at the junction of these three areas. After calculating the IF combined with the characteristics of pollution sources, meteorological conditions, and population data, a high IF value was concentrated in urban and suburban areas, which was consistent with the high incidence of diseases. Moreover, high R values and a significant correlation (R > 0.6, p < 0.05) between outpatient visits and residential IF of air pollutants imply similar spatial distributions of outpatient visits and IF value of residents. The spatial similarity of air pollution and outpatient visits suggested that future air pollution control policies should better reflect the health risks of spatial hotspots. This study can provide a potentially important reference for environmental management and air pollution-related health interventions.

AQI time series prediction based on a hybrid data decomposition and echo state networks

A hybrid AQI time series prediction model is proposed based on EWT-SE-VMD secondary decomposition, ICA (imperialist competitive algorithm) feature selection, and ESN (echo state network) neural network. Firstly, EWT (empirical wavelet transform) and VMD (variational mode decomposition) are used to decompose the original AQI time series into several stable and reliable subseries. Then, the ICA is used to select features of the above subseries for the ESN prediction model. Finally, the optimized feature variables are put into the ESN deep network to establish a prediction model of each AQI subseries and obtain the future AQI index. According to the experimental results of the daily AQI series in Beijing, Tianjin, and Shijiazhuang, we find that (a) among all decomposition methods, the proposed secondary decomposition method (EWT-SE-VMD) performs best in processing data; (b) it is proved that the proposed hybrid model has broad application prospect and research value in the AQI prediction field.

Major climate change-induced risks to human health in South Africa

There are many climatic changes facing South Africa which already have, or are projected to have, a detrimental impact on human health. Here the risks to health due to several alterations in the climate of South Africa are considered in turn. These include an increase in ambient temperature, causing, for example, a significant rise in morbidity and mortality; heavy rainfall leading to changes in the prevalence and occurrence of vector-borne diseases; drought-associated malnutrition; and exposure to dust storms and air pollution leading to the potential exacerbation of respiratory diseases. Existing initiatives and strategies to prevent or reduce these adverse health impacts are outlined, together with suggestions of what might be required in the future to safeguard the health of the nation. Potential roles for the health and non-health sectors as well as preparedness and capacity development with respect to climate change and health adaptation are considered.

Measurements of NOx and Development of Land Use Regression Models in an East-African City

Air pollution causes premature mortality and morbidity globally, but these adverse health effects occur over proportionately in low- and middle-income countries. Lack of both air pollution data and knowledge of its spatial distribution in African countries have been suggested to lead to an underestimation of health effects from air pollution. This study aims to measure nitrogen oxides (NOx), as well as nitrogen dioxide (NO2), to develop Land Use Regression (LUR) models in the city of Adama, Ethiopia. NOx and NO2 was measured at over 40 sites during six days in both the wet and dry seasons. Throughout the city, measured mean levels of NOx and NO2 were 29.0 µg/m3 and 13.1 µg/m3, respectively. The developed LUR models explained 68% of the NOx variances and 75% of the NO2. Both models included similar geographical predictor variables (related to roads, industries, and transportation administration areas) as those included in prior LUR models. The models were validated by using leave-one-out cross-validation and tested for spatial autocorrelation and multicollinearity. The performance of the models was good, and they are feasible to use to predict variance in annual average NOx and NO2 concentrations. The models developed will be used in future epidemiological and health impact assessment studies. Such studies may potentially support mitigation action and improve public health.

Exposure and Public Health Effects of Polycyclic Aromatic Hydrocarbon Compounds in Sub-Saharan Africa: A Systematic Review

BACKGROUND AND AIM

In order to achieve improved global health, environmental health risks that could affect this goal have to be reduced as much as possible. This review thus aimed at determining the exposure levels, health risk assessments, and public health effects of polycyclic aromatic hydrocarbons (PAHs) in sub-Saharan Africa (SSA). This review was developed using guidelines provided for Preferred Reporting Items for Systematic Review and Meta-Analysis. Search was done on Google Scholar, Scopus, and PubMed databases. A study was included if it was carried out in SSA from 2000 to 2020 and written in English language. Fifty-two studies were finally retained and used for the review. Extracted data included the concentrations of 8 selected priority PAHs (including the PAHs prioritized for their carcinogenic potentials), their sources and reported outcomes. In SSA, PAHs exposure has been linked to the use of unprocessed biomass fuels for cooking, release of poorly treated petrochemical effluents into water bodies, and so on. Related public health effects included the occurrence of respiratory, cardiovascular abnormalities, and so on. Others included destruction of natural biodiversity in soil, water, and atmospheric environmental media. Health risk assessments also buttressed the occurrence of these public health effects of PAHs. In SSA, the region is exposed to a substantial amount of PAHs pollution which is associated with deleterious environmental and epidemiological effects. The adoption of healthier forms of energy, a change of attitude to one that favors environmental sustainability, and proper enforcement of environmental regulations are, however, necessary for attaining environmental sanity in SSA.

Intelligent multivariable air-quality forecasting system based on feature selection and modified evolving interval type-2 quantum fuzzy neural network

Owing to the high nonlinearity and noise in the air quality index (AQI), tackling the uncertainties and fuzziness in the forecasting process is still a prevalent problem. Therefore, this study developed an intelligent hybrid air-quality forecasting system based on feature selection and a modified evolving interval type-2 quantum fuzzy neural network (eIT2QFNN), which provides accurate air-quality forecasting information by considering climate influencing factors. The main contributions of this study are as follows. The optimal input structure of the model is determined by the proposed second-stage feature-selection model, which can better extract the influencing variables and remove redundant information. Moreover, a novel multi-objective chaotic Bonobo optimizer algorithm is proposed to improve the eIT2QFNN. The modified eIT2QFNN implements AQI prediction by considering the importance of influencing variables that can cope with the uncertainties and fuzziness in the forecasting process. Finally, the Diebold-Mariano and modified Diebold-Mariano tests are employed to evaluate the performance of the proposed system. The experimental results demonstrate that our proposed system significantly improves the modeling performance in terms of high accuracy and compact structure, and can thus serve as an effective tool for air-quality management.

A scoping review of interventions targeting small-scale, individual-initiated burning practices

BACKGROUND

Ambient outdoor air pollution has been identified as a key risk factor for adverse health outcomes and mortality, particularly in low- and middle-income countries (LMICs). Small-scale, individual-initiated burning activities are significant contributors to local pollutant emissions but are not well studied. We identified articles that describe small-scale burning interventions in order to characterize current trends, implementation science perspectives, and gaps in the literature.

METHODS

We conducted a global search of interventions to reduce ambient air pollution, and then conducted a keyword search among these articles to identify literature regarding interventions to reduce individual-initiated burning. We categorized these articles based on whether burning was discussed as an explicit focus or incidental finding and conducted a full-text analysis. We conducted a supplementary review on anthropological aspects of burning behaviors and burning interventions not captured in our review to inform future recommendations.

RESULTS

Ten articles describing interventions for small-scale, individual-initiated burning were identified. Four articles examined burning as an explicit focus and six discussed burning as an incidental finding. China was the country most represented in our review. All but one of the articles discussed emissions-related outcomes, while only one article discussed health outcomes. Four articles explored factors affecting implementation of interventions and regulations, but none included implementation as a primary objective. The supplementary review revealed a large amount of literature about burning in the context of spiritual and agricultural practices. However, less is known about everyday burning behaviors, such as trash burning and household burning, as well as reasons why people burn.

CONCLUSION

There is a paucity of research that explicitly discusses interventions for small scale, individual-initiated burning practices. Gaps remain in interventions in LMICs most affected by individual-initiated burning, particularly in sub-Saharan Africa. Most of the current literature does not analyze factors affecting effectiveness of interventions and regulations and does not clearly identify reasons why people choose to burn. More research is needed on how to effectively implement interventions to reduce individual-initiated burning, as well as to target key geographic regions and burning sources that continue to be neglected.

Reductions in NO2 burden over north equatorial Africa from decline in biomass burning in spite of growing fossil fuel use, 2005 to 2017

Socioeconomic development in low- and middle-income countries has been accompanied by increased emissions of air pollutants, such as nitrogen oxides [NO_x: nitrogen dioxide (NO₂) + nitric oxide (NO)], which affect human health. In sub-Saharan Africa, fossil fuel combustion has nearly doubled since 2000. At the same time, landscape biomass burning-another important NO_x source-has declined in north equatorial Africa, attributed to changes in climate and anthropogenic fire management. Here, we use satellite observations of tropospheric NO₂ vertical column densities (VCDs) and burned area to identify NO₂ trends and drivers over Africa. Across the northern ecosystems where biomass burning occurs-home to hundreds of millions of people-mean annual tropospheric NO₂ VCDs decreased by 4.5% from 2005 through 2017 during the dry season of November through February. Reductions in burned area explained the majority of variation in NO₂ VCDs, though changes in fossil fuel emissions also explained some variation. Over Africa's biomass burning regions, raising mean GDP density (USD⋅km^-2) above its lowest levels is associated with lower NO₂ VCDs during the dry season, suggesting that economic development mitigates net NO₂ emissions during these highly polluted months. In contrast to the traditional notion that socioeconomic development increases air pollutant concentrations in low- and middle-income nations, our results suggest that countries in Africa's northern biomass-burning region are following a different pathway during the fire season, resulting in potential air quality benefits. However, these benefits may be lost with increasing fossil fuel use and are absent during the rainy season.

Clinical Manifestations and Changes of Haematological Markers among Active People Living in Polluted City: The Case of Douala, Cameroon

Urban air pollution, despite its dangerous health impact, is poorly studied in sub-Saharan Africa (sSA). Epidemiological data on this silent killer are almost non-existent for cities of Cameroon, which seems to be one of the sSA countries where populations are highly exposed to air pollutants. Objective: The present study was conducted in Douala city, and aimed at determining the association of urban air quality degradation with respiratory and systemic health in active populations exposed to air pollutants on a daily basis. Methods: A cross-sectional study was conducted from 2017 to 2019 in 1182 active people consisting of motorbikes drivers (MD), outdoor urban workers (UW), and fuel station sellers (FSS). A standardized questionnaire was used to document participants' data. One hundred and twenty-six (126) motorbike drivers were selected to evaluate the relationship between haematological (white blood cells, platelets) and inflammatory (C-reactive protein-CRP) biomarkers, and air pollution; compared with those of a sixty-five (65) motorbike drivers' control group enrolled in Dschang, another town situated at about 216.3 km from Douala. Results: Among those recruited in urban Douala, some respiratory disorders such as running nostrils, colds, common fever, sore throats, dry cough, wheezing, chest pain, shortness of breath and systemic symptoms such as headaches, eye irritation, conjunctivitis, watery eyes and general tiredness were very common among MD, UW, and FSS. Regarding biological data, blood monocytes, lymphocytes and CRP were found to be significantly increased among selected MD in Douala, compared to control groups in Dschang. Conversely, a more significant decrease in blood neutrophil level was observed among MD in Douala than control groups in Dschang. These changes of haematological markers were significantly associated with place of residence, site of activity, and daily duration. Conclusion: Our results suggest the risk of suffering from respiratory impairments and systemic symptoms with exposure to urban air pollution among active people working near highways in Douala.

Air Pollution Measurements and Land-Use Regression in Urban Sub-Saharan Africa Using Low-Cost Sensors—Possibilities and Pitfalls

Air pollution is recognized as the most important environmental factor that adversely affects human and societal wellbeing. Due to rapid urbanization, air pollution levels are increasing in the Sub-Saharan region, but there is a shortage of air pollution monitoring. Hence, exposure data to use as a base for exposure modelling and health effect assessments is also lacking. In this study, low-cost sensors were used to assess PM2.5 (particulate matter) levels in the city of Adama, Ethiopia. The measurements were conducted during two separate 1-week periods. The measurements were used to develop a land-use regression (LUR) model. The developed LUR model explained 33.4% of the variance in the concentrations of PM2.5. Two predictor variables were included in the final model, of which both were related to emissions from traffic sources. Some concern regarding influential observations remained in the final model. Long-term PM2.5 and wind direction data were obtained from the city’s meteorological station, which should be used to validate the representativeness of our sensor measurements. The PM2.5 long-term data were however not reliable. Means of obtaining good reference data combined with longer sensor measurements would be a good way forward to develop a stronger LUR model which, together with improved knowledge, can be applied towards improving the quality of health. A health impact assessment, based on the mean level of PM2.5 (23 µg/m3), presented the attributable burden of disease and showed the importance of addressing causes of these high ambient levels in the area.

Differential expression of nuclear genes encoding mitochondrial proteins from urban and rural populations in Morocco

Urbanization in low-income countries represents an important inflection point in the epidemiology of disease, with rural populations experiencing high rates of chronic and recurrent infections and urban populations displaying a profile of noncommunicable diseases. To investigate if urbanization alters the expression of genes encoding mitochondrial proteins, we queried gene microarray data from rural and urban populations living in Morocco (GSE17065). The R Bioconductor packages edgeR and limma were used to identify genes with different expression. The experimental design was modeled upon location and sex. Nuclear genes encoding mitochondrial proteins were identified from the MitoCarta2.0 database. Of the 1158 genes listed in the MitoCarta2.0 database, 847 genes (73%) were available for analysis in the Moroccan dataset. The urban-rural comparison with the greatest environmental differences showed that 76.5% of the MitoCarta2.0 genes were differentially expressed, with 97% of the genes having an increased expression in the urban area. Enrichment analysis revealed 367 significantly enriched pathways (adjusted p value < 0.05), with oxidative phosphorylation, insulin secretion and glucose regulations (adj.p values = 6.93E-16) being the top three. Four significantly perturbed KEGG disease pathways were associated with urbanization-three degenerative neurological diseases (Huntington's, Alzheimer's, and Parkinson's diseases) and herpes simplex infection (false discover rate corrected p value (PGFdr) < 0.2). Mitochondrial RNA metabolic processing and translational elongation were the biological processes that had the greatest enrichment (enrichment ratios 14.0 and 14.8, respectively, FDR < 0.5). Our study links urbanization in Morocco with changes in the expression of the nuclear genes encoding mitochondrial proteins.

PM2.5 chemical composition and geographical origin of air masses in Cape Town, South Africa

PM2.5 in the indoor and outdoor environment has been linked in epidemiology studies to the symptoms, hospital admissions and development of numerous health outcomes including death. The study was conducted during April 2017 and April 2018. PM2.5 samples were collected over 24 h and every third day. The mean PM2.5 level was 13.4 μg m-3 (range: 1.17-39.1 μg m-3). PM2.5 levels exceeded the daily World Health Organization air quality guideline (25 μg m-3) on 14 occasions. The mean soot level was 1.38 m-1 × 10-5 (range: 0 to 5.38 m-1 × 10-5). Cl-, NO3 -, SO4 2-, Al, Ca, Fe, Mg, Na and Zn were detected in the PM2.5 samples. The geographical origin of air masses that passed Cape Town was estimated using the Hybrid Single Particle Lagrangian Integrated Trajectory software. Four air masses were identified in the cluster analysis: Atlantic-Ocean-WSW, Atlantic-Ocean-SW, Atlantic-Ocean-SSW and Indian-Ocean. The population of Cape Town may experience various health outcomes from the outdoor exposure to PM2.5 and the chemical composition of PM2.5.

Levels of PM10 and PM2.5 and Respiratory Health Impacts on School-Going Children in Kenya

BACKGROUND

The respiratory system of children is vulnerable to exposure to particulate matter (PM) with a diameter of less than 2.5 and 10 μm (PM2.5 and PM10) or even lower.

OBJECTIVE

This study assessed PM10 and PM2.5 levels and respiratory health impacts on children in schools located in an industrialized suburb in Kenya.

METHOD

The PM10 and PM2.5 levels were sampled from five public primary schools in Athi River Township and a control school during the wet and dry seasons. Outdoor and classroom samples were collected concurrently on an 8-hour mean during school hours on two consecutive days in each school and analyzed using gravimetric techniques. Five hundred and seventy-eight (n = 578) pupils aged 9-14 years from these schools were also evaluated for symptoms of respiratory illnesses and lung function using a questionnaire and spirometric method, respectively, during the same periods.

RESULTS

Indoor median PM10 levels (μg/m3) ranged from 60.8-269.1 and 52.8-232.3 and PM2.5 values (μg/m3) of 17.7-52.4 and 28.5-75.5 during the dry and wet seasons, respectively. The control classrooms had significantly (p <0.05) lower median PM10 levels (μg/m3) of 5.2 and 4.2, and PM2.5 levels (μg/m3) of 3.5 and 3.0 during the respective seasons. Nearly all the classrooms in Athi River schools had PM2.5 and PM10 median levels that exceeded the World Health Organization (WHO) recommended levels. The indoor-to-outdoor ratios varied from 0.35-1.40 and 0.80-2.40 for PM10 and 0.30-0.80 and 0.80-1.40 for PM2.5 during the dry and wet seasons, respectively, suggesting higher levels in the classrooms during the wet season. The relative risk (RR) and odds ratio (OR) presented higher prevalence of respiratory diseases following PM exposure in all the Athi River schools than the control during the dry and wet seasons. At 95% CI, the RR and OR showed strong associations between high PM10 and PM2.5 levels and lung function deficits and vice versa. The association was more prevalent during the wet season.

CONCLUSIONS

The study calls for effective indoor air management programs in school environments to reduce PM exposure and respiratory health impacts.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

The research permit and approvals were obtained from the University of Nairobi/Kenyatta National Hospital Ethics and Research Committee (KNH-UoN ERC Reference: P599/08/2016) and the National Commission for Science, Technology and Innovation (Reference: NACOSTI/P/18/4268/25724).

COMPETING INTERESTS

The authors declare no competing financial interests.

Short term seasonal effects of airborne fungal spores on lung function in a panel study of schoolchildren residing in informal settlements of the Western Cape of South Africa

BACKGROUND

The individual effects of biological constituents of particulate matter (PM) such as fungal spores, on lung function in children are not well known. This study investigated the seasonal short-term effect of daily variation in Alternaria and Cladosporium fungal spores on lung function in schoolchildren.

METHODS

This panel study evaluated 313 schoolchildren in informal settlements of the Western Cape of South Africa, exposed to spores of two commonly encountered fungi, Alternaria and Cladosporium species. The children provided forced-expiratory volume in 1-s (FEV₁) and peak-expiratory flow (PEF) measurements thrice daily for two consecutive school-weeks in summer and winter. Daily PM₁₀ levels, from a stationary ambient air quality monitor and fungal spore levels using spore traps were measured in each study area throughout the year. The effects of Alternaria and Cladosporium spores, on lung function were analysed for lag periods up to five-days, adjusting-for PM₁₀, other pollen exposures, study area, and other host and meteorological factors. Same-day exposure-response curves were computed for both fungal species.

RESULTS

There was more variability in Alternaria spores level with noticeable peaks in summer. There were consistent lag-effects for Alternaria on PEF compared to Cladosporium, with the largest PEF deficit observed in winter (mean deficit: 13.78 L/min, 95%CI: 24.34 to -3.23 L/min) per 10spores/m³ increase in Alternaria spores on lag day-2. Although there were no observable lag-effects for Alternaria and Cladosporium on FEV₁, same-day effects of Cladosporium spores on FEV₁ was present across both seasons. Threshold effects of Alternaria on both PEF and FEV₁ deficits were apparent at levels of 100 spores/m³, but could not be explored for Cladosporium beyond the levels observed during the study.

CONCLUSION

The study provides evidence for the independent effects of daily exposure to ambient fungal spores of Alternaria and Cladosporium on lung function deficits, more especially in winter for PEF.

Dispersion Characteristics of Hazardous Gas and Exposure Risk Assessment in a Multiroom Building Environment

The leakage of hazardous chemicals during storage and transport processes is a kind of commonly occurring accident that can pose a serious threat to people's lives and property. This paper aims to investigate the airflow and dispersion characteristics of hazardous gas around a multiroom building, and evaluate the corresponding exposure risks. The effects on indoor air quality (IAQ) when polluted air enters a room under different indoor and external conditions were examined by using a computational fluid dynamics technique. First, the numerical model established herein was verified by the available wind-tunnel experimental data, and acceptable agreement was found between the predicted and measured velocities. Subsequently, the effects of different natural ventilation paths, wall porosities and outdoor pollutant source characteristics on the airflow and contaminant distribution were evaluated. The study not only reveals the airflow pattern and concentration distribution in indoor spaces under different natural ventilation conditions but also quantitatively analyzes the relationship between the probability of death and the corresponding source strength under the circumstance of pollutant leakage near a building. The results can be useful for the prevention and control of hazardous chemical gas leakages and provide some guidance on evacuation after an accidental or routine leakage.

Toxic Site Identification Program in Azerbaijan

The need to protect communities from hazardous waste is an important agenda for any nation. Although pollutant management and policy development are attempted in many developing countries, it is not always successful due to limited funds, project resources, and access to trained experts to conduct toxic site identification projects. For this reason, Pure Earth created the Toxic Site Identification Program (TSIP). The goal of the TSIP program is to provide reliable information and data that identifies location of toxic sites and the level of toxic severity. TSIP is significant because it provides developing countries a database of ranked toxic sites identified as hazardous risk to human health. For example, Azerbaijan is one of the most polluted post-Soviet nations, but has limited resources to address and manage its polluted sites. The Azerbaijani TSIP database is the first reliable data source that identifies hazardous pollutants in the country. Our study is significant because it discusses how the TSIP labels and ranks the level of toxic severity to human health. It is also the first data source in Azerbaijan that identifies which Soviet legacy toxic sites are affecting local communities. Although our study is specific to Azerbaijan, the TSIP method can be applied to nations with similar data limitations and the need for a database that identifies country specific environmental and hazardous locations. The data sampling method and results are mapped and accompanied by tables of the collected pollutant types to identify communities at greatest health-risk to legacy toxic sites.

Environmental health research challenges in Africa: Insights from symposia organized by the ISEE Africa Chapter at ISES-ISEE 2018

Supplemental Digital Content is available in the text.

Personal NO2 and Volatile Organic Compounds Exposure Levels are Associated with Markers of Cardiovascular Risk in Women in the Cape Town Region of South Africa

Exposure to ambient NO2 and benzene, toluene ethyl-benzene and m+p- and o-xylenes (BTEX) is associated with adverse cardiovascular effects, but limited information is available on the effects of personal exposure to these compounds in South African populations. This 6-month follow-up study aims to determine 7-day personal ambient NO2 and BTEX exposure levels via compact passive diffusion samplers in female participants from Cape Town, and investigate whether exposure levels are associated with cardiovascular risk markers. Overall, the measured air pollutant exposure levels were lower compared to international standards. NO2 was positively associated with systolic and diastolic blood pressure (SBP and DBP), and inversely associated with the central retinal venular equivalent (CRVE) and mean baseline brachial artery diameter. o-xylene was associated with DBP and benzene was strongly associated with carotid intima media thickness (cIMT). Our findings showed that personal air pollution exposure, even at relatively low levels, was associated with several markers of cardiovascular risk in women residing in the Cape Town region.

Chemical and Biological Components of Urban Aerosols in Africa: Current Status and Knowledge Gaps

Aerosolized particulate matter (PM) is a complex mixture that has been recognized as the greatest cause of premature human mortality in low- and middle-income countries. Its toxicity arises largely from its chemical and biological components. These include polycyclic aromatic hydrocarbons (PAHs) and their nitro-derivatives (NPAHs) as well as microorganisms. In Africa, fossil fuel combustion and biomass burning in urban settings are the major sources of human exposure to PM, yet data on the role of aerosols in disease association in Africa remains scarce. This review is the first to examine studies conducted in Africa on both PAHs/NPAHs and airborne microorganisms associated with PM. These studies demonstrate that PM exposure in Africa exceeds World Health Organization (WHO) safety limits and carcinogenic PAHs/NPAHs and pathogenic microorganisms are the major components of PM aerosols. The health impacts of PAHs/NPAHs and airborne microbial loadings in PM are reviewed. This will be important for future epidemiological evaluations and may contribute to the development of effective management strategies to improve ambient air quality in the African continent.

Proliferation of low-cost sensors. What prospects for air pollution epidemiologic research in Sub-Saharan Africa?

Addressing the worsening urban air quality situation in Sub-Saharan Africa (SSA) is proving increasingly difficult owing to paucity of data on air pollution levels and also, lack of local evidence on the magnitude of the associated health effects. There is therefore the urgent need to expand air quality monitoring (AQM) networks in SSA to enable the conduct of high quality epidemiologic studies to help inform policies aimed at addressing air pollution and the associated health effects. In this commentary, I explore the prospects that the proliferation of low-cost sensors in recent times holds for air pollution epidemiologic research in SSA. This commentary is timely because most SSA governments do not see investments in air pollution control that requires assembling a network of sophisticated and prohibitively expensive instrumentation for AQM as necessary for improving and protecting public health. I conclude that, in a region that is bereft of air pollution data, the growing influx of low-cost sensors represents an excellent opportunity for bridging the data gap to inform air pollution control policies and regulations for public health protection. However, it is essential that only the most promising sensor technologies that performs creditably well in the harsh environmental conditions of the region are promoted.

Land Use Regression Modelling of Outdoor NO₂ and PM2.5 Concentrations in Three Low Income Areas in the Western Cape Province, South Africa

Air pollution can cause many adverse health outcomes, including cardiovascular and respiratory disorders. Land use regression (LUR) models are frequently used to describe small-scale spatial variation in air pollution levels based on measurements and geographical predictors. They are particularly suitable in resource limited settings and can help to inform communities, industries, and policy makers. Weekly measurements of NO₂ and PM_2.5 were performed in three informal areas of the Western Cape in the warm and cold seasons 2015–2016. Seasonal means were calculated using routinely monitored pollution data. Six LUR models were developed (four seasonal and two annual) using a supervised stepwise land-use-regression method. The models were validated using leave-one-out-cross-validation and tested for spatial autocorrelation. Annual measured mean NO₂ and PM_2.5 were 22.1 μg/m³ and 10.2 μg/m³, respectively. The NO₂ models for the warm season, cold season, and overall year explained 62%, 77%, and 76% of the variance (R²). The PM_2.5 annual models had lower explanatory power (R² = 0.36, 0.29, and 0.29). The best predictors for NO₂ were traffic related variables (major roads, bus routes). Local sources such as grills and waste burning sites appeared to be good predictors for PM_2.5, together with population density. This study demonstrates that land-use-regression modelling for NO₂ can be successfully applied to informal peri-urban settlements in South Africa using similar predictor variables to those performed in Europe and North America. Explanatory power for PM_2.5 models is lower due to lower spatial variability and the possible impact of local transient sources. The study was able to provide NO₂ and PM_2.5 seasonal exposure estimates and maps for further health studies.