Health and Economic Benefits of Air Pollution Reductions in Vietnam During 2020-2021.

Objectives: This paper explores the potential reduction in the number of deaths and the corresponding economic benefits in Vietnam that could have arisen from the decreased in concentrations of particulate matter with a diameter of 2.5 µm or less (PM2.5) and nitrogen dioxide (NO2). Methods: Using Global Exposure Mortality Models, we estimated the potential health and economic benefits on people aged 25 and above across Vietnam's 63 provinces. The counterfactual scenario assumed reducing PM2.5 and NO2 concentrations to levels observed during the two COVID-19 epidemic waves in 2021 with national lockdowns and activity restrictions. Results: In 2019, PM2.5 concentrations ranged from 12.8 to 40.8 µg/m3 while NO2 concentrations ranged between 2.9 and 36.98 µg/m3. The reduced levels of PM2.5 and NO2 resulted in 3,807 (95% CI: 2,845-4,730) and 2,451 (95% CI: 2,845-4,730) avoided deaths of adults aged 25 and above due to non-injury-related causes, respectively. Considering that every prevented death represents potential tangible and intangible cost savings, reduced levels of PM2.5 and NO2 concentrations during COVID-19 restrictions would have resulted in economic benefits of $793.0 million (95% CI: 592.7-985.4) and $510.6 million (95% CI: 381.3-634.9), respectively. Conclusion: The COVID-19 lockdown led to decreased PM2.5 and NO2 concentrations, benefiting health and economy in Vietnam. Our findings highlight the potential advantages of implementing air quality control policies in the country.

Emerging infectious disease, the household built environment characteristics, and urban planning: Evidence on avian influenza in Vietnam.

Recent concerns with pandemic outbreaks of human disease and their origins in animal populations have ignited concerns regarding connections between Emerging Infectious Diseases (EID) and development. As disasters, health, and infectious disease become part of planning concern (Matthew & McDonald, 2007), greater focus on household infrastructure and EID disease outbreaks among poultry is warranted. Following Spencer (2013), this study examines the relationship between the mix of household-scale water supplies, sanitation systems, and construction materials, and Highly Pathogenic Avian Influenza (HPAI) among poultry in a developing country: Vietnam. Findings of our multivariate logistic regressions suggest that a non-linear, Kuznets-shaped urban transition (Spencer, 2013) has an independent effect on the outbreak of HPAI, especially as it relates to household-level sanitation infrastructure. We conclude that the Kuznets-shape development of household infrastructure characteristics in Vietnam play a significant role in explaining where poultry outbreaks occur. Using secondary data from the Census of Population and Housing, and the Agricultural Census at the District and Commune levels for the country of Vietnam, we performed logistic regression to test the relationship between outbreaks of HPAI in poultry and newly-developed "coherence indices" (Spencer, 2013) of household water supply, sanitation, and construction materials that measure nonlinear, transitional development. Results show that district-scale coherence indices are negatively and independently correlated with HPAI outbreaks, especially for sanitation. Findings also suggest that community-scale coherence of urban infrastructures is a powerful tool for predicting where HPAI poultry outbreaks are likely to occur, thereby providing health planners new tools for efficient surveillance.

Perceived Risk of Avian Influenza and Urbanization in Northern Vietnam.

Highly pathogenic avian influenza (HPAI) is an important public health concern because of potential for widespread morbidity and mortality in humans and poultry and associated devastating economic losses. We examined how perceptions of the risk of HPAI in poultry vary across communes/wards in the north of Vietnam at different levels of urbanization (rural, peri-urban, urban). Analyses of questionnaire responses from 1081 poultry raisers suggested that the perceived risk of HPAI in poultry was highest in peri-urban and rural settings. We also found that perceived risk was higher when respondents rated settings in which they did not live and that the process of change is related to perceived risk. Compared with others, respondents in peri-urban areas reported less disease management planning; respondents in rural areas reported less ability to separate infected poultry. These findings are consistent with, and add to, the limited previous research on the perceived risk of HPAI in poultry in developing countries. What is new in the present findings is that we describe how urbanization is related to people's perceptions of and ability to respond appropriately to variations in their environment. In particular, the inability to respond is not necessarily because of an inability to perceive change. Rather, rapid and extensive change poses different challenges for poultry management as communes move from rural to peri-urban to urban settings. Our results suggest that health promotion campaigns should address the perceptions and needs of poultry raisers in different settings.

An Alternative Vaccination Approach for The Prevention of Highly Pathogenic Avian Influenza Subtype H5N1 in The Red River Delta, Vietnam -A Geospatial-Based Cost-Effectiveness Analysis.

This study addresses the tradeoff between Vietnam's national poultry vaccination program, which implemented an annual two-round HPAI H5N1 vaccination program for the entire geographical area of the Red River Delta during the period from 2005-2010, and an alternative vaccination program which would involve vaccination for every production cycle at the recommended poultry age in high risk areas within the Delta. The ex ante analysis framework was applied to identify the location of areas with high probability of HPAI H5N1 occurrence for the alternative vaccination program by using boosted regression trees (BRT) models, followed by weighted overlay operations. Cost-effectiveness of the vaccination programs was then estimated to measure the tradeoff between the past national poultry vaccination program and the alternative vaccination program. Ex ante analysis showed that the focus areas for the alternative vaccination program included 1137 communes, corresponding to 50.6% of total communes in the Delta, and located primarily in the coastal areas to the east and south of Hanoi. The cost-effectiveness analysis suggested that the alternative vaccination program would have been more successful in reducing the rate of disease occurrence and the total cost of vaccinations, as compared to the national poultry vaccination program.

Evidence for the Convergence Model: The Emergence of Highly Pathogenic Avian Influenza (H5N1) in Viet Nam.

Building on a series of ground breaking reviews that first defined and drew attention to emerging infectious diseases (EID), the 'convergence model' was proposed to explain the multifactorial causality of disease emergence. The model broadly hypothesizes disease emergence is driven by the co-incidence of genetic, physical environmental, ecological, and social factors. We developed and tested a model of the emergence of highly pathogenic avian influenza (HPAI) H5N1 based on suspected convergence factors that are mainly associated with land-use change. Building on previous geospatial statistical studies that identified natural and human risk factors associated with urbanization, we added new factors to test whether causal mechanisms and pathogenic landscapes could be more specifically identified. Our findings suggest that urbanization spatially combines risk factors to produce particular types of peri-urban landscapes with significantly higher HPAI H5N1 emergence risk. The work highlights that peri-urban areas of Viet Nam have higher levels of chicken densities, duck and geese flock size diversities, and fraction of land under rice or aquaculture than rural and urban areas. We also found that land-use diversity, a surrogate measure for potential mixing of host populations and other factors that likely influence viral transmission, significantly improves the model's predictability. Similarly, landscapes where intensive and extensive forms of poultry production overlap were found at greater risk. These results support the convergence hypothesis in general and demonstrate the potential to improve EID prevention and control by combing geospatial monitoring of these factors along with pathogen surveillance programs.

Environmental justice in the context of commuters' exposure to CO and PM10 in Bangalore, India.

The Information Technology (IT) industry in the globalizing city of Bangalore has transformed the socio-economic characteristics of the city. The intent of this study, developed from an environmental justice framework, was to determine whether air pollutant exposure while commuting to and from work is related to a commuter's income characteristics and whether differences are larger for the IT economy when compared with a traditional manufacturing-oriented economy of the city. The study measured exposures to CO and PM10 using personal samplers for a sample of employees of a traditional public sector manufacturing industry (n=20) and an IT industry (n=26). This approach overcomes the methodological limitations of previous environmental justice studies. Socio-economic characteristics were obtained from a questionnaire-based survey of 436 employees in two firms. The results do not support the environmental justice hypothesis for commuting in Bangalore mainly because longer commuting times of higher-income groups offsets the benefits of lower pollutant concentrations. The study nevertheless demonstrates the use of personal exposure for environmental justice assessments.

An exploration of how perceptions of the risk of avian influenza in poultry relate to urbanization in Vietnam.

This research examined how perceptions of outbreaks of highly pathogenic avian influenza (HPAI) subtype H5N1 in poultry are related to urbanization. Via in-depth interviews with village leaders, household farmers, and large farm operators in modern, transitional, and traditional communes in the north of Vietnam, we explored behaviors, attitudes, cultural values, and traditions that might amplify or attenuate HPAI outbreaks. We also explored conceptualizations of urbanization and its impacts on animal husbandry and disease outbreaks. Qualitative theme analyses identified the key impacts, factors related to HPAI outbreaks, and disease prevention and management strategies. The analyses also highlighted how urbanization improves some aspects of life (e.g., food security, family wealth and health, more employment opportunities, and improved infrastructure), but simultaneously poses significant challenges for poultry farming and disease management. Awareness of qualitative aspects of HPAI risk perceptions and behaviors and how they vary with urbanization processes may help to improve the prevention and management of emerging infectious diseases.

Exposure of infants to outdoor and indoor air pollution in low-income urban areas - a case study of Delhi.

Indoor air pollution is potentially a very serious environmental and public health problem in India. In poor communities, with the continuing trend in biofuel combustion coupled with deteriorating housing conditions, the problem will remain for some time to come. While to some extent the problem has been studied in rural areas, there is a dearth of reliable data and knowledge about the situation in urban slum areas. The microenvironmental model was used for assessing daily-integrated exposure of infants and women to respirable suspended particulates (RSP) in two slums of Delhi - one in an area of high outdoor pollution and the other in a less polluted area. The study confirmed that indoor concentrations of RSP during cooking in kerosene-using houses are lesser than that in wood-using houses. However, the exposure due to cooking was not significantly different across the two groups. This was because, perhaps due to socioeconomic reasons, kerosene-using women were found to cook for longer durations, cook inside more often, and that infants in such houses stayed in the kitchen for longer durations. It was observed that indoor background levels during the day and at nighttime can be exceedingly high. We speculate that this may have been due to resuspension of dust, infiltration, unknown sources, or a combination of these factors. The outdoor RSP levels measured just outside the houses (near ambient) were not correlated with indoor background levels and were higher than those reported by the ambient air quality monitoring network at the corresponding stations. More importantly, the outdoor levels measured in this study not only underestimated the daily-integrated exposure, but were also poorly correlated with it.

Chapter three: methodology of exposure modeling.

In this chapter, the concept of exposure assessment and its evolution is introduced, and evaluated by critically appraising the pertinent literature as it applies to exposures to Particulate Matter (PM). Exposure measurement or estimation methodologies and models are reviewed. Three exposure/measurement methodologies are assessed. Estimation methods focus on source evaluation and attribution, sources include those outdoors and indoors as well as in occupational and in-transit environments. Fate and transport models and their inputs are addressed to estimate concentrations outdoors and indoors; source attribution techniques help focus on the contributing sources. Activity pattern techniques are also reviewed and their use in exposure models to estimate inhalation exposure to PM is presented. Deterministic, regression and other stochastic models of exposure to PM are reviewed and evaluated. Strengths, limitations, assumptions and affirmations of the use of exposure assessment as an integral component of risk assessment and risk management are discussed in the conclusions and discussions section of this work.

Policy uses of particulate exposure estimates.

This paper reviews the uses of particulate exposure estimates for science and policy. We propose a set of normative factors to guide the selection and application of various approaches for exposure assessment. For exposure estimates intended for use in support of the development or air pollution regulations or selection of control strategies, the proposed criteria include--compatibility with policy scope and scale, cost-effectiveness, characterization of uncertainty, political and institutional feasibility, and sensitivity to framing. For exposure assessment in support of epidemiological research, key criteria are-compatability with the specific hypothesis being tested, and compatibility with the temporal and spatial scale of analysis. The various major approaches for estimation of exposure--direct and indirect measurement, empirical and physical modeling--are catalogued and compared with these proposed criteria.

Modeling exposure to particulate matter.

Exposure assessment, a component of risk assessment, links sources of pollution with health effects. Exposure models are scientific tools used to gain insights into the processes affecting exposure assessment. The purpose of this paper is to review the process and methodology of estimating inhalation exposure to particulate matter (PM) using various types of models. Three types of models are discussed in the paper. Indirect type of models are physical models that employ inventories of outdoor and indoor sources and their emission rates to identify major sources contributing to exposure to PM, and use fate and transport and indoor air quality models to estimate PM concentrations at receptor sites. PM concentrations and time spent by a subject at each receptor site are input variables to the conventional exposure model that estimates the desired exposure levels. Direct type models use measured exposure or exposure concentrations in conjunction with information obtained from questionnaires to formulate exposure regression models. Stochastic models use exposure measurements, estimates can also be used, to formulate exposure population distributions and investigate associated uncertainty and variability. Since models developed using databases from western countries are not necessarily applicable in developing countries, the difference in requirements among western and developing countries is highlighted in the paper. Employment of exposure modeling methods in developing countries requires development of local information. Such information includes local outdoor and indoor source inventories, local or regional meteorological conditions, adjustment of indoor models to reflect local building construction conditions, and use of questionnaires to obtain local time budget and activity patterns of the subject population.

Accessible tools for classification of exposure to particles.

In this manuscript we describe various alternative tools to estimate exposure to particles. We stress methods that are cost effective and widely available to those throughout the world. The use of surrogate measures arises from the need to estimate exposures of large populations where individual measurements are not feasible, for predictive modeling or to assess exposures rapidly before personal monitoring campaigns can be implemented. In addition, an understanding of the relationship between exposures and surrogate variables can be useful in helping to identify mitigation strategies to reduce exposures. We have separated the various alternative exposure measures by the scales of impact, describing approaches to assess regional, urban and household indoor air quality. In particular, we emphasize scenarios that are relevant to particle exposures that may be experienced in developing countries as a result of domestic energy use for cooking and heating. In all cases the approaches we describe are applicable to large populations as the data collection techniques are relatively inexpensive and specifically applicable on a population basis for risk assessment, epidemiology or to evaluate determinants of exposure and health outcomes. The ultimate use of the assessed exposures will determine the relevance of potential surrogate measures.