Ambient particulate matter and biomass burning:an ecological time series study of respiratory and cardiovascular hospital visits in northern Thailand

Background Exposure to particulate matter (PM) emitted from biomass burning is an increasing concern, particularly in Southeast Asia. It is not yet clear how the source of PM influences the risk of an adverse health outcome. The objective of this study was to quantify and compare health risks of PM from biomass burning and non-biomass burning sources in northern Thailand. Methods We collected ambient air pollutant data (PM with a diameter of < 10 μm [PM10], PM2.5, Carbon Monoxide [CO], Ozone [O3], and Nitrogen Dioxide [NO2]) from ground-based monitors and daily outpatient hospital visits in Thailand during 2014–2017. Outpatient data included chronic lower respiratory disease (CLRD), ischaemic heart disease (IHD), and cerebrovascular disease (CBVD). We performed an ecological time series analysis to evaluate the association between daily air pollutants and outpatient visits. We used the 90th and 95th percentiles of PM10 concentrations to determine days of exposure to PM predominantly from biomass burning. Results There was significant intra annual variation in PM10 levels, with the highest concentrations occurring during March, coinciding with peak biomass burning. Incidence Rate Ratios (IRRs) between daily PM10 and outpatient visits were elevated most on the same day as exposure for CLRD = 1.020 (95% CI: 1.012 to 1.028) and CBVD = 1.020 (95% CI: 1.004 to 1.035), with no association with IHD = 0.994 (95% CI: 0.974 to 1.014). Adjusting for CO tended to increase effect estimates. We did not find evidence of an exposure response relationship with levels of PM10 on days of biomass burning. Conclusions We found same-day exposures of PM10 to be associated with certain respiratory and cardiovascular outpatient visits. We advise implementing measures to reduce population exposures to PM wherever possible, and to improve understanding of health effects associated with burning specific types of biomass in areas where such large-scale activities occur.This study was funded by the Medical Research Council (MRC) (MR/R006210/1) and the Thailand Research Fund (TRF) (RDG603009)

Factors Influencing the Quality of Drinking Water From Vending Machines in the Inner City of Bangkok

Objective: To investigate coliform contamination in drinking water from vending machines in the Rajvithi area of Bangkok.Study Design: Cross-sectional studyMethods: Associated environmental factors were observed and self-administered questionnaires conducted. In total, 123 drinking-water samples were collected to test coliform bacteria contamination.Results: Coliform bacteria were detected in 28.5% of samples. Links were found between coliform contamination and filter cleaning practices in 57 maintenance persons' responses. Filters cleaned &lt; 3 times per year were at higher risk of coliform contamination (OR 14.49, 95% CI 1.76-125.00). A negative association was found between coliform contamination and vending-machine filters' being cleaned within 100 days (OR 0.21, 95% CI 0.05-0.83).Conclusion: A negative association was found between coliform contamination and vending-machine filters' being cleaned within 100 days (OR 0.21, 95% CI 0.05-0.83). These results emphasized the importance of effective vending-machine maintenance and monitoring drinking-water quality

Socio-ecological dimensions of infectious diseases in Southeast Asia

Understanding and measuring the consequences of environmental pollution on human health remains a challenge. Several barriers arise, with the difficulty in identifying uncommon pathologies but also with the limited knowledge of the real health status of populations that depends on the supply and use of care. In an effort to assess these barriers, we chose a study area severely affected by agricultural intensification to investigate the potential and visible impact of water pollution on human health. Located in northern Thailand, the study area includes a watershed, its reservoir and the irrigated area downstream. A questionnaire-based survey was conducted to assess the exposure of 297 households to potential water pollutions and understand their behaviour regarding the use of water and recourse to health services. The observations are discussed in the light of the epidemiological records provided by the Ministry of Public Health for the same area. The study shows the heterogeneity of the epidemiological data and the difficulty to assess the sanitary risk. Despite the small size of the study area, inequalities are observed, with remote populations having a poorer access to water with occasional shortage and a limited use of health services. In this context, the intensification of agriculture and the massive use of pesticides and fertilizers are likely to have serious consequences on human health. However, the impact of potential environmental pollution is not visible from the epidemiological records, because of a difficult diagnosis, a lack of consultation when symptoms are reversible and the long latency before clinical symptoms are apparent (example of cancers). Prevention and incentive from health authorities should help in reducing this risk

Water and health: what is the risk and visible burden of the exposure to environmental contaminations? Insights from a questionnaire-based survey in Northern Thailand

International audienceUnderstanding and measuring the consequences of environmental pollution on human health remains a challenge. Several barriers arise, with the difficulty in identifying uncommon pathologies but also with the limited knowledge of the real health status of populations that depends on the supply and use of care. In an effort to assess these barriers, we chose a study area severely affected by agricultural intensification to investigate the potential and visible impact of water pollution on human health. Located in northern Thailand, the study area includes a watershed, its reservoir and the irrigated area downstream. A questionnaire-based survey was conducted to assess the exposure of 297 households to potential water pollutions and understand their behaviour regarding the use of water and recourse to health services. The observations are discussed in the light of the epidemiological records provided by the Ministry of Public Health for the same area. The study shows the heterogeneity of the epidemiological data and the difficulty to assess the sanitary risk. Despite the small size of the study area, inequalities are observed, with remote populations having a poorer access to water with occasional shortage and a limited use of health services. In this context, the intensification of agriculture and the massive use of pesticides and fertilizers are likely to have serious consequences on human health. However, the impact of potential environmental pollution is not visible from the epidemiological records, because of a difficult diagnosis, a lack of consultation when symptoms are reversible and the long latency before clinical symptoms are apparent (example of cancers). Prevention and incentive from health authorities should help in reducing this risk

A health impact assessment of long-term exposure to particulate air pollution in Thailand

Particulate air pollution causes a spectrum of adverse health effects affecting the respiratory, cardiovascular, neurological, and metabolic systems that are hypothesised to be driven by inflammation and oxidative stress. Millions of premature deaths each year are attributed to exposure to ambient particulate matter (PM). We quantified health and economic impacts from long-term exposure to ambient PM2.5 in the population of Thailand for 2016. We collected data on ambient PM2.5 concentrations from automatic monitoring stations across Thailand over 1996-2016. We used historic exposure to PM2.5 to estimate the mortality in each province from lower respiratory infections (LRIs), stroke, chronic obstructive pulmonary disease, lung cancer, and ischaemic heart disease, and also assessed diabetes mortality, as well as incident cases of dementia and Parkinson's disease, in supplementary analyses. We applied risk estimates from the Global Exposure Mortality Model to calculate attributable mortality and quantify disability-adjusted life years (DALYs); we based economic costs on the value of a statistical life (VSL). We calculated 50 019 (95% confidence interval [CI]: 42 189-57 849) deaths and 508 918 (95% CI: 438 345-579 492) DALYs in 2016 attributed to long-term PM2.5 exposure in Thailand. Population attributable fractions ranged from 20% (95% CI: 10% to 29%) for stroke to 48% (95% CI: 27% to 63%) for LRIs. Based on the VSL, we calculated a cost of US$60.9 billion (95$ 51.3-70.4 billion), which represents nearly 15% of Thailand's gross domestic product in 2016. While progress has been made to reduce exposure to ambient PM2.5 in Thailand, continued reductions based on stricter regulatory limits for PM2.5 and other air pollutants would help prolong life, and delay, or prevent, onset of cardiorespiratory and other diseases.</p

Environmental factors and public health policy associated with human and rodent infection by leptospirosis: a land cover-based study in Nan province, Thailand

International audienceLeptospirosis incidence has increased markedly since 1995 in Thailand, with the eastern and northern parts being the most affected regions, particularly during flooding events. Here, we attempt to overview the evolution of human prevalence during the past decade and identify the environmental factors that correlate with the incidence of leptospirosis and the clinical incidence in humans. We used an extensive survey of Leptospira infection in rodents conducted in 2008 and 2009 and the human incidence of the disease from 2003 to 2012 in 168 villages of two districts of Nan province in Northern Thailand. Using an ad-hoc developed land-use cover implemented in a geographical information system we showed that humans and rodents were not infected in the same environment/habitat in the land-use cover. High village prevalence was observed in open habitat near rivers for the whole decade, or in 2008–2009 mostly in rice fields prone to flooding, whereas infected rodents (2008–2009) were observed in patchy habitat with high forest cover, mostly situated on sloping ground areas. We also investigated the potential effects of public health campaigns conducted after the dramatic flood event of 2006. We showed that, before 2006, human incidence in villages was explained by the population size of the village according to the environmental source of infection of this disease, while as a result of the campaigns, human incidence in villages after 2006 appeared independent of their population size. This study confirms the role of the environment and particularly land use, in the transmission of bacteria, emphasized by the effects of the provincial public health campaigns on the epidemiological pattern of incidence, and questions the role of rodents as reservoirs