Urban and rural exposure to indoor air pollution from domestic biomass and coal burning across China

Although indoor air pollution (IAP) from solid fuel use in the households of the developing countries is estimated to be one of the main health risks worldwide, there is little knowledge of the actual exposure experienced by large populations. We have developed a method to estimate exposure to PM(10) from IAP for large populations, applied to different demographic groups in China. On a national basis we find that 80%-90% of exposure in the rural population results from IAP. For the urban population the contribution is somewhat lower, about 50%-60%. Average exposure is estimated at 340 microg/m(3) (SD 55) in southern cities, and 440 microg/m(3) (SD 40) in northern cities. For the rural population we find average exposure to be 750 microg/m(3) (SD 100) and 680 microg/m(3) (SD 65) in the south and north respectively. Quite surprisingly our results indicate that the heavily polluted northern provinces, largely dependent on coal and believed to have the population with the largest exposure burden, turn out to have medium exposure when IAP is included. We find that the largest exposure burden is in counties relying heavily on biomass, and that there are only small gender differences in exposure.     

Indoor air pollution in developing countries: recommendations for research

Available studies indicate that indoor air pollution (IAP) from household cooking and space heating apparently causes substantial ill-health in developing countries where the majority of households rely on solid fuels (coal or biomass as wood, crop residues, and dung), but there are many remaining uncertainties. To pin down impacts in order to effectively target interventions, research is particularly needed in three areas: (1) epidemiology: case-control studies for tuberculosis (TB) and cardiovascular disease in women and randomized intervention trials for childhood acute respiratory diseases and adverse pregnancy outcomes; (2) exposure assessment: techniques and equipment for inexpensive exposure assessment at large scale, including national level surveys; (3) interventions: engineering and dissemination approaches for improved stoves, fuels, ventilation, and behavior that reliably and economically reduce exposure. There are also important potential synergisms between efforts to reduce greenhouse gas emissions and those to reduce health-damaging emissions from solid-fuel stoves. The substitution of biomass by coal being considered in some countries should be pursued with caution because of the known serious health effects of household coal use.     

Household CO and PM measured as part of a review of China's National Improved Stove Program

In 2001-2003, a team of researchers from the United States and China performed an independent, multidisciplinary review of China's National Improved Stove Program carried out since the 1980s. As part of a 3500-household survey, a subsample of 396 rural households were monitored for particulate matter less than 4 microm (PM(4)) in kitchens and living rooms over 24 h, of which 159 were measured in both summer and winter. Carbon monoxide was measured in a 40% subsample. The results of this indoor air quality (IAQ) component indicate that for nearly all household stove or fuel groupings, PM(4) levels were higher than - and sometimes more than twice as high as - the national PM(10) standard for indoor air (150 microg PM(10)/m(3)). If these results are typical, then a large fraction of China's rural population is now chronically exposed to levels of pollution far higher than those determined by the Chinese government to harm human health. Further, we observed highly diverse fuel usage patterns in these regions in China, supporting the observations in the household survey of multiple stoves being present in many kitchens. Improved stoves resulted in reduced PM(4) from biomass fuel combinations, but still not at levels that meet standards, and little improvement was observed in indoor pollution levels when other unimproved stoves were present in the same kitchen. As many households change fuels according to daily and seasonal factors, resulting in different seasonal concentrations in living rooms and kitchens, assessing health implications from fuel use requires longitudinal evaluation of fuel use and IAQ levels, combined with accurate time-activity information. PRACTICAL IMPLICATIONS: Leaving aside the difficult issue of enforcement, it is uncertain whether Chinese household IAQ standards represent realistic objectives for current attainment given current patterns of energy consumption in rural China, which rely so heavily on unprocessed solid fuels. Even when used with chimneys, these fuels emit substantial pollution into the household environment. It is probable that low-emission technologies involving gaseous/liquid fuels or high combustion - efficiency biomass stoves need to be promoted in order to achieve these standards for the greater part of the population.     

Indoor air quality for poor families: new evidence from Bangladesh

Poor households in Bangladesh depend heavily on wood, dung and other biomass fuels for cooking. This paper provides a detailed analysis of the implications for indoor air pollution (IAP), drawing on new 24-h monitoring data for respirable airborne particulates (PM10). A stratified sample of 236 households was selected in Dhaka and Narayanganj, with a particular focus on fuel use, cooking locations, structural materials, ventilation practices, and other potential determinants of exposure to IAP. At each household, PM10 concentrations in the kitchen and living room were monitored for a 24-h period during December, 2003-February, 2004. Concentrations of 300 microg/m3 or greater are common in our sample, implying widespread exposure to a serious health hazard. A regression analysis for these 236 households was then conducted to explore the relationships between PM10 concentrations, fuel choices and a large set of variables that describe household cooking and ventilation practices, structure characteristics and building materials. As expected, our econometric results indicate that fuel choice significantly affects indoor pollution levels: natural gas and kerosene are significantly cleaner than biomass fuels. However, household-specific factors apparently matter more than fuel choice in determining PM10 concentrations. In some biomass-burning households, concentrations are scarcely higher than in households that use natural gas. Our results suggest that cross-household variation is strongly affected by structural arrangements: cooking locations, construction materials, and ventilation practices. A large variation in PM10 was also found during the 24-h cycle within households. For example, within the 'dirtiest' firewood-using household in our sample, readings over the 24-h cycle vary from 68 to 4864 microg/m3. Such variation occurs because houses can recycle air very quickly in Bangladesh. After the midday meal, when ventilation is common, air quality in many houses goes from very dirty to reasonably clean within an hour. Rapid change also occurs within households: diffusion of pollution from kitchens to living areas is nearly instantaneous in many cases, regardless of internal space configuration, and living-area concentrations are almost always in the same range as kitchen concentrations. By implication, exposure to dangerous indoor pollution levels is not confined to cooking areas. To assess the broader implications for poor Bangladeshi households, we extrapolate our regression results to representative 600 household samples from rural, peri-urban and urban areas in six regions: Rangpur in the north-west, Sylhet in the north-east, Rajshahi and Jessore in the west, Faridpur in the center, and Cox's Bazar in the south-east. Our results indicate great geographic variation, even for households in the same per capita income group. This variation reflects local differences in fuel use and, more significantly, construction practices that affect ventilation. For households with per capita income 相似文献   

Impacts of stove/fuel use and outdoor air pollution on chemical composition of household particulate matter

Biomass combustion for cooking and heating releases particulate matter (PM_2.5) that contributes to household air pollution. Fuel and stove types affect the chemical composition of household PM, as does infiltration of outdoor PM. Characterization of these impacts can inform future exposure assessments and epidemiologic studies, but is currently limited. In this study, we measured chemical components of PM_2.5 (water-soluble organic matter [WSOM], ions, black carbon, elements, organic tracers) in rural Chinese households using traditional biomass stoves, semi-gasifier stoves with pelletized biomass, and/or non-biomass stoves. We distinguished households using one stove type (traditional, semi-gasifier, or LPG/electric) from those using multiple stoves/fuels. WSOM concentrations were higher in households using only semi-gasifier or traditional stoves (31%-33%) than in those with exclusive LPG/electric stove (13%) or mixed stove use (12%-22%). Inorganic ions comprised 14% of PM in exclusive LPG/electric households, compared to 1%-5% of PM in households using biomass. Total PAH content was much higher in households that used traditional stoves (0.8-2.8 mg/g PM) compared to those that did not (0.1-0.3 mg/g PM). Source apportionment revealed that biomass burning comprised 27%-84% of PM_2.5 in households using biomass. In all samples, identified outdoor sources (vehicles, dust, coal combustion, secondary aerosol) contributed 10%-20% of household PM_2.5.     

Patterns and predictors of personal exposure to indoor air pollution from biomass combustion among women and children in rural China

Indoor air pollution (IAP) from domestic biomass combustion is an important health risk factor, yet direct measurements of personal IAP exposure are scarce. We measured 24-h integrated gravimetric exposure to particles < 2.5 μm in aerodynamic diameter (particulate matter, PM?.?) in 280 adult women and 240 children in rural Yunnan, China. We also measured indoor PM?.? concentrations in a random sample of 44 kitchens. The geometric mean winter PM?.? exposure among adult women was twice that of summer exposure [117 μg/m3 (95% CI: 107, 128) vs. 55 μg/m3 (95% CI: 49, 62)]. Children's geometric mean exposure in summer was 53 μg/m3 (95% CI: 46, 61). Indoor PM?.? concentrations were moderately correlated with women's personal exposure (r=0.58), but not for children. Ventilation during cooking, cookstove maintenance, and kitchen structure were significant predictors of personal PM?.? exposure among women primarily cooking with biomass. These findings can be used to develop exposure assessment models for future epidemiologic research and inform interventions and policies aimed at reducing IAP exposure. PRACTICAL IMPLICATIONS: Our results suggest that reducing overall PM pollution exposure in this population may be best achieved by reducing winter exposure. Behavioral interventions such as increasing ventilation during cooking or encouraging stove cleaning and maintenance may help achieve these reductions.     

Nitrogen dioxide and household fuel use in the Pakistan

More than half the world's population use biomass fuels as a household energy source and, hence, face significant exposure to a number of air pollutants. In Pakistan about 90% of rural households and 22% of urban households use biomass fuels. In order to assess the levels of NO₂ in the residential micro-environment, two sampling campaigns were carried out at different times of the year (summer and winter) at an urban and two rural sites during 2005 and 2007. Rural site I used biomass fuels while natural gas was utilized at rural site II and the urban site. In winter NO₂ concentrations at all three sites were higher in the kitchens than living rooms and outdoors. ANOVA showed that, although, there was a significant difference among NO₂ concentrations in the kitchens, living rooms and courtyards, at all the three sites, there was no significant different between kitchens using biomass fuels and natural gas. During the summer NO₂ levels fell sharply at both rural sites (from 256 μg/m³ and 242 μg/m³ to 51 μg/m³ and 81 μg/m³). However at the urban site the mean levels were slightly higher in summer (234 μg/m³) than in winter (218 μg/m³). The considerable seasonal variation at the rural sites was due to a shift of indoor kitchens to open outdoor kitchens at rural site I and more ventilation at rural site II during summer. There was no significant difference between kitchens using biomass (site I) or natural gas (site II), however the kitchens at rural site II and urban site showed a significant difference. Overall fuel selection showed no significant effect on NO₂ levels. However the NO₂ concentrations may pose a significant threat to the health of people, especially women and children.     

Effect of Indoor air pollution from biomass and solid fuel combustion on symptoms of preeclampsia/eclampsia in Indian women

Available evidence concerning the association between indoor air pollution (IAP) from biomass and solid fuel combustion and preeclampsia/eclampsia is not available in developing countries. We investigated the association between exposure to IAP from biomass and solid fuel combustion and symptoms of preeclampsia/eclampsia in Indian women by analyzing cross‐sectional data from India's third National Family Health Survey (NFHS‐3, 2005–2006). Self‐reported symptoms of preeclampsia/eclampsia during pregnancy such as convulsions (not from fever), swelling of legs, body or face, excessive fatigue or vision difficulty during daylight, were obtained from 39 657 women aged 15–49 years who had a live birth in the previous 5 years. Effects of exposure to cooking smoke, ascertained by type of fuel used for cooking on preeclampsia/eclampsia risk, were estimated using logistic regression after adjusting for various confounders. Results indicate that women living in households using biomass and solid fuels have two times higher likelihood of reporting preeclampsia/eclampsia symptoms than do those living in households using cleaner fuels (OR = 2.21; 95%: 1.26–3.87; P = 0.006), even after controlling for the effects of a number of potentially confounding factors. This study is the first to empirically estimate the associations of IAP from biomass and solid fuel combustion and reported symptoms suggestive of preeclampsia/eclampsia in a large nationally representative sample of Indian women and we observed increased risk. These findings have important program and policy implications for countries such as India, where large proportions of the population rely on polluting biomass fuels for cooking and space heating. More epidemiological research with detailed exposure assessments and clinical measures of preeclampsia/eclampsia is needed in a developing country setting to validate these findings.     

Chimney stoves modestly improved Indoor Air Quality measurements compared with traditional open fire stoves: results from a small‐scale intervention study in rural Peru

Nearly half of the world's population depends on biomass fuels to meet domestic energy needs, producing high levels of pollutants responsible for substantial morbidity and mortality. We compare carbon monoxide (CO) and particulate matter (PM_2.5) exposures and kitchen concentrations in households with study‐promoted intervention (OPTIMA‐improved stoves and control stoves) in San Marcos Province, Cajamarca Region, Peru. We determined 48‐h indoor air concentration levels of CO and PM_2.5 in 93 kitchen environments and personal exposure, after OPTIMA‐improved stoves had been installed for an average of 7 months. PM_2.5 and CO measurements did not differ significantly between OPTIMA‐improved stoves and control stoves. Although not statistically significant, a post hoc stratification of OPTIMA‐improved stoves by level of performance revealed mean PM_2.5 and CO levels of fully functional OPTIMA‐improved stoves were 28% lower (n = 20, PM_2.5, 136 μg/m³ 95% CI 54–217) and 45% lower (n = 25, CO, 3.2 ppm, 95% CI 1.5–4.9) in the kitchen environment compared with the control stoves (n = 34, PM_2.5, 189 μg/m³, 95% CI 116–261; n = 44, CO, 5.8 ppm, 95% CI 3.3–8.2). Likewise, although not statistically significant, personal exposures for OPTIMA‐improved stoves were 43% and 17% lower for PM_2.5 (n = 23) and CO (n = 25), respectively. Stove maintenance and functionality level are factors worthy of consideration for future evaluations of stove interventions.     

Exposure to household air pollution from biomass‐burning cookstoves and HbA1c and diabetic status among Honduran women

Household air pollution from biomass cookstoves is estimated to be responsible for more than two and a half million premature deaths annually, primarily in low and middle‐income countries where cardiometabolic disorders, such as Type II Diabetes, are increasing. Growing evidence supports a link between ambient air pollution and diabetes, but evidence for household air pollution is limited. This cross‐sectional study of 142 women (72 with traditional stoves and 70 with cleaner‐burning Justa stoves) in rural Honduras evaluated the association of exposure to household air pollution (stove type, 24‐hour average kitchen and personal fine particulate matter [PM_2.5] mass and black carbon) with glycated hemoglobin (HbA1c) levels and diabetic status based on HbA1c levels. The prevalence ratio (PR) per interquartile range increase in pollution concentration indicated higher prevalence of prediabetes/diabetes (vs normal HbA1c) for all pollutant measures (eg, PR per 84 μg/m³ increase in personal PM_2.5, 1.49; 95% confidence interval [CI], 1.11‐2.01). Results for HbA1c as a continuous variable were generally in the hypothesized direction. These results provide some evidence linking household air pollution with the prevalence of prediabetes/diabetes, and, if confirmed, suggest that the global public health impact of household air pollution may be broader than currently estimated.     

Hypertension with elevated levels of oxidized low-density lipoprotein and anticardiolipin antibody in the circulation of premenopausal Indian women chronically exposed to biomass smoke during cooking

This study aims to investigate whether indoor air pollution (IAP) from biomass fuel use was associated with hypertension, platelet hyperactivity, and elevated levels of oxidized low-density lipoprotein (oxLDL) and anticardiolipin antibody (aCL). We enrolled 244 biomass fuel-using (median age 34 year) and 236 age-matched control women who cooked with liquefied petroleum gas (LPG). Enzyme-linked immunosorbent assay was used to measure oxLDL in plasma and aCL in serum, flow cytometry for P-selectin expression on platelet and reactive oxygen species (ROS) generation by leukocytes, aggregometry for platelet aggregation, spectrophotometry for superoxide dismutase (SOD) in erythrocytes, and laser photometer for particulate matter <10 and 2.5 μm in diameter (PM(10) and PM(2.5), respectively) in cooking areas. Biomass users had three times more particulate pollution in kitchen, had higher prevalence of hypertension (29.5 vs. 11.0% in control, P < 0.05), elevated oxLDL (170.6 vs. 45.9 U/l; P < 0.001), platelet P-selectin expression (9.1% vs. 2.4%), platelet aggregation (23.2 vs. 15.9 Ohm), raised aCL IgG (28.7% vs. 2.1%), IgM (8.6% of vs. 0.4%), and ROS (44%) but depleted (13%) SOD. After controlling potential confounders, the changes were positively associated with PM(10) and PM(2.5) in indoor air, suggesting a positive association between IAP and increased cardiovascular risk. PRACTICAL IMPLICATIONS: The study showing high risk of developing cardiovascular diseases (CVD) among poor, underprivileged women in their reproductive ages in rural India is important from public health perspectives. It may motivate the government and the regulatory agencies of the country to take a serious note of the indoor air pollution (IAP) from biomass fuel use as it threatens the health of millions of women, children, and the elderly who mostly stay indoor. We hope the findings will strengthen the demand for setting up a standard for indoor air quality in the country in the line of national ambient air quality standard. The findings may also inspire the authorities to take measures for the reduction in IAP by improving housing, kitchen ventilation, and cook stoves. Moreover, the parameters used in this study can be utilized for large, population-based studies to identify women at a higher risk of developing CVD so that medical intervention can be taken at the formative stage of a disease.     

Measuring the exposure of infants and children to indoor air pollution from biomass fuels in The Gambia

Indoor air pollution (IAP) from biomass fuels contains high concentrations of health damaging pollutants and is associated with an increased risk of childhood pneumonia. We aimed to design an exposure measurement component for a matched case-control study of IAP as a risk factor for pneumonia and severe pneumonia in infants and children in The Gambia. We conducted co-located simultaneous area measurement of carbon monoxide (CO) and particles with aerodynamic diameter <2.5 microm (PM(2.5)) in 13 households for 48 h each. CO was measured using a passive integrated monitor and PM(2.5) using a continuous monitor. In three of the 13 households, we also measured continuous PM(2.5) concentration for 2 weeks in the cooking, sleeping, and playing areas. We used gravimetric PM(2.5) samples as the reference to correct the continuous PM(2.5) for instrument measurement error. Forty-eight hour CO and PM(2.5) concentrations in the cooking area had a correlation coefficient of 0.80. Average 48-h CO and PM(2.5) concentrations in the cooking area were 3.8 +/- 3.9 ppm and 361 +/- 312 microg/m3, respectively. The average 48-h CO exposure was 1.5 +/- 1.6 ppm for children and 2.4 +/- 1.9 ppm for mothers. PM(2.5) exposure was an estimated 219 microg/m3 for children and 275 microg/m3 for their mothers. The continuous PM(2.5) concentration had peaks in all households representing the morning, midday, and evening cooking periods, with the largest peak corresponding to midday. The results are used to provide specific recommendations for measuring the exposure of infants and children in an epidemiological study. PRACTICAL IMPLICATIONS: Measuring personal particulate matter (PM) exposure of young children in epidemiological studies is hindered by the absence of small personal monitors. Simultaneous measurement of PM and carbon monoxide suggests that a combination of methods may be needed for measuring children's PM exposure in areas where household biomass combustion is the primary source of indoor air pollution. Children's PM exposure in biomass burning homes in The Gambia is substantially higher than concentrations in the world's most polluted cities.     

Fine particle number and mass concentration measurements in urban Indian households

Fine particle number concentration (D(p)>10 nm, cm(-3)), mass concentrations (approximation of PM(2.5), microg m(-3)) and indoor/outdoor number concentration ratio (I/O) measurements have been conducted for the first time in 11 urban households in India, 2002. The results indicate remarkable high indoor number and mass concentrations and I/O number concentration ratios caused by cooking. Besides cooking stoves that used liquefied petroleum gas (LPG) or kerosene as the main fuel, high indoor concentrations can be explained by poor ventilation systems. Particle number concentrations of more than 300,000 cm(-3) and mass concentrations of more than 1000 microg m(-3) were detected in some cases. When the number and mass concentrations during cooking times were statistically compared, a correlation coefficient r>0.50 was observed in 63% of the households. Some households used other fuels like wood and dung cakes along with the main fuel, but also other living activities influenced the concentrations. In some areas, outdoor combustion processes had a negative impact on indoor air quality. The maximum concentrations observed in most cases were due to indoor combustion sources. Reduction of exposure risk and health effects caused by poor indoor air in urban Indian households is possible by improving indoor ventilation and reducing penetration of outdoor particles.     

Indoor fine particulate matter and demographic,household, and wood stove characteristics among rural US homes heated with wood fuel

Household heating using wood stoves is common practice in many rural areas of the United States (US) and can lead to elevated concentrations of indoor fine particulate matter (PM_2.5). We collected 6-day measures of indoor PM_2.5 during the winter and evaluated household and stove-use characteristics in homes at three rural and diverse study sites. The median indoor PM_2.5 concentration across all homes was 19 µg/m³, with higher concentrations in Alaska (median = 30, minimum = 4, maximum = 200, n = 10) and Navajo Nation homes (median = 29, minimum = 3, maximum = 105, n = 23) compared with Montana homes (median = 16, minimum = 2, maximum = 139, n = 59). Households that had not cleaned the chimney within the past year had 65% higher geometric mean PM_2.5 compared to those with chimney cleaned within 6 months (95% confidence interval [CI]: −1, 170). Based on a novel wood stove grading method, homes with low-quality and medium-quality stoves had substantially higher PM_2.5 compared to homes with higher-quality stoves (186% higher [95% CI: 32, 519] and 161% higher; [95% CI:27, 434], respectively). Our findings highlight the need for, and complex nature of, regionally appropriate interventions to reduce indoor air pollution in rural wood-burning regions. Higher-quality stoves and behavioral practices such as regular chimney cleaning may help improve indoor air quality in such homes.     

A survey on energy consumption in rural households in the fringes of Xian city

A survey, in the form of a questionnaire, of energy consumption patterns in residential households in the rural fringe of Xian city was undertaken during the winter of 2003/2004. More than 200 households were sampled during the survey. The status of fuel consumption, including the use of biomass fuels for cooking and space heating, was investigated. The types of stoves, purpose of the stove use, and characteristics of the residential houses and residents were also reported and analyzed.The purpose of the survey was to clarify the status of energy consumption and to estimate emissions of greenhouse gases and air pollutants in rural areas of China, from the environmental perspective of climate change and indoor to continental scale air pollution. In rural areas of China, biomass (wood and agricultural waste, such as stalks, corn canes and twigs, branches of wood) is the type of fuel most commonly used. It emits several air pollutants: particulate matter (PM), CO, NMHCs, CH₄ and high levels of black carbon (BC) – a greenhouse effect aerosol, and organic carbon (OC) – a cooling effect aerosol. However, CO₂ emissions from biomass burning are assumed to be zero because of carbon neutrality.From this survey it would then be possible to analyze the fundamentals of emission reduction potential, for air pollutants and greenhouse gases, from the rural household sector in China.     

Analysis of urban-rural population dynamics for China

The population dynamics of China are presented in a multiregional demographic model using regional estimates or mortality and migration based on the 1% population sample survey in 1987. An open ended population account is generated for period cohort a, gender g of region i (urban) and j (rural) using population, birth, death, and migration. Demographic rates and equations for flows of nonsurviving migrants of period cohort a of gender g are estimated using the forward demographic rate definition. Out-migration rates for period cohort a of gender g are defined by migration flow divided by the initial population. The death rate for period cohort A1 and A are estimated using a single region method. Death and migration rates are simultaneously estimated with an iterative procedure. The population accounts estimates and demographic rates are provided for the period ending 1986-87 for male births, males in period cohorts 10 and 20, female births, and females in period cohorts 10 and 20. The urban and rural population projection model is based on the population accounts concept and assumes fixed rates of mortality, migration, and normal fertility for the base year 1987. The results of this projection are a population of 1090 million that will grow to 1304 million in 2000, 1720 million in 2050, and 1791 million in 2087. Urban population will expand from 44.2% in 1988 to 46.6% in 2000, and 54.7% in 2087. The labor population of males 18-65 years and females 18-60 years will increase from 58.8% in 1988 to 59.7% in 2000 and decline to 58.4% by 2087. The old age population of males 65 years and females 60 years will increase from 6.5% in 1988 to 7.9% in 2000, and 16.3% in 2087. The mean age increased from 28.3 years in 1988 to 37 in 2087. Urban population may be underprojected; migration problems are recognized. Fertility also is likely to decline. An alternative projection (B) is given to account for the U-shape distribution and urban fertility of 1.8 in 2000, increasing to and stabilizing at 2.2 in 2020, such that population estimates for 2000 are 1291 and 1524 for 2087 with a peak in 2048 of 1573. A faster fertility decline is also used to generate projection C. The author's projections A, B, and C, which are based on more recent data and a more realistic model, are than the "objective projection" and than the "warning projection" generated by China's Population Census Office based on 1982 census data.     

Mapping indoor overheating and air pollution risk modification across Great Britain:A modelling study

Housing has long been thought to play a significant role in population exposure to environmental hazards such as high temperatures and air pollution.However,there is sparse data describing how housing may modify heat and air pollution exposure such that housing's role in poor health and mortality from these hazards may be estimated.This paper describes the development of individual-address level indoor overheating and air pollution risk modifiers for Great Britain,for use alongside historical weather,outdoor air pollution,population socio-economic data,and mortality data in a large-scale epidemiological investigation.A geographically-referenced housing stock database was developed using the Homes Energy Efficiency Database(HEED)and the English Housing Survey(EHS).Simulations of unique combinations of building,fabric,occupation,and environment were run using a modelling framework developed for Energy Plus8.0,estimating indoor temperature metrics,indoor/outdoor ratio of pollution from outdoor sources,and indoor air pollution from multiple indoor sources.Results were compiled,matched back to individual properties in HEED,and mapped using Geographical Information Systems(GIS).Results indicate urban areas had higher numbers of buildings prone to overheating,reduced levels indoor air pollution from outdoor sources,and higher air pollution from indoor sources relative to rural areas,driven largely by variations in building types.The results provide the first national-scale quantitative estimate of heat and indoor air pollution modification by dwellings,aggregated at levels suitable for inclusion in health analysis.     

Impact and uncertainty of a traffic management intervention: population exposure to polycyclic aromatic hydrocarbons

In urban areas, road traffic is a major source of carcinogenic polycyclic aromatic hydrocarbons (PAH), thus any changes in traffic patterns are expected to affect PAH concentrations in ambient air. Exposure to PAH and other traffic-related air pollutants has often been quantified in a deterministic manner that disregards the various sources of uncertainty in the modelling systems used. In this study, we developed a generic method for handling uncertainty in population exposure models. The method was applied to quantify the uncertainty in population exposure to benzo[a]pyrene (BaP) before and after the implementation of a traffic management intervention. This intervention would affect the movement of vehicles in the studied area and consequently alter traffic emissions, pollutant concentrations and population exposure. Several models, including an emission calculator, a dispersion model and a Geographic Information System were used to quantify the impact of the traffic management intervention. We established four exposure zones defined by distance of residence postcode centroids from major road or intersection. A stochastic method was used to quantify the uncertainty in the population exposure model. The method characterises uncertainty using probability measures and propagates it applying Monte Carlo analysis. The overall model predicted that the traffic management scheme would lead to a minor reduction in mean population exposure to BaP in the studied area. However, the uncertainty associated with the exposure estimates was much larger than this reduction. The proposed method is generic and provides realistic estimates of population exposure to traffic-related pollutants, as well as characterises the uncertainty in these estimates. This method can be used within a decision support tool to evaluate the impact of alternative traffic management policies.     

Spatial analysis of annual air pollution exposure and mortality

The aim of this study was to relate ambient air pollution levels to mortality in Auckland, New Zealand. We used urban airshed modelling and GIS-based techniques to quantify long-term exposure to ambient air pollution levels and associated mortality. After adjusting for age, sex, ethnicity, socio-economic status, and urban/rural domicile there was a 1.3% (95%CI: 1-1.5%) increase in non-external cause mortality, and 1.8% (95%CI: 1.5-2.1%) increase in circulatory and respiratory causes per 1 microg/m(3) increase in annual average NO(2). Based on these exposure-response relationships and applying an annual average threshold of 13 microg/m(3), the average annual (for 1996-1999) number of people estimated to die from non-external causes and circulatory and respiratory causes attributable to air pollution in Auckland is 268 (95% range: 227-310) (3.9% of total all cause deaths) and 203 (95% range: 169-237) (5.9% of total circulatory and respiratory deaths) per year, respectively. The number of attributable deaths found in this study are consistent with a previous New Zealand risk assessment using a different methodology, and is approximately twice the number of people dying from motor vehicle accidents in the region, which is on average (1996-1999) 103 per year. The GIS-based exposure maps identify high exposure areas for policy developers and planners in a simple and realistic manner. Taken together with overseas studies the study provides additional evidence that long-term exposure to poor air quality, even at levels below current standards, is a hazard to the public health.     

Sources of heavy metals and polycyclic aromatic hydrocarbons in urban stormwater runoff

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals were measured in road debris collecting in urban areas and in the suspended sediment (SS) component of runoff from two stormwater catchments in Dunedin, New Zealand. Levels in the road debris ranged from 119-527 microg/g for lead, 50-464 microg/g for copper, 241-1 325 microg/g for zinc and 1.20-11.6 microg/g for sigma16PAH. The SS from the largely rural catchment (20% urban) had similar concentrations to the road debris, indicating that this urban material was the main source of the contaminants measured in the stormwater. Similar PAH fingerprint profiles and isomer ratios indicative of dominant pyrogenic (combustion) sources were also found in these two groups of materials. The SS from the 100% urban catchment contained 2- to 6-fold higher concentrations of metals and 10-fold greater levels of sigma16PAH. The higher levels of lead and copper were probably a result of industrial land uses in this catchment, while the additional zinc was linked to an abundance of zinc-galvanised roofing iron in the catchment's residential suburbs. The PAH profiles and isomer ratios were different for this urban catchment and suggested that a disused gasworks was contributing PAHs to the stormwater runoff.