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 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   

Indoor air pollution from particulate matter emissions in different households in rural areas of Bangladesh

Indoor air pollution from the combustion of traditional biomass fuels (wood, cow dung, and crop wastes) is a significant public health problem predominantly for poor populations in many developing countries. It is particularly problematic for the women who are normally responsible for food preparation and cooking, and for infants/young children who spend time around their mothers near the cooking area. Airborne particulate matter (PM) samples were collected from cooking and living areas in homes in a rural area of Bangladesh to investigate the impact of fuel use, kitchen configurations, and ventilation on indoor air quality and to apportion the source contributions of the measured trace metals and BC concentrations. Lower PM concentrations were observed when liquefied petroleum gas (LPG) was used for cooking. PM concentrations varied significantly depending on the position of kitchen, fuel use and ventilation rates. From reconstructed mass (RCM) calculations, it was found that the major constituent of the PM was carbonaceous matter. Soil and smoke were identified as components from elemental composition data. It was also found that some kitchen configurations have lower PM concentrations than others even with the use of low-grade biomass fuels. Adoption of these kitchen configurations would be a cost-effective approach in reducing exposures from cooking in these rural areas.     

Indoor and outdoor BTX levels in German cities

On the basis of the ongoing study INGA (INdoor exposure and Genetics in Asthma), Germany's most detailed and standardized epidemiological study on indoor exposure to both allergens in house dust and volatile compounds in the air of the home environment has been performed. The purpose of this paper is to describe the spatial and seasonal variability of indoor and outdoor BTX (Benzene, toluene, ethyl benzene, ortho-xylene, meta- and para-xylene) concentrations for the study period from June 1995 to November 1996. Within this framework, air concentrations of volatile organic compounds (BTX) were measured in 204 households in Erfurt (Eastern Germany) and 201 households in Hamburg (Western Germany). BTX sampling was conducted over one week using OVM 3500 passive diffusion sampling devices in the indoor (living room and bedroom) and outdoor environment (outside the window of the living room). Indoor and outdoor median BTX concentrations in Erfurt were slightly, but significantly higher than those in Hamburg. This gap was most pronounced in the levels of indoor toluene (37.3 microg/m3 for Erfurt and 20.5 microg/m3 for Hamburg, P < 0.0001). In both cities, winter indoor and outdoor concentrations for the five compounds exceeded the summer values. Outdoor concentrations of ethyl benzene and ortho-xylene were very low (50% < L.D.). In general, the indoor BTX air concentrations were significantly higher than the outdoor concentra- tions, the lowest I/O ratios were found in the case of benzene. Living room and bedroom values for the five compounds were highly correlated (Spearman coefficient 0.5-0.9). Despite the better insulation of the homes in West Germany, no indication for the expected higher indoor concentrations of BTX in the West could be found. The strong and yet undiscovered indoor source for toluene in East Germany might lead to a further increase in the indoor air load in those homes in the East, which undergo renovations which will lead to improved insulation.     

Comparison of indoor air quality in electrified and un-electrified dwellings in rural South African villages

A feasibility study was undertaken to assess the suitability of South African rural villages due to be electrified, for the purposes of undertaking a large-scale study of the impact of reductions in indoor air pollution on acute lower respiratory infections. As part of the feasibility study, quantitative assessments of indoor air pollution in non-electrified and electrified dwellings were performed. Concurrent measurements were made of levels of respirable particulate matter (RSP-stationary), and carbon monoxide (CO) (personal on children <18 months), as well as a stationary co-located with RSP) over a 24-h period in 52 un-electrified and 53 electrified dwellings. The proportion of dwellings with a detectable 24-h concentration of RSP was significantly higher in un-electrified (48.1%) than electrified dwellings (24.5%) (chi(2) = 6.30 on 1 d.f., P = 0.012). In addition a Kruskal-Wallis test (adjusted for ties) showed that the distribution of RSP differed between un-electrified and electrified areas (Kruskal-Wallis chi(2) = 8.20 on 1 d.f., P = 0.014). In those dwellings where some RSP was detected, the amount was on average higher in the un-electrified areas (mean 162 microg/m(3), median 107 microg/m(3)) than in the electrified areas (mean 77 microg/m(3), median 37.5 microg/m(3)). Stationary (kitchen CO) levels in un-electrified dwellings ranged from 0.36 to 20.95 p.p.m. However, in electrified dwellings, kitchen levels ranged from 0 to 11.8 p.p.m. When mean concentrations of CO were compared between electrified and un-electrified dwellings using a two-sample t-test (on log-transformed data), there was overwhelming evidence (P = 0.0004) that the mean level of log (CO) in the kitchen was higher in the un-electrified areas (1.25 vs. 0.69) and also overwhelming evidence (P < 0.0001) that the mean level of log (CO) on the child was higher in the un-electrified areas (0.83 vs. 0.34). Of importance in terms of both policy and for a potential future large-scale study, is that measurable significant differences in indoor pollutants between electrified and un-electrified dwellings during summer were found in spite of only partial transition to electricity use for cooking in electrified villages. PRACTICAL IMPLICATIONS: It is estimated that at least two-thirds of all households in the developing world are still primary dependent on biomass fuels and coal. This situation applies to 59% of rural households in South Africa. In the last decade a program of providing electricity to three million homes has been underway in South Africa. Among others this intervention aims to reduce exposure to pollutants from burning biomass fuels and reduce detrimental health effects, especially in young children. This study provides scientific evidence that electrified homes in South African villages have lower levels of air pollution (RSP and CO) relative to their non-electrified counterparts.     

Indoor and outdoor personal exposure to benzene in Athens, Greece

OBJECTIVE: To evaluate the exposure of urban inhabitants to atmospheric benzene in Athens, Greece. METHODS: Fifty non-smoker volunteers from selected occupational groups and their homes were monitored by passive air samplers for six 5-day periods during a year. An activity diary was completed during each sampling period and relevant data were collected by a questionnaire at the beginning of the study. Additional data on urban levels on benzene were also available. RESULTS: Average benzene home and personal levels in six monitoring campaigns varied between 6.0-13.4 and 13.1-24.6 microg/m(3), respectively. Urban levels varied between 15.4 and 27.9 microg/m(3) with an annual mean of 20.4 microg/m(3). Wind speed seems to determine largely home levels and personal exposure. Proximity to busy road holds also an important influence on indoor benzene levels. Adjusted for seasonal or climate variation, other significant prognostic factors of personal exposure were home levels, total time spent outdoors and transportation mean. Time spent outdoors explains the strong relationship between occupation and personal levels of exposure. Wind had similar effect in clearing indoor and urban pollution in Athens; lessen personal exposure and home levels about 2-2.5 microg/m(3) per 1 m/s increase in speed. CONCLUSIONS: Factors related to climate (use of non-absorbent materials for wall and floor covering and frequent ventilation) might be one explanation for homes' high clearing rate. Our exposure pattern, which suggests that outdoors work give the greater contribution to benzene exposure of Athens citizens, is uncommon in northern towns of Europe. Policy makers have to take in account these differences in establishing guidelines for ambient benzene exposure.     

Assessment through environmental and biological measurements of total daily exposure to volatile organic compounds of office workers in Milan, Italy

Personal exposure to total volatile organic compounds (TVOCs), benzene and toluene of 100 Milan office workers was assessed through personal air monitoring at home, in the office, and during commuting. Biological monitoring was performed by measuring blood benzene and toluene concentrations together with urinary trans-trans-muconic acid (t,t-MA) and cotinine at the end of the monitoring period. The geometric means of the total 24-h personal exposure were 514 micrograms/m3 for TVOCs, 21.2 micrograms/m3 for benzene and 35.2 micrograms/m3 for toluene. Daily exposure to the volatile organic compounds was almost totally determined by indoor exposure at home and in the office, with a minor contribution in the transport means. An important factor determining exposure to benzene was found to be tobacco smoke, both for active smokers and for non-smokers exposed to environmental tobacco smoke (ETS). All the mean levels of the biological indicators were significantly higher in active smokers than in non-smoking subjects non-exposed to ETS; urine cotinine and t,t-MA levels were also significantly higher in non-smokers exposed to ETS than in non-smokers non-exposed to ETS.     

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.     

Particulate exposure and size distribution from wood burning stoves in Costa Rica

Biomass fuel is the most common energy source for cooking and space heating in developing countries. Biomass fuel combustion causes high levels of indoor air pollutants including particulates and other combustion by-products. We measured indoor air quality in 23 houses with a wood burning stove in rural residential areas of Costa Rica. Daily PM2.5, PM10 and CO concentrations, and particle size distribution were simultaneously measured in the kitchen. When a wood burning stove was used during the monitoring period, average daily PM2.5 and PM10 concentrations were 44 and 132 microg/m3, respectively. Average CO concentrations were between 0.5 and 3.3 ppm. All houses had a particle size distribution of either one or two peaks at around 0.7 and 2.5 microm aerodynamic diameters. The particulate levels increased rapidly during cooking and decreased quickly after cooking. The maximum peak particulate levels ranged from 310 to 8170 microg/m3 for PM2.5 and from 500 to 18900 microg/m3 for PM10 in all houses. Although the 24-h particulate levels in this study are lower than the National Ambient Air Quality Standards of PM2.5 and PM10, it is important to note that people, especially women and children, are exposed to extremely high levels of particulates during cooking.     

Factors affecting individual exposure to NO2 in Genoa (northern Italy)

The individual exposure to nitrogen dioxide (NO2) of 89 volunteers living in Genoa, a large port city of northern Italy, was investigated with personal passive diffusion tubes in February-March 2000. The data were related to NO2 concentration in the kitchen and bedroom as measured by static samplers. Volunteers included students, workers and housewives living in three areas of Genoa differing by street traffic and industrial plant location. The kitchen samples showed higher (47.00+/-16.5 microg/m3) NO2 concentrations than those from the bedroom (24.78+/-9.8 microg/m3); overall indoor NO2 concentrations were lower in the Eastern area of Genoa, where outdoor pollution is lower. Students were the volunteer group with the lowest exposure rate (24.9+/-7.8 microg/m3 vs. 44.3+/-10.1 microg/m3 for workers and 40.0+/-13.4 microg/m3 for housewives). This difference is related to the fact that students spend more time indoors, where pollution levels are lower. The main household characteristics which were shown to affect personal NO2 exposure were (a) the presence of a chimney equipped with an active aspiration device in the kitchen and (b) the heating system.     

Residents' particle exposures in six different communities in Taiwan

Exposure assessment studies for particulates have been conducted in several U.S. and European cities; however, exposure data remain sparse for Asian populations whose cultural practices and living styles are distinct from those in the developed world. This study assessed personal PM(10) exposure in urban residents and evaluated PM(10) indoor/outdoor levels in communities with different characteristics. Important factors of personal PM(10) exposure in Taiwan were explored. Sampling was conducted in 6 communities in Taiwan, two in each of the three major metropolitan areas. Up to nine non-smoking volunteers in each community carried personal samplers for 24 h. The geometric means (GM) of PM(10) in personal, indoor and outdoor samples were 76.3 microg/m(3) (geometric standard deviation, GSD=1.8), 73.4 microg/m(3) (GSD=1.5), and 85.8 microg/m(3) (GSD=1.7), respectively. It was found that outdoor levels rather than indoor levels contributed significantly to personal exposure. The important exposure factors include the time spent outdoors and on transportation, riding a motorcycle, passing by factories, cooking or being in the kitchen, and incense burning at home. Motorcycle riding and the proximity to factories are related to the special living and housing characteristics in Taiwan, while incense burning and Chinese cooking are culture-related. Motorcyclists experienced an average of 27.7 microg/m(3) higher PM(10) than others, while subjects passing by a factory were exposed to an average of 38.4 microg/m(3) higher PM(10) than others. Effective control and public education should be applied to reduce the contribution of these PM exposure sources.     

Exhaust ventilation in attached garages improves residential indoor air quality

Previous research has shown that indoor benzene levels in homes with attached garages are higher than homes without attached garages. Exhaust ventilation in attached garages is one possible intervention to reduce these concentrations. To evaluate the effectiveness of this intervention, a randomized crossover study was conducted in 33 Ottawa homes in winter 2014. VOCs including benzene, toluene, ethylbenzene, and xylenes, nitrogen dioxide, carbon monoxide, and air exchange rates were measured over four 48‐hour periods when a garage exhaust fan was turned on or off. A blower door test conducted in each garage was used to determine the required exhaust fan flow rate to provide a depressurization of 5 Pa in each garage relative to the home. When corrected for ambient concentrations, the fan decreased geometric mean indoor benzene concentrations from 1.04 to 0.40 μg/m³, or by 62% (P<.05). The garage exhaust fan also significantly reduced outdoor‐corrected geometric mean indoor concentrations of other pollutants, including toluene (53%), ethylbenzene (47%), m,p‐xylene (45%), o‐xylene (43%), and carbon monoxide (23%) (P<.05) while having no impact on the home air exchange rate. This study provides evidence that mechanical exhaust ventilation in attached garages can reduce indoor concentrations of pollutants originating from within attached garages.     

Studies on commuters' exposure to BTEX in passenger cars in Kolkata, India

Commuters' exposure to volatile organic compounds (VOCs) especially BTEX travelling in passenger cars in Kolkata, India were quantified in Phase I (2001-2002) and Phase II (2003-2004). Monitoring was made inside and in the immediate outside of passenger cars fitted with and without catalytic converters using different types of fuels, along two congested urban routes. During Phase I of the study, the benzene content in gasoline was 5% and the mean concentration of in-vehicle benzene in cars without catalytic converter was found to be as high as 721.2 microg/m3. In Phase II when the benzene content was reduced to <3% and with modified engine type, the mean in-vehicle benzene concentration was reduced to 112.4 microg/m3. The in-vehicle concentration varied with engine type and age of the vehicle. Roadside ambient mean concentration of benzene was 214.8 microg/m3 and 30.8 microg/m3 in Phase I and Phase II respectively.     

Contribution of solid fuel, gas combustion, or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes

There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat, or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. Twenty-four-hour data on airborne concentrations of particulate matter<2.5 μm in size (PM2.5), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO2), together with 2-3 week averaged concentrations of nitrogen dioxide (NO2) were collected in 100 houses during the winter and spring of 2009-2010. The geometric mean of the 24-h time-weighted-average (TWA) PM2.5 concentration was highest in homes with resident smokers (99 μg/m3--much higher than the WHO 24-h guidance value of 25 μg/m3). Lower geometric mean 24-h TWA levels were found in homes that burned coal (7 μg/m3) or wood (6 μg/m3) and in homes with gas cookers (7 μg/m3). In peat-burning homes, the average 24-h PM2.5 level recorded was 11 μg/m3. Airborne endotoxin, CO, CO2, and NO2 concentrations were generally within indoor air quality guidance levels. PRACTICAL IMPLICATIONS: Little is known about indoor air quality (IAQ) in homes that burn solid or fossil-derived fuels in economically developed countries. Recent legislative changes have moved to improve IAQ at work and in enclosed public places, but there remains a real need to begin the process of quantifying the health burden that arises from indoor air pollution within domestic environments. This study demonstrates that homes in Scotland and Ireland that burn solid fuels or gas for heating and cooking have concentrations of air pollutants generally within guideline levels. Homes where combustion of cigarettes takes place have much poorer air quality.     

Monitoring of indoor volatile organic compounds and polycyclic aromatic hydrocarbons arising from kerosene cooking fuel.

Air samples, representing indoor environments of a kitchen in which a kerosene stove was used were collected and analysed for volatile organic compounds (VOCs) viz., n-hexane, benzene, heptane, toluene, p- and o-xylene and n-decane using a cryogenic preconcentration system and a gas chromatograph with a flame-ionisation detector. Simultaneous outdoor samples were also collected to determine indoor to outdoor (I/O) ratios for each compound. Reversed phase high performance liquid chromatography (HPLC) with ultra violet absorption detection was optimised for separation and quantification of polycyclic aromatic hydrocarbons (PAHs) in air particulate matter. Concentration of total suspended particulate matter (TSPM), benzene soluble organics and the PAHs in air samples collected in indoor environment of some tenements at Trombay, Mumbai where kerosene is used as cooking fuel are discussed in relation to the concentration of the same in outdoor environment in vicinity of the tenement. VOCs and PAHs results from samples collected in kitchens in Trombay are discussed in relation to indoor air pollution.     

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.     

Indoor air quality in the university libraries of Modena (Italy)

We carried out a survey in 16 libraries of the University of Modena, Northern Italy, to assess the indoor exposure to volatile organic compounds (VOCs), including formaldehyde, and total dusts. Data were collected on the main structural characteristics of the buildings; indoor microclimate parameters, such as temperature, relative humidity and ventilation rate were measured and air samples taken inside and outside the libraries. The mean value of total dusts was 190 +/- 130 microg/m3 with a wide range of values. Formaldehyde was found in only ten out of 16 libraries and the indoor concentrations ranged from 1.70 to 67.8 microg/m3 with an average value of 32.7 +/- 23.9 microg/m3. On the whole, VOCs were present in all the libraries investigated with an average value was 433 +/- 267 microg/m3 (range 102-936 microg/m3). No correlation was found among VOCs, formaldehyde and total dusts nor was a significant association observed with microclimatic parameters or the structural characteristics of the buildings. The general situation found in this study suggests no major problems related to indoor pollution. However, some of the pollutants investigated such as total dust and total VOCs deserve further investigation. It is important to identify the possible sources of contaminants and to define the relationship between indoor and outdoor levels of pollutants more accurately, taking into account the effects of air recycling due to natural ventilation systems.     

Volatile organic compounds in indoor environments in Mumbai, India

Air samples, representing different types of indoor environments, were collected and analyzed for eight hydrocarbons namely, n-hexane, benzene, heptane, toluene, p- and o-xylene, ethyl benzene and n-decane using a cryogenic preconcentration system and a gas chromatograph with a flame-ionization detector. Simultaneous outdoor samples were also collected to determine indoor to outdoor (I/O) ratios for every compound at each location. In all, seven different types of indoor environments were investigated for VOC levels. Toluene concentration levels were found to be high in a hall which was recently renovated. The indoor environment of a kitchen in which a kerosene stove was used and smoker's rooms showed high levels of benzene. The concentrations of VOCs during painting were found to be high and the levels of VOCs depended on the type of paint used. The study revealed that the indoor concentrations of selected VOCs on occasions could be significantly high due to various sources. The data presented here can be useful in developing air quality standards for indoor air.     

Reduction in personal exposures to particulate matter and carbon monoxide as a result of the installation of a Patsari improved cook stove in Michoacan Mexico

The impact of an improved wood burning stove (Patsari) in reducing personal exposures and indoor concentrations of particulate matter (PM(2.5)) and carbon monoxide (CO) was evaluated in 60 homes in a rural community of Michoacan, Mexico. Average PM(2.5) 24-h personal exposure was 0.29 mg/m(3) and mean 48-h kitchen concentration was 1.269 mg/m(3) for participating women using the traditional open fire (fogon). If these concentrations are typical of rural conditions in Mexico, a large fraction of the population is chronically exposed to levels of pollution far higher than ambient concentrations found by the Mexican government to be harmful to human health. Installation of an improved Patsari stove in these homes resulted in 74% reduction in median 48-h PM(2.5) concentrations in kitchens and 35% reduction in median 24-h PM(2.5) personal exposures. Corresponding reductions in CO were 77% and 78% for median 48-h kitchen concentrations and median 24-h personal exposures, respectively. The relationship between reductions in median kitchen concentrations and reductions in median personal exposures not only changed for different pollutants, but also differed between traditional and improved stove type, and by stove adoption category. If these reductions are typical, significant bias in the relationship between reductions in particle concentrations and reductions in health impacts may result, if reductions in kitchen concentrations are used as a proxy for personal exposure reductions when evaluating stove interventions. In addition, personal exposure reductions for CO may not reflect similar reductions for PM(2.5). This implies that PM(2.5) personal exposure measurements should be collected or indoor measurements should be combined with better time-activity estimates, which would more accurately reflect the contributions of indoor concentrations to personal exposures. PRACTICAL IMPLICATIONS: Installation of improved cookstoves may result in significant reductions in indoor concentrations of carbon monoxide and fine particulate matter (PM(2.5)), with concurrent but lower reductions in personal exposures. Significant errors may result if reductions in kitchen concentrations are used as a proxy for personal exposure reductions when evaluating stove interventions in epidemiological investigations. Similarly, time microenvironment activity models in these rural homes do not provide robust estimates of individual exposures due to the large spatial heterogeneity in pollutant concentrations and the lack of resolution of time activity diaries to capture movement through these microenvironments.     

Urban benzene exposure and oxidative DNA damage: influence of genetic polymorphisms in metabolism genes

Benzene has been implicated as an environmental risk factor in leukaemia and other haematological diseases. Relationships between urban benzene exposure, oxidative DNA damage and polymorphisms in metabolism enzymes were examined in 40 volunteers living and working in Copenhagen. Personal exposures to benzene, toluene and methyl tert-butyl ether (MTBE) were monitored during a 5-day period. DNA damage was measured by 7-hydro-8-oxo-2'-deoxyguanosine (8-oxodG) in lymphocyte DNA and urine and by comet assay with use of fapyguanine glycosylase (FPG) and endonuclease III (ENDO). Excretion of the benzene metabolites trans,trans-muconic acid (ttMA) and S-phenylmercapturic acid (S-PMA) were measured in urine. Polymorphisms in glutathione-S-transferases T1 (GSTT1), M1 (GSTM1) and P1 (GSTP1) and NAD(P)H:quinone oxidoreductase (NQO) were determined. Median exposures to benzene, toluene and MTBE were 2.5, 18.7 and 0.86 microg/m(3). No significant correlations between external benzene exposure and any of the biomarkers were found. However, a significant correlation between S-PMA excretion and 8-oxodG in lymphocytes was found (R(s)=0.39). Men were found to excrete significantly more ttMA than the women did and ttMA excretion in men was found to be significantly associated with external benzene exposure (R=0.53, P=0.025). In addition, ttMA and S-PMA excretion was significantly higher in subjects with the NQO+/-genotype compared with subjects with the wild type (P=0.004 and P=0.011, respectively). Even though there are some limitations in this study due to the low range of benzene exposure and biomarker concentrations as well as a small number of subjects, these results could suggest that even at ambient concentrations exposure to benzene could have genotoxic effects in susceptible individuals.