Outdoor Monitoring Research Articles

Experimental characterization of PEM fuel cells by micro-models for the prediction of on-site performance

This paper presents the results of an experimental analysis performed on a miniaturized, 6 W e Proton Exchange Membrane Fuel Cell (PEMFC) system, integrated with on-site hydrogen production by electrolysis; in particular, the effects of environmental parameters such as the external temperature and the humidity on the performance of fuel cells are investigated. PEMFC systems are zero-emissions power technologies when they are fed with pure hydrogen (at concentration higher than 97%); also, being the only results of system operation the produced electricity and some pure water, when produced by renewable sources hydrogen can be considered an attractive alternative to fossil fuels and may concur to the reduction of pollutant and greenhouse gas emissions deriving by combustion processes. A miniaturized, few watts capacity system may represent a safe and unexpensive solution to perform analysis and predict the on-site performance of larger FC applications. The micro-model used for the experimental characterization is a module of a flexible, larger scale system, which is briefly described in the paper; the entire system is equipped with Nafion 112 membranes, two electrolysers, hydrogen storage devices and a Photovoltaic (PV) panel. The results presented in this paper are only a first set of results; others are expected to be obtained in the future by an outdoor monitoring campaign of the entire system, needed to allow an effective prediction of the on-site performance for stand-alone PEMFC systems fed by solar energy. After having simplified the analysis by excluding the parameters that the experimental data revealed to be less influent, at the end of this paper the characterization of the PEMFC system is completed by introducing a semi-empirical model, derived by graphic analyses and data regressions.

Multiple Sclerosis disease distribution and potential impact of environmental air pollutants in Georgia

Multiple Sclerosis (MS) is one of the most common diseases of the central nervous system. Although the disease has been associated with some genetic and environmental factors, it has neither clear causes nor clear temporality with respect to exposure. The purpose of this study was to explore potential relationships between MS and outdoor air pollutants in GA. This study used cross-sectional data from the member's list of the Multiple Sclerosis Society's GA chapter (MSS-GA), the US Census, and a database of county-level Toxic Release Inventory data (emissions across identified, reporting sources to outdoor air, as a surrogate indicator of potential exposure to a criteria pollutant subject to regulation or to chemical toxicants). The final study population was 9,072,576 people, including 6247 self-reported MS cases from MSS-GA. Cases were stratified by gender and transformed into county-level, self-reported prevalence rates using 2005 US Census estimates. County-level prevalence was displayed using a Geographic Information System. Linear regression was conducted to investigate potential relationships between self-reported MS prevalence rates, census data, and environmental outdoor air pollutant indicators. MS prevalence tended to be clustered within the largest metropolitan statistical area (MSA) in Georgia, around Atlanta (Fulton County). The best predictive models for the MS prevalence in GA included both per capita income and PM-10 for females, but only per capita income only for males. The clustering of prevalence of MS in the largest MSA of Georgia, after controlling for population distribution, suggested that urban attributes may be associated with MS. The results of this study further suggested a potential role of PM-10 in the etiology of MS in females, perhaps due to the influence of PM-10 on systemic immune response and inflammation. Based on this initial exploratory study, we recommend more basic and clinical exposure research to understand environmental influences on MS. In particular, outdoor air pollutants like particles, and attached chemicals and metals, which have other known adverse cardiopulmonary health outcomes and are subject to federal and state regulations, could be examined using routinely collected outdoor air monitoring station data and/or modeling.

Evaluation of a direct personal coarse particulate matter monitor

One aspect of the North Carolina Adult Asthma and Environment study (NCAAES) was to evaluate personal exposures to coarse particulate matter (PM 10−2.5) and their associated variability. As part of this, we examined the ability of a community-based monitor to act as a surrogate for an individual's true exposure to this size fraction in linked health effect studies. To assess personal exposures to various particulate matter (PM) size fractions, a personal PM monitor was evaluated. This monitor featured a multi-stage cascade impactor that allowed for the simultaneous collection of PM 10−2.5 and PM 2.5 size fractions. The monitor was evaluated for collocated bias and comparability with a dichotomous (dichot) sampler (device for dividing aerosol PM population into two size fractions during sampling) at an outdoor monitoring site. Results of this evaluation indicated that the prototype was capable of agreement within ±20% of that provided by the reference methodology as well as 20% daily precision for PM 10−2.5 mass measurements.

Urban air pollution, and asthma and COPD hospital emergency room visits

Background:There is little previous information of the effects of size fractioned particulate air pollution and source specific fine particles (PM2.5; <2.5 μm) on asthma and chronic obstructive pulmonary disease (COPD)...

Ambient site, home outdoor and home indoor particulate concentrations as proxies of personal exposures

Despite strong longitudinal associations between particle personal exposures and ambient concentrations, previous studies have found considerable inter-personal variability in these associations. Factors contributing to this inter-personal variability are important to identify in order to improve our ability to assess particulate exposures for individuals. This paper examines whether ambient, home outdoor and home indoor particle concentrations can be used as proxies of corresponding personal exposures. We explore the strength of the associations between personal, home indoor, home outdoor and central outdoor monitoring site ("ambient site") concentrations of sulfate, fine particle mass (PM(2.5)) and elemental carbon (EC) by season and subject for 25 individuals living in the Boston, MA, USA area. Ambient sulfate concentrations accounted for approximately 70 to 80% of the variability in personal and indoor sulfate levels. Correlations between ambient and personal sulfate, however, varied by subject (0.1-1.0), with associations between personal and outdoor sulfate concentrations generally mirroring personal-ambient associations (median subject-specific correlations of 0.8 to 0.9). Ambient sulfate concentrations are good indicators of personal exposures for individuals living in the Boston area, even though their levels may differ from actual personal exposures. The strong associations for sulfate indicate that ambient concentrations and housing characteristics are the driving factors determining personal sulfate exposures. Ambient PM(2.5) and EC concentrations were more weakly associated with corresponding personal and indoor levels, as compared to sulfate. For EC and PM(2.5), local traffic, indoor sources and/or personal activities can significantly weaken associations with ambient concentrations. Infiltration was shown to impact the ability of ambient concentrations to reflect exposures with higher exposures to particles from ambient sources during summer. In contrast in the winter, lower infiltration can result in a greater contribution of indoor sources to PM(2.5) and EC exposures. Placing EC monitors closer to participants' homes may reduce exposure error in epidemiological studies of traffic-related particles, but this reduction in exposure error may be greater in winter than summer. It should be noted that approximately 20% of the EC data were below the field limit of detection, making it difficult to determine if the weaker associations with the central site for EC were merely a result of methodological limitations.

Evaluation of unpleasant odor with a portable electronic nose

An intelligent multi-sensor system with an entire autonomy, a low weight and a small size has been developed for in situ applications such as environmental pollutant gas detection or olfactory estimation. This portable electronic nose works with commercial metal oxide gas sensors and a microcontroller connected to a compact flash memory as intelligent unit. In this work we present the conception of this electronic nose, its laboratory validation, and a real application which concerns an outdoor air monitoring of a duck breeding. This application is developed in order to quantify continuously discomfort odor spread, causing neighbor complaints. The odor measurements were made using our electronic nose (Nepo) and results are compared to the simultaneous results obtained from other olfactometric techniques.

Modeling population exposures to outdoor sources of hazardous air pollutants

Accurate assessment of human exposures is an important part of environmental health effects research. However, most air pollution epidemiology studies rely upon imperfect surrogates of personal exposures, such as information based on available central-site outdoor concentration monitoring or modeling data. In this paper, we examine the limitations of using outdoor concentration predictions instead of modeled personal exposures for over 30 gaseous and particulate hazardous air pollutants (HAPs) in the US. The analysis uses the results from an air quality dispersion model (the ASPEN or Assessment System for Population Exposure Nationwide model) and an inhalation exposure model (the HAPEM or Hazardous Air Pollutant Exposure Model, Version 5), applied by the US. Environmental protection Agency during the 1999 National Air Toxic Assessment (NATA) in the US. Our results show that the total predicted chronic exposure concentrations of outdoor HAPs from all sources are lower than the modeled ambient concentrations by about 20% on average for most gaseous HAPs and by about 60% on average for most particulate HAPs (mainly, due to the exclusion of indoor sources from our modeling analysis and lower infiltration of particles indoors). On the other hand, the HAPEM/ASPEN concentration ratio averages for onroad mobile source exposures were found to be greater than 1 (around 1.20) for most mobile-source related HAPs (e.g. 1, 3-butadiene, acetaldehyde, benzene, formaldehyde) reflecting the importance of near-roadway and commuting environments on personal exposures to HAPs. The distribution of the ratios of personal to ambient concentrations was found to be skewed for a number of the VOCs and reactive HAPs associated with major source emissions, indicating the importance of personal mobility factors. We conclude that the increase in personal exposures from the corresponding predicted ambient levels tends to occur near locations where there are either major emission sources of HAPs or when individuals are exposed to either on- or nonroad sources of HAPs during their daily activities. These findings underscore the importance of applying exposure-modeling methods, which incorporate information on time-activity, commuting, and exposure factors data, for the purposes of assigning exposures in air pollution health studies.

Increasing Prevalence of Atopic Eczema in Taiwanese Adolescents From 1995 to 2001

ISEE-18 Objective: The prevalence of atopic eczema in adolescents has recently been reported as increasing in many countries, a phenomenon yet to be fully explained. This study compared the prevalence of atopic eczema among Taiwanese adolescents with individual-level risk factors and community-level data of temperature, relative humidity, and air pollutants to determine whether changes in these factors could explain the observed change in prevalence. Material and Methods: We conducted 2 nationwide, cross-sectional surveys of atopic illness and symptoms among 12- to 15-year-old Taiwanese schoolchildren in 1995 to 1996 and 2001. The effects of personal and environmental factors were assessed and temporal changes of outdoor monitoring data were also compared with prevalence difference of atopic eczema. Results: A total of 42,919 adolescents from the 1995 to1996 survey and 10,215 adolescents from the 2001 survey attended schools located within 1 km of 22 monitoring stations. The 12-month prevalence of atopic eczema increased significantly during this period [adjusted prevalence ratio (PR) = 1.43, 95% confidence interval (CI) 1.21–1.70 in boys; PR = 1.77, 95% CI 1.49–2.10 in girls]. After adjustment for potential risk factors, the prevalence differences were statistically unchanged. Although parental education level contributed the most, changes in personal and environmental factors might not explain the observed prevalence increases of atopic eczema. Temporal change in relative humidity was significantly associated with prevalence increase among boys but its contribution was also small. Conclusions: Correlates of the investigated risk factors that have changed over time still underlie the prevalence increases of atopic eczema in Taiwanese adolescents. The exact reasons for the rising trends remain to be elucidated.

Coverage-time optimized dynamic clustering of networked sensors for pervasive home networking

This paper proposes a novel energy-efficient coverage-time optimized dynamic clustering scheme for two- tiered wireless sensor networks (WSNs) used in an outdoor monitoring application of home networking systems. The coverage-time is defined as the time until one of cluster heads (CHs) runs out of energy in clustering-based WSNs, thereby resulting in an incomplete coverage. DC-CTO scheme regulates cluster radii for balanced energy consumption among CHs to maximize coverage-time. There are several advantages of using the DC-CTO scheme. The first advantage is balanced energy consumption among CHs under NLP- based computations. The second advantage is minimized energy consumption in each CH to extend coverage-time. The last one is the guarantee of perfect coverage. If there is no area which is uncontrolled by a CH in a networked sensing field, we call it a perfect coverage. If there is an incomplete coverage, the event in the area cannot be identified. Therefore perfect coverage is important to robust monitoring systems. The novelty of DC-CTO scheme is demonstrated by various simulation-based performance evaluations.

Increasing prevalence of atopic eczema in Taiwanese adolescents from 1995 to 2001

The prevalence of atopic eczema in adolescents has recently been reported as increasing in many countries, a phenomenon yet to be fully explained. This study compared the prevalence of atopic eczema among Taiwanese adolescents with individual-level risk factors and community-level data of temperature, relative humidity, and air pollutants to determine whether changes in these factors could explain the observed change in prevalence. We conducted two nationwide, cross-sectional surveys of atopic illness and symptoms among Taiwanese 12-15-year-old schoolchildren in 1995-1996 and 2001. The effects of personal and environmental factors were assessed and temporal changes of outdoor monitoring data were also compared with the prevalence difference of atopic eczema. A total of 42 919 adolescents from the 1995 to 1996 survey and 10 215 adolescents from the 2001 survey attended schools located within 1 km of 22 monitoring stations. The 12-month prevalence of atopic eczema increased significantly during this period [adjusted prevalence ratio (PR)=1.43, 95% confidence interval (CI) 1.21-1.70 in boys; PR=1.77, 95% CI 1.49-2.10 in girls]. After adjustment for potential risk factors, the prevalence differences were statistically unchanged. Although parental education level contributed the most, changes in personal and environmental factors might not explain the observed prevalence increases of atopic eczema. Temporal change in the relative humidity was significantly associated with prevalence increase among boys but its contribution was also small. Correlates of the investigated risk factors that have changed over time still underlie the prevalence increases of atopic eczema in Taiwanese adolescents. The exact reasons for the rising trends remain to be elucidated.

Associations of Fine and Ultrafine Particulate Air Pollution With Stroke Mortality in an Area of Low Air Pollution Levels

Daily variation in outdoor concentrations of inhalable particles (PM(10) <10 microm in diameter) has been associated with fatal and nonfatal stroke. Toxicological and epidemiological studies suggest that smaller, combustion-related particles are especially harmful. We therefore evaluated the effects of several particle measures including, for the first time to our knowledge, ultrafine particles (<0.1 microm) on stroke. Levels of particulate and gaseous air pollution were measured in 1998 to 2004 at central outdoor monitoring sites in Helsinki. Associations between daily levels of air pollutants and deaths caused by stroke among persons aged 65 years or older were evaluated in warm and cold seasons using Poisson regression. There was a total of 1304 and 1961 deaths from stroke in warm and cold seasons, respectively. During the warm season, there were positive associations of stroke mortality with current- and previous-day levels of fine particles (<2.5 microm, PM(2.5)) (6.9%; 95% CI, 0.8% to 13.8%; and 7.4%; 95% CI, 1.3% to 13.8% for an interquartile increase in PM(2.5)) and previous-day levels of ultrafine particles (8.5%; 95% CI, -1.2% to 19.1%) and carbon monoxide (8.3; 95% CI, 0.6 to 16.6). Associations for fine particles were mostly independent of other pollutants. There were no associations in the cold season. Our results suggest that especially PM(2.5), but also ultrafine particles and carbon monoxide, are associated with increased risk of fatal stroke, but only during the warm season. The effect of season might be attributable to seasonal differences in exposure or air pollution mixture.

Application of the personal aeroallergen sampler to assess personal exposures to Japanese cedar and cypress pollens

We have recently developed the Personal Aeroallergen Sampler (PAAS), a passive sampler for aeroallergens. In the present study, the applicability of the PAAS for personal exposure assessments of cedar and cypress pollens was investigated by comparing with existing reference samplers. To investigate the usability of the PAAS as a personal sampler for the airborne pollens, it was compared with the Institute of Occupational Medicine (IOM) sampler, a traditionally used active personal sampler. Overall, the result showed a good correlation between the two methods, that is, R(2)=0.8082, suggesting the usability of the PAAS for the personal pollen samplings. The ratio of the pollen numbers collected by the PAAS to the IOM sampler was approximately 30%, which was consistent with our previous study investigating ambient dust particles. Meanwhile, the comparability of the PAAS to the Durham sampler, the most widely used stationary pollen trap, was also assured. Furthermore, we exemplified the seasonal peak of the personal pollen exposures was not necessarily reflected by the outdoor concentrations, indicating insufficiency of the stationary outdoor monitoring to represent the personal pollen exposures. The PAAS, a simple passive method, could be used in future field studies to elucidate the detailed mechanisms of allergic airway diseases such as cedar pollinosis.

Long-term personal exposure to PM 2.5, soot and NO x in children attending schools located near busy roads, a validation study

Several studies have investigated the health of children attending schools located near busy roads. In this study, we have measured personal exposure to traffic-related pollutants in children to validate exposure classification based on school location. Personal exposure to PM 2.5, soot, NO x and NO 2 was measured during four 48-h periods. The study involved 54 children attending four different schools, two of which were located within 100 m of a major road (one ring road and one freeway) and the other two were located at a background location in the city of Utrecht, The Netherlands. Outdoor monitoring was conducted at all school sites, during the personal measurements. A questionnaire was administered on time activity patterns and indoor sources at home. The outdoor concentration of soot was 74% higher at the freeway school compared to its matched background school. Personal exposure to soot was 30% higher. For NO x the outdoor concentration was 52% higher at the freeway school compared to its background school. The personal concentration of NO x was 37% higher for children attending the freeway school. Differences were smaller and insignificant for PM 2.5 and NO 2. No elevated personal exposure to air pollutants was found for the children attending the school near the ring road. We conclude that the school's proximity to a freeway can be used as a valid estimate of exposure in epidemiological studies on the effects of the traffic-related air pollutants soot and NO x in children.

Levels of outdoor PM 2.5, absorbance and sulphur as surrogates for personal exposures among post-myocardial infarction patients in Barcelona, Spain

Outdoor levels of fine particles (PM 2.5; particles <2.5 μm) have been associated with cardiovascular health. Persons with existing cardiovascular disease have been suggested to be especially vulnerable. It is unclear, how well outdoor concentrations of PM 2.5 and its constituents measured at a central site reflect personal exposures in Southern European countries. The objective of the study was to assess the relationship between outdoor and personal concentrations of PM 2.5, absorbance and sulphur among post-myocardial infarction patients in Barcelona, Spain. Thirty-eight subjects carried personal PM 2.5 monitors for 24-h once a month (2–6 repeated measurements) between November 2003 and June 2004. PM 2.5 was measured also at a central outdoor monitoring site. Light absorbance (a proxy for elemental carbon) and sulphur content of filter samples were determined as markers of combustion originating and long-range transported PM 2.5, respectively. There were 110, 162 and 88 measurements of PM 2.5, absorbance and sulphur, respectively. Levels of outdoor PM 2.5 (median 17 μg m 3) were lower than personal PM 2.5 even after excluding days with exposure to environmental tobacco smoke (ETS) (median after exclusion 27 μg m 3). However, outdoor concentrations of absorbance and sulphur were similar to personal concentrations after exclusion of ETS. When repeated measurements were taken into account, there was a statistically significant association between personal and outdoor absorbance when adjusting for ETS (slope 0.66, p<0.001), but for PM 2.5 the association was weaker (slope 0.51, p=0.066). Adjustment for ETS had little effect on the respective association of S (slope 0.69, p<0.001). Our results suggest that outdoor measurements of absorbance and sulphur can be used to estimate both the daily variation and levels of personal exposures also in Southern European countries, especially when exposure to ETS has been taken into account. For PM 2.5, indoor sources need to be carefully considered.

Coarse particulate matter concentrations from residential outdoor sites associated with the North Carolina Asthma and Children's Environment Studies (NC-ACES)

Coarse particulate matter (PM 10 - 2.5 ) concentration data from residential outdoor sites were collected using portable samplers as part of an exposure assessment for the North Carolina Asthma and Children's Environment Studies (NC-ACES). PM 10 - 2.5 values were estimated using the differential between independent PM 10 and PM 2.5 collocated MiniVol measurements. Repeated daily 24-h integrated PM 10 and PM 2.5 residential outdoor monitoring was performed at a total of 26 homes during September 2003–June 2004 in the Research Triangle Park, NC area. This effort resulted in the collection of 73 total daily measurements. This assessment was conducted to provide data needed to investigate the association of exposures to coarse particle PM mass concentrations with observed human health effects. Potential instrument bias between the differential MiniVol methodology and a dichotomous sampler were investigated. Results indicated that minimal bias of PM 10 - 2.5 mass concentration estimates (slope = 0.8, intercept = 0.36 μ g m - 3 ) existed between the dichotomous and differential MiniVol procedures. Residential outdoor PM 10 - 2.5 mass concentrations were observed to be highly variable across measurement days and ranged from 1.1 to 12.6 μ g m - 3 (mean of 5.4 μ g m - 3 ) . An average correlation coefficient of r = 0.75 existed between residential outdoor PM 10 - 2.5 mass concentrations and those obtained from the central ambient monitoring site. Temporal and spatial variability of PM 10 - 2.5 mass concentrations during the study were observed and are described in this report.

Conducting The First Randomized Control Trial of Acute Lower Respiratory Infections and Indoor Air Pollution: Description of Process and Methods

MS3 Symposium Title: RESPIRE—The Guatemala Randomized Intervention Trial. Symposium Organizers: Kirk R. Smith, Nigel Bruce, and Byron Arana. MS3-01 Objectives: The objectives of this study were to site and conduct a randomized, controlled trial (RCT) to examine the improvement in child acute lower respiratory infection (ALRI) by introduction of a chimney stove designed to reduce indoor exposures to biomass smoke in a rural developing country setting. Background: After unsuccessful efforts in the 1980s to fund the RCT in Nepal, an international committee was established by WHO, Geneva, in 1991 to locate the best site for the RCT. Based on criteria related to local health, exposure, logistics, and institutional conditions, a dozen sites were examined in Asia, Africa, and Latin America. Highland Guatemala was chosen and a range of pilot studies undertaken in the 1990s to develop the data needed to design and successfully fund the RCT, which began in 2001. Setting: The chosen site is home to a largely indigenous primarily agricultural Mayan population living at 2700 to 3000 m in the western Guatemalan highlands. Most of the population speaks a local language, Mam, with Spanish as a second language for many. Nearly all households in the area use only wood for all household fuel requirements. Preintervention ALRI rates in young children were estimated at 0.5 per child-year. Methods: A rapid assessment was undertaken among 5500 households in the area to screen for recruitment based on use of an open fire for cooking, presence of a pregnant women or child under 4 months, migration patterns, and willingness to participate. To meet statistical goals (two-sided α = 0.05, power = 0.80, 25% effect), 534 households were eventually recruited, 518 (97%) of which contributed to the final dataset. After baseline household and indoor air quality (IAQ) surveys, households were randomly assigned to receive an improved chimney stove, the plancha, at the start of the study or at the end, when the study child reached 18 months, or a household dropped out. Pilot work showed that planchas were popular, sturdy, and capable of substantially improving kitchen IAQ. After stove installation, weekly household visits were conducted by trained fieldworkers to identify potentially ill children, who were then referred to study physicians (see companion abstract for details). Planchas were repaired by the study when structural problems appeared. Anthropometry was conducted regularly and birth weights recorded within 48 hours after delivery. Verbal autopsies were conducted on all child deaths. Quarterly personal 48-hour CO exposures were obtained for all study children and mothers. Intensive IAQ monitoring for CO and PM was conducted in a 13% subsample along with outdoor monitoring and assessment of exposures from use of wood-fired saunas (temascals). Results: The 518 children followed contributed nearly 600 child-years of surveillance. Randomization was successful because there were no significant differences between the 2 groups for any of the dozens of household, demographic, and social variables examined, except for leaks in the roof. At 8%, the dropout rate was within the 20% projected in sample-size calculations and was due primarily to migration (50%) from the area. There was a slightly higher dropout rate (9.3% P = 0.39) for intervention households. Discussion: Although not easily quantified, absolutely essential for successful implementation were the hospitality and cooperative spirit of the local communities and the field workers recruited from them.Table

Indoor Air Pollution Assessment and Cookstove Quality in Two Honduran Communities

P-294 Introduction: Elevated indoor air pollution (IAP) exposures associated with the burning of biomass fuels in developing countries are well established. Improved cookstoves have the potential to substantially reduce these exposures. Previous studies have relied mostly on crude proxies of exposure, such as type of stove or fuel. However, several studies have demonstrated the value of estimating IAP exposures by evaluating personal cooking practices and household parameters in addition to fuel and stove quality. This study will assess these factors and a scale of stove quality in relation to quantitative personal and indoor air quality measures. Methods: We conducted a cross-sectional survey among 60 non-smoking women in two communities, one semi-urban and one rural. Thirty women cooked with traditional stoves and 30 with improved stoves with chimneys. Carbon monoxide (CO) and particulate matter (PM2.5) were assessed via 8-hour indoor and outdoor monitoring, as well as 8-hour personal PM2.5 monitoring. Kitchen volume, building materials, presence and size of eaves spaces and windows, carbon dioxide, temperature, and relative humidity were determined to estimate ventilation rates that may affect CO and PM2.5 levels. Personal cooking practices were assessed. Stove quality was assessed using a 4-level subjective scale representing potential for indoor emissions, ranging from poorly functioning traditional stoves to well-functioning improved stoves. Multivariate linear regression analyses will be used to determine which combination of parameters (including stove quality, personal cooking habits, and factors affecting ventilation rates) most accurately predicts personal and indoor air quality measurements. Results: Personal PM2.5 means were 198 and 74 μg/m3 for traditional stove users and improved stove users, respectively. Indoor PM2.5 and CO means were also higher among traditional stove users. Personal PM2.5 means corresponding to the subjective stove scale were 236, 119, 82, and 66 μg/m3, respectively. Corresponding indoor PM2.5 means were 1258, 532, 294, and 218 μg/m3, respectively; indoor CO means were 9.18, 3.29, 1.30, and 0.16 ppm, respectively. Personal PM2.5 means were moderately correlated with indoor PM2.5 means (r=0.61) but less so with outdoor PM2.5 means (r=0.38). Results from regression models examining the association of stove quality, personal cooking habits, and factors affecting ventilation rates with personal and indoor air quality measures will be presented. Discussion: The varying levels of indoor pollution measured in homes with improved stoves support the use of a multi-level stove scale. These results could provide a cost-effective alternative to air quality monitoring for large-scale epidemiologic investigations of IAP and adverse health endpoints.

Real-time outdoor video surveillance with robust foreground extraction and object tracking via multi-state transition management

In this paper we present an effective and flexible real-time video analysis system aiming at a wide range of outdoor surveillance and monitoring scenarios, in which robust detection and tracking ob...

Levels of Outdoor PM2.5 and Absorbance as Surrogates for Personal Exposures Among Post-Myocardial Infarction Patients

TAA3-O-02 Introduction: Outdoor levels of fine particles (PM2.5; particles <2.5 μm) have been associated with cardiovascular health in epidemiologic studies. Persons with existing cardiovascular disease have been suggested to be especially vulnerable. The use of outdoor concentrations to estimate personal exposures has been questioned in this population group due to their less active lifestyle. The objective of the study was to assess the relationship between outdoor and personal PM2.5 and absorbance, indicator for combustion originating PM2.5, among subjects with cardiovascular disease. Methods: The study was conducted in a Mediterranean city between November 2003 and June 2004 within a larger epidemiologic study. Post-myocardial infarction patients visited a clinic for health examination every 4th week. They carried personal PM2.5 monitors for 24 hours before every visit. At the same time, PM2.5 was measured at a fixed outdoor monitoring site. Absorbance of all PM2.5 filter samples was measured as a marker for elemental carbon. Results: There were 36 patients (83% males, average age 61 years) with 2 to 6 measurements, and 105 valid samples. Levels of outdoor PM2.5 (median = 16.97 μg/m3) were lower than personal concentrations (median 34.1 μg/m3), even after excluding days with exposure to environmental tobacco smoke (ETS) (n = 44, median after exclusion 28.2 μg/m3). However, outdoor absorbance (median 4 m−1/105) was similar to personal absorbance (median 2.9 m−1/105) after exclusion of ETS. Outdoor and personal PM2.5 were not correlated cross-sectionally, whereas outdoor absorbance was correlated with exposure (r = 0.41), especially after excluding days with ETS (r = 0.77). In mixed models, where the repetitive nature of the measurements was taken into account, there was a statistically significant association between personal and outdoor absorbance when adjusting for ETS (slope 0.72, P < 0.001), but for PM2.5 the association was weaker (slope 0.57, P = 0.074). Discussion and Conclusions: Outdoor measurements of PM2.5 absorbance, a proxy for combustion originating fraction of PM2.5, estimate well both the variation and levels of personal exposure when exposure to ETS has been taken into account. For PM2.5 there are more indoor and personal sources to consider.

Associations of Fine and Ultrafine Particulate Air Pollution with Specified Cardiovascular Causes of Death

P-030 Background: Particulate air pollution has been associated with cardiovascular mortality. Toxicological and epidemiological studies suggest that the smallest particles are especially harmful. However, there is a lack of long, continuous measurement series of finer particle fractions, especially ultrafine particles (<0.1 μm). We have daily data on ultrafine particle concentrations since 1998. Therefore, we examined the associations of daily levels of ultrafine and fine (<2.5 μm) particles with cause-specific cardiovascular mortality. Methods: Ultrafine particle number concentrations were monitored with a differential mobility particle sizer in 1998–2002 at a central outdoor monitoring site. Deaths due to all cardiovascular diseases (ICD-10: I00-I99; N=13 839), stroke (I60-I61, I63-I64; N=2783), ischemic heart diseases (I20-I25; N=8014) and other heart diseases (I30-I51; N=1167) were analyzed separately. The associations between daily levels of air pollution and deaths were evaluated using Poisson regression and controlling for time trend, temperature, relative humidity, barometric pressure, weekday and general holidays. Results: The median concentration for ultrafine particles was 9700 1/cm3 and for PM2.5 8.5 μg/m3. We found no consistent associations between ultrafine particles and mortality. There was some evidence of a positive association between fine particles and ‘other’ heart diseases with 4.15% (95% CI,1.3–9.9) increase in mortality for an interquartile increase in PM2.5 at lag 1. Conclusions: We found no strong associations between particulate air pollution and cardiovascular mortality when analyzing all seasons together. Based on our earlier experience on respiratory mortality, additional analyzes will be performed by warm and cold season separately.