Personal Carbon Monoxide Exposure Research Articles

Household air pollution and risk of pulmonary tuberculosis in HIV-Infected adults

BackgroundIn low- and middle-income countries countries, millions of deaths occur annually from household air pollution (HAP), pulmonary tuberculosis (PTB), and HIV-infection. However, it is unknown whether HAP influences PTB risk among people living with HIV-infection.MethodsWe conducted a case-control study among 1,277 HIV-infected adults in Bukavu, eastern Democratic Republic of Congo (February 2018 – March 2019). Cases had current or recent (<5y) PTB (positive sputum smear or Xpert MTB/RIF), controls had no PTB. Daily and lifetime HAP exposure were assessed by questionnaire and, in a random sub-sample (n=270), by 24-hour measurements of personal carbon monoxide (CO) at home. We used multivariable logistic regression to examine the associations between HAP and PTB.ResultsWe recruited 435 cases and 842 controls (median age 41 years, [IQR] 33-50; 76% female). Cases were more likely to be female than male (63% vs 37%). Participants reporting cooking for >3h/day and ≥2 times/day and ≥5 days/week were more likely to have PTB (aOR 1·36; 95%CI 1·06-1·75) than those spending less time in the kitchen. Time-weighted average 24h personal CO exposure was related dose-dependently with the likelihood of having PTB, with aOR 4·64 (95%CI 1·1-20·7) for the highest quintile [12·3-76·2 ppm] compared to the lowest quintile [0·1-1·9 ppm].ConclusionTime spent cooking and personal CO exposure were independently associated with increased risk of PTB among people living with HIV. Considering the high burden of TB-HIV coinfection in the region, effective interventions are required to decrease HAP exposure caused by cooking with biomass among people living with HIV, especially women.

Characterization of occupational smoke exposure among wildland firefighters in the midwestern United States

Wildland firefighters are repeatedly exposed to elevated levels of wildland fire smoke (WFS) while protecting lives and properties from wildland fires. Studies reporting personal exposure concentrations of air pollutants in WFS during fire suppression or prescribed burn activities have been geographically limited to the western and southeastern United States. The objective of this study is to characterize exposure concentrations of air pollutants in WFS emissions among wildland firefighters who conducted prescribed burns in the Midwest. Between 2016 and 2019, a total of 35 firefighters (31 males and 4 females, age of 35.63 ± 9.31 years) were recruited to participate in this study. Personal particulate matter 2.5 (PM2.5) and carbon monoxide (CO) exposure concentrations were measured during prescribed burns. The level of black carbon (BC) in WFS particulates was determined using the light transmission technique, while trace metal composition was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The results showed geometric means for PM2.5, CO, and BC concentrations were 1.43 ± 0.13 mg/m3, 7.02 ± 0.69 ppm, and 58.79 ± 5.46 μg/m3, respectively. Although no occupational exposure limits (OELs) were exceeded by 8-h time-weighted average (TWA) exposure concentration observed in the firefighters, a total of 28 personal CO exposure concentrations were above the National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) Ceiling (200 ppm) for CO. PM2.5 and CO concentrations were about 2–7 times higher in the Midwest than the other regions. Firefighters who performed holding had higher CO exposure concentrations compared to firefighters who performed lighting (p < 0.01), while lighters were exposed to higher level of BC in the smoke particulates (p < 0.01), possibly due to the domination of exposure by different combustion sources and stages. The levels of trace metals in WFS particulates were well below the corresponding OELs and no task-related difference was observed except for manganese. Our results suggest that wildland firefighters in the midwestern region have higher WFS exposures while working at prescribed burns compared to those western and southeastern United States.

Personal carbon monoxide exposure, respiratory symptoms, and the potentially modifying roles of sex and HIV infection in rural Uganda: a cohort study

BackgroundMost of the global burden of pollution-related morbidity and mortality is believed to occur in resource-limited settings, where HIV serostatus and sex may influence the relationship between air pollution exposure and respiratory morbidity. The lack of air quality monitoring networks in these settings limits progress in measuring global disparities in pollution-related health. Personal carbon monoxide monitoring may identify sub-populations at heightened risk for air pollution-associated respiratory morbidity in regions of the world where the financial cost of air quality monitoring networks is prohibitive.MethodsFrom September 2015 through May 2017, we measured 48-h ambulatory carbon monoxide (CO) exposure in a longitudinal cohort of HIV-infected and uninfected adults in rural southwestern Uganda. We fit generalized mixed effects models to identify correlates of CO exposure exceeding international air quality thresholds, quantify the relationship between CO exposure and respiratory symptoms, and explore potential effect modification by sex and HIV serostatus.ResultsTwo hundred and sixty study participants completed 419 sampling periods. Personal CO exposure exceeded international thresholds for 50 (19%) participants. In covariate-adjusted models, living in a home where charcoal was the main cooking fuel was associated with CO exposure exceeding international thresholds (adjusted odds ratio [AOR] 11.3, 95% confidence interval [95%CI] 4.7–27.4). In sex-stratified models, higher CO exposure was associated with increased odds of respiratory symptoms among women (AOR 3.3, 95%CI 1.1–10.0) but not men (AOR 1.3, 95%CI 0.4–4.4). In HIV-stratified models, higher CO exposure was associated with increased odds of respiratory symptoms among HIV-infected (AOR 2.5, 95%CI 1.01–6.0) but not HIV-uninfected (AOR 1.4, 95%CI 0.1–14.4) participants.ConclusionsIn a cohort in rural Uganda, personal CO exposure frequently exceeded international thresholds, correlated with biomass exposure, and was associated with respiratory symptoms among women and people living with HIV. Our results provide support for the use of ambulatory CO monitoring as a low-cost, feasible method to identify subgroups with heightened vulnerability to pollution-related respiratory morbidity in resource-limited settings and identify subgroups that may have increased susceptibility to pollution-associated respiratory morbidity.

Ambulatory monitoring demonstrates an acute association between cookstove-related carbon monoxide and blood pressure in a Ghanaian cohort

BackgroundRepeated exposure to household air pollution may intermittently raise blood pressure (BP) and affect cardiovascular outcomes. We investigated whether hourly carbon monoxide (CO) exposures were associated with acute increases in ambulatory blood pressure (ABP); and secondarily, if switching to an improved cookstove was associated with BP changes. We also evaluated the feasibility of using 24-h ambulatory blood pressure monitoring (ABPM) in a cohort of pregnant women in Ghana.MethodsParticipants were 44 women enrolled in the Ghana Randomized Air Pollution and Health Study (GRAPHS). For 27 of the women, BP was measured using 24-h ABPM; home blood pressure monitoring (HBPM) was used to measure BP in the remaining 17 women. Personal CO exposure monitoring was conducted alongside the BP monitoring.ResultsABPM revealed that peak CO exposure (defined as ≥4.1 ppm) in the 2 hours prior to BP measurement was associated with elevations in hourly systolic BP (4.3 mmHg [95% CI: 1.1, 7.4]) and diastolic BP (4.5 mmHg [95% CI: 1.9, 7.2]), as compared to BP following lower CO exposures. Women receiving improved cookstoves had lower post-intervention SBP (within-subject change in SBP of −2.1 mmHg [95% CI: -6.6, 2.4] as compared to control), though this result did not reach statistical significance. 98.1% of expected 24-h ABPM sessions were successfully completed, with 92.5% of them valid according to internationally defined criteria.ConclusionsWe demonstrate an association between acute exposure to carbon monoxide and transient increases in BP in a West African setting. ABPM shows promise as an outcome measure for assessing cardiovascular health benefits of cookstove interventions.Trial registrationThe GRAPHS trial was registered with clinicaltrials.gov on 13 April 2011 with the identifier NCT01335490.

Household air pollution following replacement of traditional open fire with an improved rocket type cookstove.

Cooking with biomass fuel is an important source of household air pollution (HAP) in developing countries, and a leading risk factor for ill-health. Although various designs of "improved cookstoves" (ICS) have been promoted as HAP interventions in these settings, few of them have undergone in-field evaluation, partly due to the challenge of conducting field measurements in remote settings. In this study we assessed the change in carbon monoxide (CO) exposure following the replacement of the traditional three-stone stove with a popular ICS in 49 homes in Western Kenya. We also assessed the suitability of using kitchen CO as a proxy for kitchen PM2.5. Reduction in 48h mean kitchen CO was 3.1ppm (95% CI: -8.1, 1.8) and in personal CO was 0.9ppm (95% CI: -4.3, 2.6) following stove replacements. Overall, 48-h kitchen and personal CO exposures were lower after stove replacement (28% and 12%, respectively) but with wide confidence intervals that also suggested possible increases in exposure. There were statistically significant reductions in peak kitchen and personal CO concentrations represented by the 8-h 95th percentile: reductions of 26.1ppm (95% CI: -44.6, -7.6) and 8.0ppm (95% CI: -12.2, -3.8), respectively. This is equivalent to 53% reduction in kitchen CO and 39% reduction in personal CO. We found good correlation between kitchen CO and PM2.5 concentrations overall (r=0.73, n=33 over averaging periods approximating 1day), which varied by time of day and exposure setting. These variations limit the applicability of CO as a proxy measure for PM2.5 concentrations. A combination of interventions, including better designed stoves, improved ventilation and cleaner fuels, may be needed to reduce HAP to levels that are likely to improve health.

Personal carbon monoxide exposures ability to predict fine particulate matter exposure in the Ghana Randomized Air Pollution and Helath Study (GRAPHS)

Introduction: Prenatal exposure to household air pollution has been implicated as a risk factor for adverse birth outcomes. There are limited data on personal exposure for pregnant women that use b...

Influence of Differing Microenvironments on Personal Carbon Monoxide Exposure in Auckland, New Zealand

Epidemiological studies typically estimate pollutant exposures using data from outdoor fixed monitoring stations (FMS). However, due to individual mobility through space, time spent in indoor environments and the heterogeneity of the urban atmosphere, data from FMS provides a poor representation of the actual personal exposure to air pollutants. The aim of this study is to investigate the relative importance of time spent in common microenvironments (such as commuter, home, work and recreational) to determine personal exposure to air pollution. The study also investigates the extent to which fixed monitoring stations (FMS) are representative of personal exposures. For this purpose, 17 participants monitored their personal exposure to carbon monoxide (CO) for a full working week and completed a time activity diary identifying the particular microenvironments in which they spent their time. Overall, the participants exposure to CO were lower than those observed in other northern hemisphere cities reported upon in the literature. FMS located in central Auckland were found to provide reasonable estimates of mean daily personal exposure but were poorly correlated with diurnal variations in personal exposure. The results found that, while the highest mean exposures were recorded in the commuter microenvironment, the home microenvironment accounted for 55% of the total CO dose during the week. Increased levels of personal CO exposure were observed in indoor areas where gas heating, gas stoves and tobacco smoke were present. Participants recorded highly variable exposure to CO in recreational microenvironments, in part explained by the wide range of recreational activities.

Indoor PM and CO concentrations in rural Guizhou, China

Household air pollution (HAP) from use of solid fuels varies greatly depending on stove technology, fuel, housing characteristics, season, and geographical area. Accurate information about indoor air pollution concentration as well as personal exposure is vital for more precise estimates of the health burden from HAP. We measured indoor fine particles ≤2.5μm in aerodynamic diameter (PM2.5) and carbon monoxide (CO) concentrations for 48h in 179 homes in winter and 122 homes in summer in rural Guizhou, China. Furthermore, we measured personal CO exposure among 1796 women. The highest median [25th–75th percentiles] PM2.5 kitchen concentrations were found in winter in biomass homes with an open fire (557 [303–882] μg/m3) or a stove without chimney (533 [210–770] μg/m3), while homes with a chimney stove had lower median kitchen concentrations (337 [212–1114] μg/m3 and 371 [192–1208] μg/m3 for biomass and coal, respectively). There was large seasonal variability with lower concentrations in summer for both PM2.5 and CO. Indoor CO concentrations were more correlated with type of fuel than stove technology, with higher median winter concentrations in kitchens using biomass (2.4 [0.9–4.6] ppm) than coal (0.7 [0.6–1.5] ppm). Personal CO exposure was relatively low, with median 1.3 [0.9–2.1] ppm. Stove and fuel type, ventilation, kitchen configuration, occupation, secondhand tobacco smoke, time spent outdoors, and ambient temperature were all associated with personal CO exposure. We found that CO could not be used as a suitable proxy for PM2.5 in this setting due to large heterogeneity in stove and fuel use within homes. We also found only a weak correlation between personal and indoor measurements, highlighting the importance of doing personal measurements in epidemiological research. Most households exceeded the PM10 Chinese indoor air pollution standard of 150μg/m3. Hence, continued efforts are needed to mitigate health damaging levels of HAP.

Evaluating the impacts of an advanced stove intervention on traditional cooking patterns and pollutant exposures in India using Stove Use Monitors

Background/Aims. Household air pollution in 2010 was responsible for ~3.5 million premature deaths and 500,000 through contributions to outdoor air pollution. 900,000 of these deaths occurred in India, where ~66% of households rely on wood, dung, or crop residues as their primary cooking fuels. Since alternative fuels are unlikely to become available soon, cleaner ways of using these fuels need evaluation. Methods. Beginning in 2012 as part of ongoing work at the SOMAARTH surveillance area in Palwal district, Haryana, we distributed 200 forced-draft ('advanced') biomass stoves to pregnant women. These stoves have low laboratory emissions and good field evaluations. Using Stove Use Monitors (SUMs), portable data-logging thermometers, we monitored usage of traditional and intervention stoves. This revealed how use patterns changed after advanced stove introduction. In a subset of homes, we monitored PM2.5 and carbon monoxide (CO) in kitchens and personal CO exposures of participants. SUMs were placed on traditional stoves up to 2 weeks before SUMs-equipped advanced stove dissemination. Prior to and following advanced stove distribution, pollutant concentrations were assessed over 48-hour periods in a subset of homes. SUMs logged temperatures every 10 minutes and were downloaded twice monthly. Nearly 400 stoves continue to be monitored, yielding over 110,000 stove-days of data. Results/ Conclusions. Personal CO exposures decreased post intervention from 10.9 ppm to 4.8 ppm. Area PM and CO concentrations by 59.8% and 55.9% respectively. Prior to the intervention, households used traditional stoves twice daily on average - consistent with previous findings. A small proportion of households used advanced stoves only. The majority used both stoves, a phenomenon termed "stacking," which has profound implications for intervention strategies, as traditional stoves dominate household emissions and drive personal exposures. Mixed effects models were used to evaluate the contribution of stove type and household characteristics to area concentrations and personal exposures.

Looking back to move forward: Lessons learned from the RESPIRE trial applied to the NACER study

Background: Few studies have examined the association between household air pollution (HAP) and low birth weight (LBW). Only one study directly measured prenatal carbon monoxide exposures among women enrolled in the RESPIRE randomized stove intervention trial. Aims:The NACER pilot study builds off our earlier experience and aims to: 1) measure personal exposures to carbon monoxide (CO), particulate matter (PM2.5) and polycyclic aromatic hydrocarbons (PAHs) during pregnancy and the first year of infant life; and 2) collect standardized measures of infant weight, length and head circumference, newborn gestational age and infant neurodevelopment. Methods: Guatemalan, indigenous women were recruited through a rural Ministry of Health clinic at &lt; 20 weeks gestation and received prenatal health exams at &lt; 20, 24-28, and 32-36 weeks. Home visits were made 3 times during pregnancy to monitor prenatal HAP. Home visits were made within 48 hours of birth and at 1, 3, 6, 9, and 12 months to assess infant anthropometry and neurodevelopment using a validated 27-item instrument (Rapid Neurodevelopmental Assessment (RNDA)). Personal CO and PM exposures were measured using real time monitors and 5 gas-phase PAHs were measured using passive diffusion badges worn over a 48-hour period. Results: 37 pregnant women were enrolled. Gestational age was confirmed by fetal ultrasound (mean: 15.2 weeks, range 7-20.1). Eleven percent of households used open fires for cooking; 89% used deteriorated vented chimney stoves. Maternal and neonatal exposures to CO, PM2.5 and PAHs will be presented. 29% of infants were low birth weight (&lt; 2,500 grams) and 6% were preterm (&lt; 37 weeks). Among neonates, moderate/severe neurodevelopmental impairment were: fine motor (13%), gross motor (32%), speech (16%), cognition (32%), behavior (13%), vision (45%), hearing (39%), primitive reflexes (23%), and seizures (0). Conclusions: Maternal PM and CO exposures were significantly greater than neonatal exposures. LBW and moderate/severe neurodevelopmental impairment were both high. In a future, larger study we will measure the impact of maternal and neonatal HAP exposures on LBW, preterm delivery and infant neurodevelopmental impairment.

A pilot study characterizing real time exposures to particulate matter and carbon monoxide from cookstove related woodsmoke in rural Peru

Nearly half of the world's population is exposed to household air pollution (HAP) due to long hours spent in close proximity to unvented cooking fires. We aimed to use PM2.5 and CO measurements to characterize exposure to cookstove generated woodsmoke in real time among control (n = 10) and intervention (n = 9) households in San Marcos, Cajamarca Region, Peru. Real time personal particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5), and personal and kitchen carbon monoxide (CO) samples were taken. Control households used a number of stoves including open fire and chimney stoves while intervention households used study-promoted chimney stoves. Measurements were categorized into lunch (9 am–1 pm) and dinner (3 pm–7 pm) periods, where applicable, to adjust for a wide range of sampling periods (2.8–13.1 h). During the 4-h time periods, mean personal PM2.5 exposures were correlated with personal CO exposures during lunch (r = 0.67 p = 0.024 n = 11) and dinner (r = 0.72 p = 0.0011 n = 17) in all study households. Personal PM2.5 exposures and kitchen CO concentrations were also correlated during lunch (r = 0.76 p = 0.018 n = 9) and dinner (r = 0.60 p = 0.018 n = 15). CO may be a useful indicator of PM during 4-h time scales measured in real time, particularly during high woodsmoke exposures, particularly during residential biomass cooking.

Personal Carbon Monoxide Exposures Among Firefighters at Prescribed Forest Burns in the Southeastern United States

ABSTRACT Exposure to combustion products from wildland fires causes respiratory irritation and decreased lung function among firefighters. The authors evaluated carbon monoxide (CO) exposures of a group of wildland firefighters who conducted prescribed burns in the southeastern United States of America. A total of 149 person-days of samples were collected using data logging CO monitors. A questionnaire was administered to collect data on job tasks and self-reported smoke exposure. Overall, the highest exposures were seen amongst firefighters assigned to holding and mop-up tasks (geometric mean [GM]: 2.6 ppm), whereas the lowest were associated with lighting and jobs such as burn boss (GM: 1.6 and 0.3 ppm, respectively). The self-reported smoke exposure showed a significant linear trend with increasing CO exposure. The numbers of acres burned or burn duration, however, were not good predictors of exposure.

Neurodevelopmental performance among school age children in rural Guatemala is associated with prenatal and postnatal exposure to carbon monoxide, a marker for exposure to woodsmoke

We investigated whether early life chronic exposure to woodsmoke, using personal passive 48-h carbon monoxide (CO) as an indicator, is associated with children's neurodevelopmental and behavioral performance. CO measures were collected every 3 months from 2002 to 2005 among mother–child dyads during the Randomized Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) stove intervention trial in San Marcos, Guatemala. From March to June, 2010, study children of age 6–7 years, performed a follow-up non-verbal, culturally adapted neurodevelopmental assessment. We found inverse associations between CO exposure of pregnant mothers during their 3rd trimesters (m=3.8ppm±3.0ppm; range: 0.6–12.5ppm) and child neuropsychological performance. Scores on 4 out of 11 neuropsychological tests were significantly associated with mothers’ 3rd trimester CO exposures, including visuo-spatial integration (p<0.05), short-term memory recall (p<0.05), long-term memory recall (p<0.05), and fine motor performance (p<0.01) measured using the Bender Gestalt-II's Copy, Immediate Recall, and an adapted version of a Delayed Recall Figures drawing, and the Reitan-Indiana's Finger Tapping Tests, respectively. These 4 significant finding persisted with adjustment for child sex, age, visual acuity, and household assets (socio-economic status). Summary performance scores were also significantly associated with maternal 3rd trimester CO when adjusted for these covariates. Other variables accounting for variance but were excluded in our final multiple regression models included the following: HOME environment stimulation score, child examiner, WHO height-for-age percentile, and age that the infant stopped breastfeeding. This seems to be the first study on woodsmoke exposure and neurodevelopment, and the first longitudinal birth cohort study on chronic early life CO exposures, determined by high quality measures of mothers’ and infants’ personal CO exposures, and using well-established, reliable child neuropsychological tests. Further research is needed to replicate our results and inform future interventions and air quality standards for woodsmoke and CO.

ACUTE EFFECTS OF WOODSMOKE EXPOSURE AS MEASURED BY PERSONAL CARBON MONOXIDE ON HEART RATE VARIABILTY IN GUATEMALA

Background and Aims: Evidence suggests that fine particulate air pollution is a cause of cardiovascular disease, but little is known about the effects of indoor air pollution from household solid fuel use in developing countries. In the RESPIRE randomized trial of a chimney woodstove, we examine short-term associations between personal carbon monoxide (CO), as a proxy for woodsdmoke, and heart rate variability (HRV). Methods: Electrocardiogram sessions lasting 20 hours were repeated up to three times among 49 intervention (chimney stove) and 70 control (open fire) women 38 to 84 years of age. HRV values (SDNN, RMSSD, HF, LF, VLF) were recorded for each 30-minute period. Continuous personal CO exposures were measured starting 24 hours before and during each electrocardiogram. Linear mixed effects models with random intercept for subject, random intercept for study day nested within subject, and a first-order autoregressive term within subject-day were used to estimate the association between natural log transformed 30-min HRV and CO (1-hour, 4-hour, and 8-hour moving averages), adjusting for hour of day (dummy variable for each hour), age, body mass index, asset index, ever smoking, secondhand tobacco smoke, wood-fired sauna use, season, ambient temperature, and rainfall. Results: The means of 30-min average personal CO levels were 2.6 (n=4265, SD=2.5, range=0.2-20.6) and 1.0 (n=4426, SD=1.3, range=0.2-9.3) ppm in the open fire and chimney stove groups, respectively. All models we ran suggest HRV increases with personal CO. Each 1 ppm increase in 4-hour moving average CO was associated with a 4.6% (95% CI: 1.2, 8.2) increase in LF and a 2.4% (95% CI: 0.3, 4.6) increase in VLF. Associations with 8-hour moving average CO were similar and were significant for LF, VLF, and RMSSD. Conclusions: Personal exposure to woodsmoke was associated with increased HRV, particularly the low frequency components, suggesting that woodsmoke exposure has acute effects on the autonomic control of the heart.

Indoor and Personal Carbon Monoxide Exposure Risk Assessment in Sample of Apartment Buildings in Santiago, Chile

Indoor carbon monoxide (CO) exposure is considered around the world as one of the most important causes of poisoning with fatal outcomes. This study determined indoor CO levels and personal CO exposure and related risk factors during human activities in 96 apartments in a community of Santiago, Chile during the period from September to December of 2003. Indoor levels and personal exposure were determined using fixed, personal and single-breath CO monitors, respectively. Exposure risk factors and time-activities patterns were evaluated through an ad hoc exposure assessment questionnaire. Regression models were fitted to evaluate the effects of these risks factors on the personal CO levels. The median indoor CO level was 1 ppm; interquartile range (IQR): (0–1). The median personal CO level was 1 ppm; IQR: (0–7); CO exhaled was 3.0 ppm; IQR: (1–33). The number of cigarettes smoked and the levels of indoor environmental CO were significant predictors of the concentration of CO exhaled. This study showed that indoor median levels were below the national standard and the most important predictors of CO exposure were tobacco smoke and the smoking habit in apartments.

Impact of the Improved Patsari Biomass Stove on Urinary Polycyclic Aromatic Hydrocarbon Biomarkers and Carbon Monoxide Exposures in Rural Mexican Women

Background: Cooking with biomass fuels on open fires results in exposure to health-damaging pollutants such as carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs), and particulate matter.Objective: We compared CO exposures and urinary PAH biomarkers pre- and postintervention with an improved biomass stove, the Patsari stove.Methods: In a subsample of 63 women participating in a randomized controlled trial in central Mexico, we measured personal CO exposure for 8 hr during the day using continuous monitors and passive samplers. In addition, first-morning urine samples obtained the next day were analyzed for monohydroxylated PAH metabolites by gas chromatography/isotope dilution/high-resolution mass spectrometry. Exposure data were collected during the use of an open fire (preintervention) and after installation of the improved stove (postintervention) for 47 women, enabling paired comparisons.Results: Median pre- and postintervention values were 4 and 1 ppm for continuous personal CO and 3 and 1 ppm for passive sampler CO, respectively. Postintervention measurements indicated an average reduction of 42% for hydroxylated metabolites of naphthalene, fluorene, phenanthrene, and pyrene on a whole-weight concentration basis (micrograms per liter of urine), and a 34% reduction on a creatinine-adjusted basis (micrograms per gram of creatinine). Pre- and postintervention geometric mean values for 1-hydroxypyrene were 3.2 and 2.0 μg/g creatinine, respectively.Conclusion: Use of the Patsari stove significantly reduced CO and PAH exposures in women. However, levels of many PAH biomarkers remained higher than those reported among smokers.

Measuring the Exposure of Infants and Children to Indoor Air Pollution From Biomass Fuels in the Gambia

O-30C3-2 Background/Aims: Smoke from biomass fuels contains multiple gaseous and particulate pollutants, and is a risk factor for pneumonia, the leading cause of child death worldwide. Few studies have assessed the exposure-response relationship for biomass smoke and pneumonia, primarily because measuring children's exposure is difficult, especially for particulate matter (PM). We report on a study which utilized multiple methods to evaluate children's exposure to PM and carbon monoxide (CO) from biomass fuels. Methods: Seventy-two hours personal CO exposure was measured for 1200 children, with 12%–15% receiving an additional 3–4 CO measurements. In the same subset of children, 72-hours integrated and continuous PM and 72-hours CO were measured in the cookhouse. Personal PM exposure was measured for 20–25 of these children. Usual personal exposure to CO is estimated using a random effects model including child- and household-level covariates. Personal exposure of children to PM is estimated using 3 different approaches, as well as a combined model: (1) combining time-location-activity budget with microenvironment PM; (2) estimating PM exposure using CO exposure combined with stationary CO-PM relationship; and (3) direct measurement of personal PM. Results: Preliminary results show a mean 72-hours CO exposure on children of 1.0 ± 1.3 ppm, with an age distribution of 0.8 ± 0.9 ppm (0–11 months) and 1.1 ± 1.5 ppm (12–59 months). Regression analysis adjusting for child's age, study site, and sex indicates a seasonal pattern for CO exposure, with significantly higher exposure in July, August, and September. Using the CO-PM relationship from a pilot study, estimated average personal PM2.5 exposure for these children would be 189 μg/m3. Conclusion: Children's exposure to PM2.5 in The Gambia is well above WHO Air Quality Guidelines. The results of multiple measurement methods can be combined to estimate children's personal PM2.5 exposure.

Personal child and mother carbon monoxide exposures and kitchen levels: Methods and results from a randomized trial of woodfired chimney cookstoves in Guatemala (RESPIRE)

During the first randomized intervention trial (RESPIRE: Randomized Exposure Study of Pollution Indoors and Respiratory Effects) in air pollution epidemiology, we pioneered application of passive carbon monoxide (CO) diffusion tubes to measure long-term personal exposures to woodsmoke. Here we report on the protocols and validations of the method, trends in personal exposure for mothers and their young children, and the efficacy of the introduced improved chimney stove in reducing personal exposures and kitchen concentrations. Passive diffusion tubes originally developed for industrial hygiene applications were deployed on a quarterly basis to measure 48-hour integrated personal carbon monoxide exposures among 515 children 0-18 months of age and 532 mothers aged 15-55 years and area samples in a subsample of 77 kitchens, in households randomized into control and intervention groups. Instrument comparisons among types of passive diffusion tubes and against a continuous electrochemical CO monitor indicated that tubes responded nonlinearly to CO, and regression calibration was used to reduce this bias. Before stove introduction, the baseline arithmetic (geometric) mean 48-h child (n=270), mother (n=529) and kitchen (n=65) levels were, respectively, 3.4 (2.8), 3.4 (2.8) and 10.2 (8.4) p.p.m. The between-group analysis of the 3355 post-baseline measurements found CO levels to be significantly lower among the intervention group during the trial period: kitchen levels: -90%; mothers: -61%; and children: -52% in geometric means. No significant deterioration in stove effect was observed over the 18 months of surveillance. The reliability of these findings is strengthened by the large sample size made feasible by these unobtrusive and inexpensive tubes, measurement error reduction through instrument calibration, and a randomized, longitudinal study design. These results from the first randomized trial of improved household energy technology in a developing country and demonstrate that a simple chimney stove can substantially reduce chronic exposures to harmful indoor air pollutants among women and infants.

The Impact of a Bus Rapid Transit System on Commutersʼ Exposure to Air Pollutants in Mexico City

MS7-07 Abstract: Bus rapid transit (BRT) systems are being implemented in cities all around the world as a sustainable alternative to conventional public transport, providing a more rapid, metro-like service with separated busways. In addition, the use of modern engine technology leads to reduced vehicular emissions and environmental impact. These factors may further result in a benefit to users of the BRT system due to reduced personal exposures to on-board air pollutants. To our knowledge, this benefit has never before been evaluated experimentally in a Latin American city. The objective of this study was to determine the reduction in commuters’ exposure to air pollutants that may result from a change from a conventional bus transport system to a BRT system in Mexico City. During the summer of 2004, personal exposures to particulate matter (PM2.5 and PM10), benzene, and carbon monoxide (CO) were measured inside 37 conventional buses and 36 minibuses during the morning rush hour along one of the main avenues of Mexico City. During the summer of 2005, after the substitution of the conventional transport modes by a new BRT system with new vehicles, these air pollutants were again measured in 63 BRT buses on the same route. Portable sampling pumps, canisters, and sensors were deployed for these measurements. Significant reductions in personal exposures inside vehicles of the BRT system were found for air pollutants associated with vehicular emissions. Median personal PM2.5 exposures dropped from 152 μg/m3 and 129 μg/m3 inside conventional minibuses and autobuses, respectively, to 99 μg/m3 in the interior of vehicles of the BRT system. Even greater relative reductions were observed for personal benzene exposures, which dropped from 10.2 ppbv and 8.9 ppbv in minibuses and autobuses, respectively, to 4.2 ppbv in BRT vehicles. Similarly, personal CO exposures dropped from 15.8 ppm and 11.4 ppm in minibuses and autobuses to 7.5 ppm in BRT vehicles. However, personal PM10 exposures were not significantly different between conventional transportation modes and BRT vehicles. Finally, commuting times were reduced by approximately 20% in BRT vehicles. These findings show the potential of BRT systems to reduce in-vehicle concentrations of air pollutants in comparison to conventional transport modes. The additional reduction of commuting times further decreases total exposure and thus the health impact of commuting. Therefore, the installation of BRT systems should be encouraged as a means to decrease population exposure to air pollutants, shorten commuting times, and thus elevate the quality of life of public transport users.

Personal carbon monoxide exposure in Helsinki, Finland

Abstract Personal exposure concentrations of carbon monoxide (CO) were measured for the adult urban population of Helsinki, Finland, as part of the multi-centre European EXPOLIS study. The arithmetic mean of the 48 h average personal CO exposure concentration was 1.3 mg m−3 for participants not exposed to environmental tobacco smoke (ETS) and 1.6 mg m−3 for those exposed to ETS at any time and in any microenvironment. The maximum 8 and 1 h exposure values were 2.0 and 2.6 mg m−3, and 4.3 and 5.7 mg m−3, respectively. As tobacco smoke is one of the major sources of CO, therefore the personal mean exposures of ETS participants were higher than the non-ETS participants for all averaging times. The long- and short-term personal exposures were higher in winter than in summer for all participants. In order to analyse in more detail the correlation between the time-activity patterns and exposure levels, cluster analysis was performed using 24 h personal exposure profiles of 1 h moving averages. The results showed clearly that the major source of CO for non-ETS exposed participants are traffic emissions. The majority of the diurnal exposure profiles showed two notable exposure peaks corresponding to the morning and evening traffic rush hours. The time spent in street traffic was the most relevant factor for describing the short-term personal exposures. The more time was spent commuting by car the higher were the exposures. The long-term exposure levels were linked both to the time spent commuting and home location. People living in low-traffic suburban areas and working in downtown spent more time commuting and ended up experiencing similar long-term exposure levels than people who lived in heavy-traffic downtown areas, but spent little time commuting. For ETS exposed participants the personal exposure profiles were dominated by both tobacco smoke and traffic emissions.