Megan Bergauff

Urinary Levoglucosan as a Biomarker of Wood Smoke Exposure: Observations in a Mouse Model and in Children

Background Biomass smoke is an important source of particulate matter (PM), and much remains to be discovered with respect to the human health effects associated with this specific PM source. Exposure to biomass smoke can occur in one of two main categories: short-term exposures consist of periodic, seasonal exposures typified by communities near forest fires or intentional agricultural burning, and long-term exposures are chronic and typified by the use of biomass materials for cooking or heating. Levoglucosan (LG), a sugar anhydride released by combustion of cellulose-containing materials, is an attractive candidate as a biomarker of wood smoke exposure. Objectives In the present study, Balb/c mice and children were assessed for LG in urine to determine its feasibility as a biomarker. Methods We performed urinary detection of LG by gas chromatography/mass spectrometry after intranasal instillations of LG or concentrated PM (mice) or biomass exposure (mice or humans). Results After instillation, we recovered most of the LG within the first 4 hr. Experiments using glucose instillation proved the specificity of our system, and instillation of concentrated PM from wood smoke, ambient air, and diesel exhaust supported a connection between wood smoke and LG. In addition, LG was detected in the urine of mice exposed to wood smoke. Finally, a pilot human study proved our ability to detect LG in urine of children. Conclusions These results demonstrate that LG in the lungs is detectable in the urine of both mice and humans and that it is a good candidate as a biomarker of exposure to biomass smoke.

Residential indoor PM2.5 in wood stove homes: follow-up of the Libby changeout program

UNLABELLED In 2005 through 2008, a small rural mountain valley community engaged in a woodstove changeout program to address concerns of poor ambient air quality. During this program, we assessed changes to indoor air quality before and after the introduction of a new, lower emission woodstove. We previously reported a >70% reduction in indoor PM(2.5) concentrations in homes following the installation of a new Environmental Protection Agencys-certified stove within the home. We report here on follow-up of the experiences in these and other homes over three winters of sample collection. In 21 homes, we compared pre-changeout PM(2.5) concentrations [mean (s.d.) = 45.0 (33.0) μg/m(3)] to multiple post-changeout measures of PM(2.5) concentrations using a DustTrak. The mean reduction (and 95% confidence interval) from pre-changeout to post-changeout was -18.5 μg/m(3) (-31.9, -5.2), adjusting for ambient PM(2.5) , ambient temperature, and other factors. Findings across homes and across years were highly variable, and a subset of homes did not experience a reduction in PM(2.5) following changeout. Reductions were also observed for organic carbon, elemental carbon, and levoglucosan, but increases were observed for dehydroabietic acid and abietic acid. Despite overall improvements in indoor air quality, the varied response across homes may be due to factors other than the introduction of a new woodstove. PRACTICAL IMPLICATIONS Biomass combustion is a common source of ambient PM(2.5) in many cold-climate communities. The replacement of older model woodstoves with newer technology woodstoves is a potential intervention strategy to improve air quality in these communities. In addition to ambient air, woodstove changeouts should improve residential indoor air quality. We present results from a multi-winter study to evaluate the efficacy of woodstove changeouts on improving indoor air quality. Reductions in indoor PM(2.5) were evident, but this observation was not consistent across all homes. These findings suggest that other factors beyond the introduction of an improved wood burning device are relevant to improving indoor air quality in wood burning homes.

Determination and evaluation of selected organic chemical tracers for wood smoke in airborne particulate matter

PM2.5 is released during combustion reactions and industrial processes. The chemical composition of PM can be a strong indicator of its origin, or source. A method was developed for the determination of selected chemical tracers for wood smoke in particulate matter using solvent extraction and GCMS analysis. The chosen tracers were levoglucosan, dehydroabietic acid, abietic acid, vanillin, acetovanillone, guaiacol, and 4-ethylguaiacol. Deuterated compounds of similar structure to the chosen tracers were employed as standards in the procedure to eliminate the possible effects of incomplete extraction from the filters and other fluctuations throughout the analysis period. The method had recoveries of 105 ± 7.7% for levoglucosan, 64 ± 3.5% for dehydroabietic acid, 60±3.6% for abietic acid, 98±2.2% for vanillin, 102 ± 3.8% for acetovanillone, 104 ± 4.9% for guaiacol and 116 ± 4.7% for 4-ethylguaiacol. The developed analytical method was applied to ambient particulate matter samples collected in Libby, MT. Libby has been designated as a non-attainment area for current USEPA PM2.5 standards, and a recent study showed that 82% of the PM2.5 in Libby resulted from residential wood smoke. The concentrations of levoglucosan, dehydroabietic acid, and abietic acid were found to be strongly correlated with total PM2.5 levels in Libby, while the methoxyphenols did not show a correlation to PM2.5 levels. Levoglucosan, dehydroabietic acid, and abietic acid were found to be suitable tracers for wood smoke in particulate matter.

Urinary levoglucosan as a biomarker of wood smoke: results of human exposure studies.

Urinary levoglucosan was investigated as a potential biomarker of wood smoke exposure in two different controlled experimental settings. Nine subjects were exposed to smoke from a campfire in a controlled setting, and four were exposed to smoke from an older-model wood stove. All subjects were asked to provide urine samples before and after exposure, and to wear personal particulate matter with a diameter of ≤2.5 μm (PM2.5) monitors during exposure. Urinary levoglucosan measurements from both studies showed no consistent response to the smoke exposure. A third experiment was conducted to assess the contribution of dietary factors to urinary levoglucosan levels. Nine subjects were asked to consume caramel and provide urine samples before and after consumption. Urinary levoglucosan levels increased within 2 h of caramel consumption and returned to pre-exposure levels within 24 h. These studies suggest that diet is a major factor in determining urinary levoglucosan levels and that recent dietary history needs to be taken into account for future work involving levoglucosan as a biomarker of wood smoke exposure.

The impact of a community-wide woodstove changeout intervention on air quality within two schools

Due to temperature inversions and widespread residential woodstove use, Libby, Montana historically experienced elevated levels of ambient woodsmoke PM2.5 throughout the winter months. In an effort to reduce wintertime PM2.5, a large community–wide woodstove changeout was conducted between 2005 and 2007, removing nearly 1 200 old polluting stoves from service. To determine the impact of this intervention on indoor air quality, PM2.5 sampling was conducted in the gymnasiums of an elementary and middle school before, during, and after the woodstove changeout over a four–year period. Throughout the program, results showed that indoor PM2.5 concentrations at the elementary school were moderately high regardless of year or season (mean±sd, 31.9±14.1 µg/m 3 ), ranging from 11.0 µg/m 3 to 79.3 µg/m 3 . At the middle school, the mean was 12.2±11.2 µg/m 3 , with no differences by season. Although there was an overall improvement in ambient air quality (and reduction of woodsmoke–PM2.5) when comparing pre– and post– changeout PM2.5 concentrations, results suggest that the community–wide woodstove changeout did not have a significant impact on indoor air quality within the gymnasiums over this same time period. These findings are supported by the results of selected chemical markers of woodsmoke measured from indoor PM (including levoglucosan) at both schools, which also demonstrated no significant reductions throughout the four–year sampling program.

Residential indoor PM 2.5 in wood stove homes

UNLABELLED In 2005 through 2008, a small rural mountain valley community engaged in a woodstove changeout program to address concerns of poor ambient air quality. During this program, we assessed changes to indoor air quality before and after the introduction of a new, lower emission woodstove. We previously reported a >70% reduction in indoor PM(2.5) concentrations in homes following the installation of a new Environmental Protection Agencys-certified stove within the home. We report here on follow-up of the experiences in these and other homes over three winters of sample collection. In 21 homes, we compared pre-changeout PM(2.5) concentrations [mean (s.d.) = 45.0 (33.0) μg/m(3)] to multiple post-changeout measures of PM(2.5) concentrations using a DustTrak. The mean reduction (and 95% confidence interval) from pre-changeout to post-changeout was -18.5 μg/m(3) (-31.9, -5.2), adjusting for ambient PM(2.5) , ambient temperature, and other factors. Findings across homes and across years were highly variable, and a subset of homes did not experience a reduction in PM(2.5) following changeout. Reductions were also observed for organic carbon, elemental carbon, and levoglucosan, but increases were observed for dehydroabietic acid and abietic acid. Despite overall improvements in indoor air quality, the varied response across homes may be due to factors other than the introduction of a new woodstove. PRACTICAL IMPLICATIONS Biomass combustion is a common source of ambient PM(2.5) in many cold-climate communities. The replacement of older model woodstoves with newer technology woodstoves is a potential intervention strategy to improve air quality in these communities. In addition to ambient air, woodstove changeouts should improve residential indoor air quality. We present results from a multi-winter study to evaluate the efficacy of woodstove changeouts on improving indoor air quality. Reductions in indoor PM(2.5) were evident, but this observation was not consistent across all homes. These findings suggest that other factors beyond the introduction of an improved wood burning device are relevant to improving indoor air quality in wood burning homes.

Residential indoor PM2.5in wood stove homes: follow-up of the Libby changeout program: Residential indoor PM2.5in wood stove homes

UNLABELLED In 2005 through 2008, a small rural mountain valley community engaged in a woodstove changeout program to address concerns of poor ambient air quality. During this program, we assessed changes to indoor air quality before and after the introduction of a new, lower emission woodstove. We previously reported a >70% reduction in indoor PM(2.5) concentrations in homes following the installation of a new Environmental Protection Agencys-certified stove within the home. We report here on follow-up of the experiences in these and other homes over three winters of sample collection. In 21 homes, we compared pre-changeout PM(2.5) concentrations [mean (s.d.) = 45.0 (33.0) μg/m(3)] to multiple post-changeout measures of PM(2.5) concentrations using a DustTrak. The mean reduction (and 95% confidence interval) from pre-changeout to post-changeout was -18.5 μg/m(3) (-31.9, -5.2), adjusting for ambient PM(2.5) , ambient temperature, and other factors. Findings across homes and across years were highly variable, and a subset of homes did not experience a reduction in PM(2.5) following changeout. Reductions were also observed for organic carbon, elemental carbon, and levoglucosan, but increases were observed for dehydroabietic acid and abietic acid. Despite overall improvements in indoor air quality, the varied response across homes may be due to factors other than the introduction of a new woodstove. PRACTICAL IMPLICATIONS Biomass combustion is a common source of ambient PM(2.5) in many cold-climate communities. The replacement of older model woodstoves with newer technology woodstoves is a potential intervention strategy to improve air quality in these communities. In addition to ambient air, woodstove changeouts should improve residential indoor air quality. We present results from a multi-winter study to evaluate the efficacy of woodstove changeouts on improving indoor air quality. Reductions in indoor PM(2.5) were evident, but this observation was not consistent across all homes. These findings suggest that other factors beyond the introduction of an improved wood burning device are relevant to improving indoor air quality in wood burning homes.