Do Storage Conditions Affect Collected Cookstove Emission Samples? Implications for Field Studies
Citation:
Mutlu, E., T. Cristy, S. Waidyanatha, R. Chartier, J. Jetter, Todd Krantz, G. Shen, W. Champion, B. Miller, J. Richey, B. Burbank, AND C. Rider. Do Storage Conditions Affect Collected Cookstove Emission Samples? Implications for Field Studies. ANALYTICAL LETTERS. Taylor & Francis, Inc., Philadelphia, PA, , NA, (2022).
Impact/Purpose:
Household air pollution from solid-fuel stoves is the most significant environmental problem that affects human health worldwide. The WHO (World Health Organization) estimates that 3-4 million premature deaths annually are caused by household air pollution, mainly from emissions from cookstoves in the developing world. Additionally, household solid fuel use contributes significantly to ambient black carbon, and transboundary transport of pollutants from millions of stoves in Asia affects ambient air quality in the western U.S. The EPA ORD (Office of Research and Development) is conducting research and activities to address the problem in coordination with a much larger international effort led by the Clean Cooking Alliance. This article provides an evaluation of storage stability and composition of cookstove emission filter samples.
Description:
Cookstove emissions are a significant source of indoor air pollution and have been associated with various acute and chronic illnesses in children and adults. Polycyclic aromatic compounds (PACs), ubiquitous environmental contaminants, are associated with exposure to woodsmoke emissions and subsequent health effects. The levels of extractable organic material (EOM), particulate matter (PM), and PACs in emissions are some endpoints that researchers use to evaluate emissions from combustion of fuels. An important question is whether the samples collected in the field or in laboratory settings are stable over the duration of the research. To investigate this, filters were collected to mimic field conditions and laboratory conditions. Red oak was burned in a natural-draft stove and particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5) was collected on polytetrafluoroethylene (PTFE) filters. Filters were stored at either ambient temperature (~25°C), -20°C, or -80 °C up to 3 months and extracted in dichloromethane. The effects of storage temperature and length on stability were evaluated by quantifying EOM, PM2.5, and PAC levels in the filter extracts. PM2.5 in both simulated field and laboratory samples was similar regardless of the storage condition or duration. The percent EOM was estimated by gravimetric methods. Laboratory filters had lower EOM than simulated field filters. A two-way ANOVA model with fixed effects for storage time and temperature showed an interaction effect between the time and temperature variables; the effect of storage temperature differed between times only for the field samples while no statistical difference was found for the laboratory samples. The extracts were also analyzed by gas chromatography and 22 PACs were quantified to determine similarities and/or differences between the conditions. A general trend was observed where lower mass PACs decreased more rapidly (likely due to higher volatility) compared to the higher mass compounds, which either increased or slightly decreased. Taken collectively, these data suggest that storing samples in colder conditions may help maintain the stability of compounds such as PACs.
