Do Storage Conditions Affect Collected Cookstove Emission Samples? Implications for Field Studies

Abstract

Cookstove emissions are a significant source of indoor air pollution in developing countries and rural communities world-wide. Considering that many research sites for evaluating cookstove emissions and interventions are remote and require potentially lengthy periods of particulate matter (PM) filter sample storage in sub-optimal conditions (e.g., lack of cold storage), an important question is whether samples collected in the field are stable over time. To investigate this, red oak was burned in a natural-draft stove, and fine PM (PM_2.5) was collected on polytetrafluoroethylene filters. Filters were stored at either ambient temperature or more optimal conditions (−20 °C or −80 °C) for up to 3 months and extracted. The effects of storage temperature and length on stability were evaluated for measurements of extractable organic matter (EOM), PM_2.5, and polycyclic aromatic compound (PAC) levels in the filter extracts. A parallel, controlled laboratory condition was also evaluated to further explore sources of variability. In general, PM_2.5 and EOM in both simulated field and laboratory samples were similar regardless of the storage condition or duration. The extracts were also analyzed by gas chromatography to quantify 22 PACs and determine similarities and/or differences between the conditions. PAC levels were a more sensitive stability measure in differentiating between storage conditions. The findings suggest that measurements are relatively consistent across storage duration/temperatures for filter samples with relatively low EOM levels. This study aims to inform protocols and filter storage procedures for exposure and intervention research conducted in low- and middle-income countries where studies may be budget- and infrastructure-limited.

Keywords:

• Cookstoves
• extractable organic matter (EOM)
• fine particulate matter (PM2.5)
• polycyclic aromatic compounds (PACs)
• polycyclic aromatic hydrocarbons (PAHs)

Acknowledgments

Authors would like to thank Mr Bradley J. Collins, Dr Jacky Rosati, and Dr Hannah Liberatore for their review of this manuscript. This work was supported by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences (NIEHS), Intramural Research project ZIA ES103316-04. Additional support was received from the NIEHS Global Environmental Health Program. This work was conducted for the National Toxicology Program by Battelle under the contract number HHSN273201000016C. This document has been reviewed in accordance with U.S. Environmental Protection Agency (EPA) policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. The views expressed in this article are those of the authors and do not necessarily reflect the views or policies of the U.S. EPA. The authors declare no competing financial interest.