In September, Seattle and the Puget Sound region recorded the worst air quality ever. For example, in the Georgetown neighborhood of Seattle it was 314 on the air quality index on September 17. During our area’s recent smoke apocalypse, Dr. Dan Jaffe has been a frequent media guest. He has been interviewed by the Seattle Times, Crosscut, KIRO7, KOMONews, KOMOAM, KING5, and Q13Fox. Dan discussed his work on indoor air quality during the wildfire season and showed how to make a very effective DIY air purifier using a box fan and a MERV 13 furnace filter.
Check out our new Videos page! There you’ll find videos that showcase the group’s research over the years. The page includes videos on airborne research in 2001 to current air quality research at Mt. Bachelor Observatory in Bend, Oregon.
Undergraduate researcher Shahbaz Qureshi recorded two videos about the group’s research in the summer of 2019. One shows the Jaffe team working at Mt. Bachelor Observatory, where they are setting up and maintaining research equipment. The second video focuses on a research trip to Boise, Idaho. During the summer of 2019, we measured volatile organic carbons, NOx, and other compounds at a site near Boise in order to understand the impact of forest fire emissions on the tropospheric photochemistry of ozone and aerosols at downwind sites. Qureshi has been conducting research with the Jaffe Group for the last year and graduated from the University of Washington Bothell in June 2020.
Dr. Dan Jaffe is the lead author on a critical review that examines the processes that influence wildfires and prescribed fires and their effects on air quality in the U.S. This review, “Wildfire and prescribed burning impacts on air quality in the United States,” is published in the June issue of the Journal of the Air & Waste Management Association. This paper is the result of a collaboration between Dan Jaffe and Susan O’Neill, Narasimhan Larkin, Amara Holder, David Peterson, Jessica Halofsky, and Ana Rappold. These coauthors have brought their range of expertise to the issues related to wildland fires and have examined each of the processes influencing these fires and also the effects of the fires, “including the natural role of wildland fire, forest management, ignitions, emissions, transport, chemistry, and human health impacts.”
Large wildfires in the U.S. are becoming more common, and their emissions of particulate matter (PM) and gaseous compounds negatively impact air quality and human health. The air quality trend in the U.S. has been improving in the last decades. However, seasonal wildfires threaten to undermine this progress in parts of the country. The area burned by wildland fires has grown significantly in the last few decades due to “past forest management practices, climate change, and other human factors.” This has resulted in millions of people experiencing high levels of air pollution. As cities and towns have spread further into wildlands, costs for fire suppression (to protect human developments) and the consequences of fires have increased significantly.
In this review, Dr. Jaffe and his coauthors describe the current state of the research and identify key data gaps. Their goal is to identify areas that are well understood and areas that need more research. They recommend eight specific areas for future research.
Research by Jaffe Group postdoctoral scholars Dr. James Laing and Dr. Boggarapu Praphulla Chandra has resulted in two new peer-reviewed publications. Both papers examine methods used for measuring air pollutants from wildfires.
The first paper, “Comparison of filter-based absorption measurements of biomass burning aerosol and background aerosol at the Mt. Bachelor Observatory,” was recently published in Aerosol and Air Quality Research. The authors, Dr. James Laing, Dr. Daniel Jaffe, and Dr. Arthur Sedlacek, III, evaluated the upgraded aethalometer (AE33, Magee Scientific) and the new tricolor absorption photometer (TAP, Brechtel) to assess their effectiveness in measuring wildfire aerosol plumes. These instruments measure light-absorbing organic aerosols, which are emitted primarily in biomass burning. Both instruments were deployed at Mt. Bachelor Observatory (MBO) in central Oregon during the summer of 2016. Each instrument uses a similar methodology (“light extinction through an aerosol-laden filter”), but each has a unique set of corrections necessary to address filter-based bias and other issues. The coauthors found that when using the AE33 manufacturer’s recommended settings, correction factors that are larger than the manufacturer’s recommended factor are needed to calculate accurate absorption coefficients and equivalent black carbon.
In the second paper, coauthors Dr. Boggarapu Praphulla Chandra, Dr. Crystal McClure, JoAnne Mulligan, and Dr. Daniel Jaffe evaluated the use of dual-bed thermal desorption (TD) tubes with an auto-sampler to sample volatile organic compounds (VOCs). Their paper, “Optimization of a method for the detection of biomass-burning relevant VOCs in urban areas using thermal desorption gas chromatography mass spectrometry,” appeared in the journal Atmosphere in March. For this study, the authors utilized a portable, custom-made “suitcase” sampler, which they deployed in Boise, ID, during the summer of 2019.
The sampler continuously collected samples of VOCs on the TD tubes for up to six days without the need for continuous on-site monitoring. The tubes were later transferred to the lab for analysis using thermal desorption gas chromatography mass spectrometry (TD-GC-MS) to detect VOCs.
They found that “reactive and short-lived VOCs such as acetonitrile (a specific chemical tracer for biomass burning), acetone, n-pentane, isopentane, benzene, toluene, furan, acrolein, 2-butanone, 2,3-butanedione, methacrolein, 2,5- dimethylfuran, and furfural . . . can be quantified reproducibly with a total uncertainty of ≤30% between the collection and analysis, and with storage times of up to 15 days.”
Their research demonstrates the applicability of this flexible method for ambient VOC speciation and determining the influence of forest fire smoke. This sampling method offers a practical alternative for urban air quality monitoring sites because its portability does not require the installation of a complex and expensive instrument and its auto-sampling technique does not require continuous on-site monitoring.
A newly published paper by Claire Buysse and coauthors Aaron Kaulfus, Udaysankar Nair, and Dan Jaffe explores the the impact of wildfire smoke on urban air quality. The paper, published in Environmental Science & Technology, describes the authors’ study of ozone (O3) impacts from smoke on 18 western US cities during July–September 2013–2017. They used monitoring data from ground-based sites and identified smoke using the satellite-based hazard mapping system (HMS) fire and smoke product provided by the National Oceanic and Atmospheric Administration.
Their findings include the following:
- O3 and particulate matter <2.5 μm in diameter (PM2.5) are elevated at most sites on days influenced by smoke, while nitrogen oxides (NOx) are not consistently elevated at all sites.
- PM2.5 and O3 exhibit a nonlinear relationship: O3 increases with PM2.5 at low to moderate PM2.5 and then O3 decreases at higher PM2.5.
- On days influenced by smoke, the rate of increase of morning O3 is higher and the NO/NO2 ratios are lower.
- The HMS product is useful for identifying smoke. However, because O3 and PM2.5 are elevated on days before and after HMS-identified smoke events, some smoke events are not being detected.