Highlights from 4 Papers in 2022

In 2022, Jaffe Group members authored or co-authored 7 papers. Here are highlights from 4:

1. Sedlacek A.J. Lewis E.R., Onasch T.B., Zuidema P., Redemann J., Jaffe D, and Kleinman L.I. “Using the Black Carbon Particle Mixing State to Characterize the Lifecycle of Biomass Burning Aerosols.” Environmental Science & Technology, 56 (20), 14315-14325, http://10.1021/acs.est.2c03851, 2022.

In this analysis, a team, led by Art Sedlacek at Brookhaven National Lab, used data from the Mt. Bachelor Observatory and other sites to show how secondary organic aerosols and black carbon change as wildfire smoke ages. This work has important implications for the climate forcing of smoke.

2. Jaffe, D. A., Schnieder, B., and Inouye, D. “Technical note: Use of PM_2.5 to CO ratio as an indicator of wildfire smoke in urban areas.” Atmos. Chem. Phys., 22, 12695–12704, https://doi.org/10.5194/acp-22-12695-2022, 2022.

In this analysis, Dan and coauthors show how the PM2.5/CO ratio can be used to track wildfire smoke in urban locations.

3. Jaffe, D. A., Ninneman, M., & Chan, H. C. “NOx and O₃ trends at U.S. non-attainment areas for 1995–2020: Influence of COVID-19 reductions and wildland fires on policy-relevant concentrations.” Journal of Geophysical Research: Atmospheres, 127, e2021JD036385. https://doi.org/10.1029/2021JD036385, 2022.

In this analysis, Dan and coauthors examined data from 32 Nonattainment areas in the US (cities that fail to meet the US ozone standard) to better understand the relationship between nitrogen oxides (mainly from vehicles) and Ozone. The analysis showed how ozone was reduced in 2020 in the Eastern U.S. (due to COVID-19 related traffic reductions) but increased in the Western U.S. due to the large number and area of wildfires burning that year.

4. Bernays, N., Jaffe, D. A., Petropavlovskikh, I., and Effertz, P. Comment on “Comparison of ozone measurement methods in biomass burning smoke: an evaluation under field and laboratory conditions” by Long et al. Atmos. Meas. Tech., 15, 3189–3192, https://doi.org/10.5194/amt-15-3189-2022, 2022.

In this analysis, Jaffe-group team member Noah Bernays and coauthors confirmed a significant interference in the measurement of O3 in smoke for some UV instruments. This interference was attributed to the use of manganese chloride as the scrubber material, for example in the Thermo Fisher’s 49i series ozone analyzers. Instruments employing manganese dioxide scrubbers did not show this interference.

Popular Science interviews Dan Jaffe on wildfire pollution

Popular Science recently took a look at how wildfires are polluting our air. They cited research about the increase in two pollutants due to wildfires: PM_2.5 (fine particulate matter less than 2.5 micrometers in size) and ozone. This research, conducted by Dmitri Kalashnikov, a doctoral student in environmental science at Washington State University Vancouver, found the co-occurrence of these two pollutants has increased significantly in the last 20 years in the western U.S. during July–September, as wildfires have increased.

Dan Jaffe noted that understanding the relationship between PM_2.5 and ozone levels isn’t straightforward. He and Jaffe Group researchers have previously found that the most extreme levels of PM_2.5 and ozone tend not to occur on the same days. He says that the new paper is still “definitely a step forward.”

Understanding and responding to the increase in wildfires and their unhealthy pollution are important issues for western communities and policy makers.

Read the Popular Science article

Matt Ninneman and Dan Jaffe publish 2 new papers on ozone

“The impact of wildfire smoke on ozone production in an urban area: Insights from field observations and photochemical box modeling”

map of California showing Bakersfield site and fire locations — Map of California showing the locations of the Bakersfield Municipal Airport (BMA) site and the Ferguson, Natchez, Carr, Mendocino Complex, Donnell, and Hirz fires.

In this recently published paper, postdoctoral research associate Matt Ninneman and Dan Jaffe examined the effect of wildfire smoke on ozone (O₃) production at an urban site in Bakersfield, CA. They used data from smoky and non-smoky weekdays in summer 2018. During this period, there were several active wildfires in northern California. The authors utilized a photochemical box model to analyze the data. The box model simulations indicate that maximum O₃ production rates were about two times faster on smoky weekdays compared to non-smoky weekdays. Model sensitivity tests for smoky weekdays showed that (1) O₃ was sensitive to both oxides of nitrogen (NO_x) and volatile organic compounds (VOCs) and (2) aldehydes significantly affected O₃ formation. Their results suggest that “a combination of anthropogenic VOC and NO_x reductions will be the most effective strategy for decreasing O₃ on typical non-smoky days.” However, only reductions in NO_x are expected to have a significant impact on lowering O₃concentrations on typical smoky days, since VOC levels in smoke plumes are high.

Read the full paper in Atmospheric Environment

“Observed relationship between ozone and temperature for urban nonattainment areas in the United States”

In a second recently published paper, Matt Ninneman and Dan Jaffe investigated the observed relationship between ground-level ozone (O₃) and temperature from 1995 to 2020 at 20 U.S. cities that violate regulatory requirements for ground-level O₃. They found that the median slope of the ground-level O₃versus temperature relationship declined in all regions, and the correlation between ground-level O₃and temperature weakened over time in the eastern and midwestern U.S. In the western U.S., ground-level O₃ has declined more slowly and the correlation between ground-level O₃ and temperature has changed negligibly due to the combined influence of high background O₃and wildfire smoke. This suggests that meeting regulatory requirements for ground-level O₃in the western U.S. will be more challenging than in other parts of the country.

Read the full paper in Atmosphere

Air purifiers can help protect from COVID-19 and smoke

The Washington Post interviewed Dan Jaffe for a recent article about the benefits of air purifiers against airborne particles such as those from coronavirus and also wildfires. The article offers advice on what to look for in an air purifier and how to use one. Their advice in a nutshell: use HEPA filters, fit the purifier to the space, set it up correctly, and use the purifier in the rooms where people are. And one more thing—there is an option that is cheaper than spending $200–1000 for a purifier! At the end of the article, they cite the Jaffe Group’s research into using a standard box fan with an attached MERV-13 furnace filter to clean particulate matter from the air. Making a simple air purifier is an easy project you can do at home. The article also mentions that wearing masks is important.

Read the Washington Post article

Learn how to make an air purifier for your home

Smoky summer ahead?

Last summer was a smoke-filled one in Washington State. Will this summer be similar? Well, the drought conditions in Washington State have led to forests and grasslands filled with wildfire fuel. If you live in the Pacific Northwest, now is the time to prepare for the possibility of a smoky summer. Dan Jaffe was interviewed by KUOW recently and advised residents to get prepared. “You don’t have to spend a lot of money to actually do a pretty good job of protecting your indoor air quality.” You can make a simple smoke filter for your home with a box fan and a furnace filter.

Listen and read the KUOW report

Learn how to make an air purifier for your home

Low-cost filtration method improves air quality during smoke events—see the new paper

A new paper by group members Dr. Nate May, Clara Dixon, and Dr. Dan Jaffe evaluates the effectiveness of low-cost air filter units during wildfire smoke events. The increased wildland fire activity in the western US in recent years produces high concentrations of fine particulate matter (PM_2.5), which negatively affects the health of millions of people. During wildfire smoke events, staying indoors is often recommended. However, how good is indoor air quality during smoke events? The authors looked at PM_2.5measurements from the PurpleAir sensor network, a publicly available network of low-cost air quality sensors located indoors and outdoors. They also analyzed the effectiveness of residential filter units in reducing indoor PM_2.5. One low-cost DIY filtration method consists of attaching a Minimum Efficiency Rating Value-13 (MERV-13) fan filter to a standard box fan. This method was found to be highly effective at reducing indoor PM_2.5when recirculating air in a single room.

Read the full paper in Aerosol and Air Quality Research

See the video on how to make your own air purifier at home

A new age of wildfires

wildire in Pacific Northwest — Credit: Mark Stone/University of Washington.

A new article on the University of Washington website looks at the growing severity of wildfires and the broad research that the university is doing on their impacts. The article highlights the work that we do on wildfires’ effects on air quality. Also featured is the Joel Thornton lab at UW Seattle and the work of other UW researchers who study wildfires and forests.

Faculty and students install instruments at Mt. Bachelor Observatory. — Claire Buysse and Dan Jaffe set up radiometers to measure UV light on the top of Mt. Bachelor Observatory, August 2019. Credit: Mark Stone/University of Washington.

In the summer of 2019, UW photographer Mark Stone visited Mt. Bachelor Observatory, as well as other research sites, and captured the UW’s research in stunning photographs.

Read the article.

The “smoke apocalypse” and indoor air quality: Media reports with Dan Jaffe

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.

See links to all of the articles and videos along with descriptions

Videos highlight research

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.

VIDEO: Jaffe team research trip to Boise, ID, Aug. 2019

VIDEO: Jaffe team working at Mt. Bachelor Observatory, Bend, OR, Sept. 2019

New critical review of wildland fire impacts on air quality

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.

U.S. wildire area burned and federal suppression costs for 1985-2018 — Total U.S. wildfire area burned (ha) and federal suppression costs for 1985–2018 scaled to constant (2016) U.S. dollars. Trends for both wildfire area burned and suppression indicate about a four-fold increase over a 30-year period. Data source: National Interagency Fire Center, Fire Information Statistics, accessed December 2, 2019. https://www.nifc.gov/fireInfo/fireInfo_statistics.html.

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.

Read the paper here

Free paper eprints available here