Skip to content
Jaffe Group

Category: Publications

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 PM2.5 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.

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 (NOx) and volatile organic compounds (VOCs) and (2) aldehydes significantly affected O3 formation. Their results suggest that “a combination of anthropogenic VOC and NOx reductions will be the most effective strategy for decreasing O3 on typical non-smoky days.” However, only reductions in NOx are expected to have a significant impact on lowering O3 concentrations 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 O3 versus temperature relationship declined in all regions, and the correlation between ground-level O3 and 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 O3 and wildfire smoke. This suggests that meeting regulatory requirements for ground-level O3 in the western U.S. will be more challenging than in other parts of the country.

Read the full paper in Atmosphere

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 (PM2.5), 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 PM2.5 measurements 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 PM2.5. 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 PM2.5 when 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

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

2 new papers explore methods for measuring biomass burning pollutants

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.

Read the full paper.

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.

Suitcase thermal desorption VOC auto-sampler 4-2020
(a) Internal view of the volatile organic compound (VOC) suitcase sampler; (b) Flow diagram of the VOC suitcase sampler; (c) Schematic diagram of the dual-bed TD tubes.

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.

Read the full paper.

Wildfires are causing extreme PM in the western US

Wildfire smoke on 9/6/2017
Wildfire smoke covering the Pacific Northwest and British Columbia on September 6, 2017, from MODIS true color reflectance image. Red dots represent fire locations. Source: https://worldview.earthdata.nasa.gov.

New research by James Laing and Dan Jaffe shows how increases in wildfire smoke have impacted air quality in the western US. Their recent paper, published in the June 2019 issue of EM—The Magazine for Environmental Managers, describes the changing air quality picture for western states. Even though air quality in most of the US has improved in the last four decades, due in large part to the US Clean Air Act regulations, it is not improving in much of the western US. The reason for the decrease in air quality in western states is wildfire smoke.

In 2017 and 2018, wildfires caused the largest daily mean concentrations of fine particulate matter (PM2.5; particles with diameter less than 2.5 μm) ever measured at monitoring sites in the US. Some of the extreme PM2.5 events of 2017–2018 include the following:

  • Seeley Lake, Montana, September 6, 2017—Highest daily PM2.5 on record (642 μg/m3). In August-September 2017, there were 35 days with PM2.5 > 150 μg/m3 and 18 with PM2.5 > 250 μg/m3.
  • Ventura, California, December 6, 2017—PM2.5 of 557 μg/m3, with a two-week average concentration of 165 μg/m3.
  • Seattle, Washington, August 21, 2018—Highest daily PM2.5 ever recorded in Seattle (110 μg/m3).
  • Medford, Oregon, September 6, 2017—Highest daily PM2.5 ever recorded in Medford (268 μg/m3), and eight days over 100 μg/m3 in 2017.

To put these measurements in context, the US Environmental Protection Agency (EPA) has set the daily PM2.5 standard at 35 μg/m3 (98th percentile < 35 μg/m3, averaged over 3 years). The EPA has also defined PM2.5 > 150 μg/m3 as very unhealthy and PM2.5 > 250 μg/m3 as hazardous. PM2.5 is such a health hazard because it can travel deep into the respiratory system due to its small size. Despite the gains in air quality in the US, about 30 million people live where the PM2.5 standard is not being met.

The estimated increase in the number and size of wildfires in the future raises issues for public officials and environmental managers. Complying with air quality standards and reducing human exposure to PM2.5 are causes for concern in the western US now and going forward.

Read the full paper here

Background ozone and implications for air quality management

In a new paper published in Elementa, Dan Jaffe and his coauthors look at background ozone in the US and how it influences whether states can meet air quality standards. Background ozone (O3) includes “contributions from natural and foreign sources of O3 that cannot be controlled by precursor emissions reductions solely within the US.” Understanding background O3 is necessary for air quality management overall and for states and municipalities to meet national air quality standards.

They examined over 100 published studies in order to assess what is the current knowledge about the distribution, trends, and sources of background ozone in the continental US. They found that “noncontrollable O3 sources, such as stratospheric intrusions or precursors from wildfires, can make significant contributions to O3 on some days, but it is challenging to quantify accurately these contributions.” In order to address this shortcoming, they recommend a more coordinated and focused approach to understanding background ozone in the US: improvements in the monitoring network, large-scale field experiments, more accurate and consistent chemical transport models, and more detailed observations of wildfires.

Read the paper here

US particulate matter air quality improves except in wildfire-prone areas—See our new group paper!

A new paper authored by Crystal McClure and Dan Jaffe describes the increasing  particulate matter (PM2.5) pollution over the last few decades in the Northwest. This research, published Monday in Proceedings of the National Academy of Sciences, analyzed PM2.5 data from rural monitoring (IMPROVE) sites across the contiguous US for 1988–2016. They found a decreasing trend  in PM2.5, and cleaner air, around the country except for in the Northwest, where there is a positive trend in PM2.5. This positive trend is associated with total carbon, a marker for wildfires.

The figure below shows trends in PM2.5 for 1988–2016 for the 98th quantile, that is, the seven highest days. In most of the Northwest (red and orange areas), these days are getting worse, while most of the country has improving air quality trends (purple, blue, and green areas).

Figure 1 in PNAS paper US particulate matter air quality improves except in wildfire-prone areas
The 98th Quantile Regression of PM2.5 trends. Observed PM trends for 1988–2016 (calculated using QR methods) from IMPROVE sites are shown by black dots with corresponding values in µg·m−3·y−1. Krige-interpolated values (calculated from observed data) are shown by the color ramp. Solid black lines with arrows (indicating direction) show the boundary where the Krige-interpolated PM2.5 trends within have a 90% probability of being positive or negative. Of the 157 sites, 92 show statistical significance (8 positive/84 negative).

Read the abstract on the PNAS website

This new research has been garnering a lot of press since its publication:

2018 begins with 3 new group papers

The Jaffe Group has kicked off 2018 with 3 new publications.

  • Xi Gong, et al., Ozone in China: Spatial distribution and leading meteorological factors controlling O3 in 16 Chinese cities. Gong and her coauthors examined ozone (O3) concentrations in 16 Chinese cities and developed a statistical model to estimate the maximum daily 8-hour (MDA8) O3 during 2014–2016. They found that the Generalized Additive Model (GAM) captured 43-90% of daily O3 variations. They also identified the leading meteorological factors that affect O3 for each city. Read the full paper here.
Average 8-hour MDA8 (ug/m3) ozone concentrations for 16 Chinese cities, 2014-2016
Average maximum daily 8-hour (MDA8, ug/m3) ozone concentrations for 16 Chinese cities, 2014-2016.
  • Pao Baylon, et al., Impact of biomass burning plumes on photolysis rates and ozone formation at the Mount Bachelor Observatory. Baylon and his coauthors examined biomass burning (BB) events at Mt. Bachelor Observatory (MBO) during the summer of 2015. Biomass burning can emit large amounts of aerosols and gases into the atmosphere. These plumes contain compounds that react with sunlight to produce ozone, a health hazard to sensitive individuals. The photochemistry in BB plumes is poorly understand. Baylon and his coauthors addressed this knowledge gap by using MBO data to calculate ozone production rates and comparing these values with modeled values. Read the full paper here.
  • Lei Zhang, et al., A quantification method for peroxyacetyl nitrate (PAN) using gas chromatography (GC) with a non-radioactive pulsed discharge detector (PDD). Zhang and his coauthors developed a method for continuous peroxyacetyl nitrate (PAN) measurements using gas chromatography with a non-radioactive detector. PAN is a known precursor of ozone. Their method has high accuracy and is more readily deployable in field campaigns than the traditional gas chromatography method that utilizes a radioactive detector.  Read the full paper here.

2 New papers published in October

Two Jaffe Group members have published peer-reviewed papers in October. Well done to Xi Gong and Pao Baylon for their outstanding work!

Xi Gong and her coauthors used a statistical approach, the Generalized Additive Model,  to quantify ozone impacts from wildfires on 8 US cities. They showed that this approach can provide quantitative support for situations when large contributions from noncontrollable sources, such as wildfires, caused an exceedance of the EPA’s daily ozone standard.

Read the full paper here.

Pao Baylon and his coauthors looked at a Siberian biomass burning event in Spring 2015 that was observed at Mt. Bachelor Observatory and by satellite instruments, and also intercepted by a research aircraft. When the plume was in the eastern Pacific, it split into two plumes, one moving eastward toward MBO and the other moving northeast to Alaska and then south to the US Midwest. The second plume was observed by the aircraft in the Midwest. Baylon et al. found that the ozone production observed at MBO was higher than that of the aircraft plume. This was due to the plume at MBO being warmer and the aircraft plume being colder.

Read the full paper here.