Author Archives: dlommers

New post-doctoral fellow openings in Jaffe research group

The Jaffe research team is looking for one or two post-doctoral fellows in Atmospheric Chemistry to join our team!

We have several projects in the coming year that will involve modeling (photochemical box modeling, machine learning/statistical modeling, etc.) and interpretation of large datasets and possibly new measurements (including measurements from low-cost sensors).

  • One project is focused on understanding impacts of smoke on the urban photochemical environment and will use both photochemical box and statistical models.
  • The second project is focused on interpretation of large-scale atmospheric chemistry datasets applied to a variety of scales (e.g., EPA data, NOAA data, Mt. Bachelor observations, low-cost sensor networks, and/or satellite data). We are also working with a variety of low-cost PM and gas sensors, with a particular emphasis on indoor AQ to understand how smoke, cooking, and major freeways impact indoor air.

All skill sets are welcome to apply. We would like to identify a suitable candidate as soon as possible but will consider any student within a year of graduation.

Please forward the linked information to any relevant candidates. Thank you!

Click here for more information.

Free access to paper on fire impacts on air quaility

As part of its Clean Thinking collection, Taylor & Francis is providing free access to a collection of articles on clean thinking for climate change. Included in the collection is the critical review “Wildfire and prescribed burning impacts on air quality in the United States,” published in the Journal of the Air & Waste Management Association in June 2020. Access is free until April 30, 2022.

Read the article

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: PM2.5 (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 PM2.5 and ozone levels isn’t straightforward. He and Jaffe Group researchers have previously found that the most extreme levels of PM2.5 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 (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

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