Author Archives: dlommers

Wildfires and poor air quality—Is this the new normal?

When smoke gets in your eyes this summer, your thoughts are probably turning to wildfires. Wildfires are on nearly everyone’s mind these days in the Pacific Northwest because of the smoky haze and poor air quality that is blanketing our area. This August is similar to August 2017, and so you might wonder—why is this happening and is it going to continue? Those are the questions many reporters have been asking Dan Jaffe in the last few weeks.

A new paper by group members Crystal McClure and Dan Jaffe published in the Proceedings of the National Academy of Science addresses these questions. This research highlights the dramatic gains in air quality that have taken place in the last few decades around the country except in the Northwest. In this region, the 98th percentile of daily fine particulate matter (PM2.5), or in other words the seven worst air quality days each year, is getting worse. Around the US, there have been improvements in air quality from reduced power plant, industry, and automobile emissions, but in the Northwest, those reductions are outweighed by the emissions from wildfires. Learn more about this paper.

The indications are that the wildfire season will continue to get worse in the Northwest. Forest management practices and meteorological factors such as increased spring and summer temperatures, earlier snowmelt, and dryer forest conditions contribute to the current situation. “We want to be careful not to put it all on climate change, but climate change is clearly a contributing factor, and particularly in the size of these fires,” Dan Jaffe told E&E News. “A fire that used to become a small fire has now become a massive conflagration.” We will see more high fire years and, in general, longer fire seasons and bigger fires.

The increase in wildfires and smoky conditions causes adverse health effects. Wildfires are a major source of fine particulate matter, which is small enough to be inhaled deeply into the lungs. The health impacts of breathing smoke can be significant, especially for children, the elderly, and people with pulmonary, cardiovascular, and other chronic conditions.

To listen and watch interviews with Dan Jaffe about wildfires and air quality, visit:

To read more, see:

To see all news reports and articles about our research, see our In the News page.

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

Court decision on Oakland coal terminal

An article in the East Bay Express discusses the court decision on the coal export terminal that developers propose to build near the foot of the Bay Bridge in Oakland. Earlier this year, a U.S. District Court judge overturned Oakland’s ban on storing and handling coal at this planned marine terminal. Judge Chhabria found that there wasn’t enough evidence to support Oakland City Council’s assertion that “the proposed coal operations would pose a substantial danger to people in Oakland.” ESA, an environmental consulting firm, helped the city study the possible environmental impacts of shipping coal by train to the terminal. They found the scientific research on coal dust emissions from trains extremely lacking. In fact, they could find only one recent, peer-reviewed scientific study focusing on coal dust emissions from trains: the 2014 Jaffe Group paper “Diesel particulate matter and coal dust from trains in the Columbia River Gorge, Washington State, USA.”  Judge Chhabria agreed with the city that some level of coal dust pollution is likely but said that the city couldn’t show exactly how much and what the health and safety impacts would be. Scientific research on the effects of coal dust emissions on public health in urban areas is limited. Oakland is currently appealing the court’s decision.

Read the East Bay Express news article here

Postdoctoral Research Associate openings

The Jaffe Research Group has openings for 1–2 postdoctoral fellows who will focus on understanding gas and aerosol chemistry from global and regional sources.

  • One position will focus on collecting and interpreting observations from the Mt. Bachelor Observatory (MBO), an NSF-funded observatory that we have operated since 2004. MBO measures a suite of key gases and aerosol components (e.g.,O3, CO, CO2, σscat, σabs) year round. During spring and summer intensives, additional measurements (NOx, NOy, VOCs, aerosol chemistry, and physics) are added to focus on specific research questions.
  • The second position will study O3, NOx, and VOC chemistry in wildfire plumes as part of the NOAA FIREX campaign.

The primary responsibilities for these positions include:

  • Making high quality observations of atmospheric constituents.
  • Interpretation of the data with other observations, such as meteorology, regional air quality, satellite data, and air quality models.
  • Publishing the results in top scientific journals.

Qualifications include:

  • PhD in Chemistry, Atmospheric Sciences, Geosciences, or a closely related field.
  • Strong expertise in one or more of the following areas: instrumentation for gas and aerosol measurements (especially VOCs by GCMS), data interpretation, integration of satellite data, and modeling of transport and chemistry.
  • Good communication skills and experience publishing in scientific journals.

Appointments will be for one year with possible extensions. Compensation is competitive and post docs receive a full benefits package.

To apply and to see the full position description, see For more information, contact Dan Jaffe at

The positions are available immediately and will remain open until filled.

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: