Air quality in Eugene

Why is Eugene air quality bad?

When it comes to clean air, short-term particle pollution (PM2.5) is of primary concern in Eugene, Oregon. Eugene averages 6.2 unhealthy PM2.5 days per year, nearly double the federal allowance set at 3.2 unhealthy days per year.¹

PM2.5 includes a combination of airborne particulate matter including ash, soot, dust, dirt, pollen, and chemicals that measure 2.5 microns in diameter or smaller. Unlike gases and other commonly measured air pollutants, PM2.5 is defined by its size rather than its chemical makeup. This is because PM2.5 describes matter so small that it’s able to cross the natural barriers in our airways and enter the bloodstream. In doing so, PM2.5 has the ability to affect a variety of organs, such as the heart and brain, among others.

PM2.5 pollution in Eugene comes from a combination of sources including vehicular and industrial emissions, wood and stubble burning, windblown dust and pesticides from agricultural land, pollen from the Willamette Valley grass seed farms, and transboundary pollution carried by wind from neighboring cities and states.²

To understand Eugene air quality, it’s important to understand the difference between air pollution emissions and measured air quality levels. While emissions are responsible for polluting the air with particles and gases, meteorological events such as wind, rain, and temperature conditions can significantly impact measured ambient air quality. This is because weather plays a critical role in pollution dispersion. While wind and rain, for example, can disperse and tamp down particle pollution, a lack thereof can cause emissions to accumulate. Temperature conditions can likewise play a similar role.

Under normal thermal conditions, temperatures decrease with gains in altitude. Thermal, or temperature, inversions occur when these conditions are disrupted. For example, when ground-level air is cooler than an air layer directly above it. When this happens, the cool ground-level air stagnates and is prevented from rising and dispersing, causing ground-level pollution emissions to accumulate. Thermal inversions in inland Oregon are particularly common during the winter when snow coverage, freezing conditions, and a lack of direct sunlight contribute to freezing ground-level air.

In Eugene, PM2.5 emissions tend to reach their highest levels during wildfire season in the late summer, early fall, and in the winter as a result of domestic wood burning. In 2019, November and December were Eugene’s most polluted months respectively, with PM2.5 concentrations of 21.7 μg/m³ and 16.8 μg/m³, roughly 4 to 5 times summer levels. These high measured values are largely attributable to climatic conditions that trap emissions in the atmosphere rather than the increase in direct emissions.

Denver air quality suffers from similar climatic conditions. Both cities tied at #24 for worst short-term air pollution in the US out of 201 included cities according to the American Lung Association’s (ALA) 2018 State of the Air report.

Of neighboring cities, Eugene reported the highest PM2.5 levels in 2019 with an average annual concentration of 8.8 μg/m³, but fared better than neighboring interior cities, such as Salem and Roseburg, in 2018, with a PM2.5 concentration of 7.1 μg/m³. Other cities reported:

• Portland air quality (103 miles away): 8.1 μg/m³ in 2019, 6.9 μg/m³ in 2018
• Roseburg air quality (60 miles away): 7.3 μg/m³ in 2019, 8.4 μg/m³ in 2018
• Salem air quality (61 miles away): 7.2 μg/m³ in 2019, 7.8 μg/m³ in 2018
• Albany air quality (40 miles away): 6 μg/m³ in 2019, 6.5 μg/m³ in 2018

While short-term PM2.5 pollution is the only measure for which Eugene air quality fails to meet US Environmental Protection Agency (EPA) attainment, other pollution measures have room for improvement as well.

The ALA grades cities based on their ability to meet targets for short-term pollution. Standards are set by the US EPA, recommending an allowance of no more than 3.2 unhealthy pollution days per year. In 2020, the ALA graded Eugene a “C” for ozone, for passing the federal target, while still reporting an average of 1.7 unhealthy ozone days per year.

Is air pollution in Eugene getting worse?

In terms of deadly PM2.5 and ozone pollution, Eugene air quality has improved significantly over the last two decades. Overall improvements owe to regulations on woodburning and highly polluting industries as well as a transition to a cleaner energy power grid portfolio and lower-emission, more fuel-efficient vehicles, among others.

After particularly long and severe wildfire seasons in 2017, 2018, and 2020 (all of which were at one-point, record-breaking), observers may feel like pollution is in fact getting worse. They are not wrong. From 2007 to 2016, Lane County met federal attainment levels for short-term PM2.5. Since 2016, however, there has been a rise in particle pollution events largely correlated with the wildfire season.

In 2020, wildfire smoke contributed to the highest air quality levels on record for Lane County (AQI 494) since its monitoring began in 1968.³ The last record was set on September 3, 2017 as a result of the Deception Complex Fire, which caused Eugene’s AQI to reach a value of 291.

While more frequent and severe wildfires present a challenge in maintaining clean air, the city has made significant achievements in the last 20 years, such as meeting federal attainment for annual PM2.5 and daily ozone pollution. Continued efforts can even further reduce the potential for resident health implications.

How is air quality in Eugene Oregon fire season?

Oregon wildfires tend to be ignited either naturally, by lightning, or by human negligence, such as poorly discarded cigarettes, campfires, acts of arson, and misfired fireworks. While fires are possible every month of the year, Oregon’s wildfire season usually begins in early July and extends through late September.⁴ Fires that occur in the early and late end of the season are often human-caused, while peak fire months (late July, August, and early September) are more often associated with lightning sieges.

Seasonal trends, impacted by climate change, have led to earlier snow melts, drier summer conditions, warmer temperatures, and an increase in dead forest underbrush — all of which contribute to worsened wildfire seasons. Eugene air quality suffers as a result.

2020 was a record wildfire year in Oregon, and directly contributed to record air pollution in Eugene. For the first time, since records began in 1968, air quality in Eugene exceeded an AQI of 300, “hazardous”. Moreover, unhealthy air quality levels were sustained for more than a week.

There is not always such a clear correlation with wildfires and Eugene air quality. Weather, such as wind, rain, and temperature conditions, dictate whether pollution disperses freely or becomes trapped in the atmosphere. Follow forecast air quality data in Eugene to understand how these effects are likely to affect city-wide air quality on any given day.

Where is smoke in Eugene coming from?

When Eugene air quality suffers from smoky skies, it is usually the result of wildfires burning in the region. Record Oregon wildfires have kept the topic of air quality in news headlines, recent smoke causes cities to experience days and weeks of “unhealthy” air quality.

Environmental scientists attribute the increase in wildfire frequency and severity to anthropogenic, human-caused climate change.⁵ In the last two decades, nearly every year has been classified as having “severe drought” conditions – only 4 years escaped having this title. During the same time period, temperatures in the US northwest have risen by 1.5 degrees Fahrenheit on average.

As wildfires and smoky skies become part of the new norm during the months of July through September, it will become increasingly important for residents to take action to reduce their pollution exposure.

The IQAir air quality map of Eugene, Oregon provides real-time fire and air quality data, allowing users to pinpoint where fires are burning and observe how these emissions are affecting air quality. Use the air quality forecast to help anticipate spells of polluted air and guide precautions.

What is Eugene doing to improve air quality?

Eugene has been successful in driving down daily city-wide emission through a multi-pronged approach, including a general shift towards renewable electric energy, higher efficiency requirements, and regulations on high-emitting industries. The two single most impactful changes have come by-way of renewable energy, and ongoing efforts to transition residents to electric vehicles.

Renewable Electric Energy

Eugene benefits from one of the cleanest power grid portfolios in the nation.⁶ Roughly 80 percent of Eugene’s power is sourced from carbon-free, air pollution-free hydroelectric energy. The remaining 20 percent, meanwhile, is sourced from more conventional renewable sources. Almost no energy comes from fossil fuels. By eliminating coal-fired power plants and shifting to renewable sources Eugene ranks as one of the top 100 cleanest power cities in the world.

Electric Vehicle Incentives

Motor vehicles are traditionally the single largest source of air pollution in US cities, contributing to deadly ambient PM2.5 and ozone. Hybrid and electric vehicles offer an opportunity for driving down emission from this sector. Oregon is promoting the adaptation of electric vehicles through rebate programs which can save buyers as much as $5,000.⁷ The federal government offers an additional tax incentive, which may credit new buyers as much as $7,500. The federal tax credit is currently only available to the first 200,000 eligible vehicles per manufacturer.

+Article Resources

[1] American Lung Association. (2020). State of the Air – 2020.
[2] Houston H. (2018, July 19). It ain’t easy being wheezy. Eugene Weekly.
[3] Parafiniuk-Talesnick T. (2020, September 14). 'We've never seen this before': Smoky air expected to continue to plague Lane County residents this week. The Register-Guard.
[4] City of Eugene. (2020). Emergency management - wildfire.
[5] Burns J. (2020). We know climate change set the conditions for Oregon fires. Did it stoke the flames, too? Oregon Public Broadcasting (OPB).
[6] Eugene Water & Electric Board. (2020). Where your power comes from - power supply.
[7] Eugene Water & Electric Board. (2020). EV incentives and rebates.