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Another Study Shows Why Background Ozone Makes Meeting EPA Ozone Standard Difficult for Western States


A new study out this month provides more evidence of the challenges of background ozone, which make it nearly impossible for western states to meet the Environmental Protection Agency’s 2015 ozone standard.

The study, published in the Journal of Atmospheric Chemistry and Physics, concluded that background ozone, including air pollution from Asia, is undermining ozone reduction efforts in the United States. This deduction points to something that many western air regulators already know- western states will simply be unable to comply with the 2015 ozone standard due to factors beyond their control.

In the researchers own words:

“Asian NOx emissions have tripled since 1990, contributing as much as 65% to modeled springtime background O3 increases…over the [western U.S. (WUS)], outpacing O3 decreases attained via 50% US NOx emission controls…During summer, increasing Asian emissions approximately offset the benefits of US emission reductions, leading to weak or insignificant observed O3 trends at WUS rural sites.”

They go on to note that these factors have been identified over and over again as impacting the western United States’ ability to comply with Federal ozone NAAQs:

“There are concerns that rising Asian emissions and global methane (Jacob et al., 1999; Lin et al., 2015b), more frequent large wildfires in summer (e.g., Jaffe, 2011; Yang et al., 2015; Abatzoglou et al., 2016), and late spring deep stratospheric O3 intrusions (Lin et al., 2012a, 2015a; Langford et al., 2014) may pose challenges in attaining more stringent O3 standards in high-elevation WUS regions.”

NASA’s Jet Propulsion Center also reached this conclusion in its August 2015 study, which asserted that a “combination of naturally occurring atmospheric processes and pollutants crossing the Pacific Ocean from China” have resulted in smaller than expected decreases in ozone levels in the western United States. Other studies have gone so far as to recommend that the next time EPA revisits ozone NAAQS, that their evaluation include “consideration of the large enhancement from anthropogenic emissions outside North America.” This is an especially salient recommendation given the fact, by EPA’s own calculations, emissions in East and South Asia “are expected to continue to increase.”

Despite these studies and CRS’s repeated warnings that background ozone will make compliance impossible for some states, EPA finalized an ozone rule that punishes western states for China’s pollution.

Background Ozone Raised As a Challenge by Western States and Stakeholders

The evidence on background has been mounting for so long that even Democratic Senators, Governors, State Senators and air regulators have pushed back on the EPA’s 2015 ozone standard.

In Colorado alone, both Democratic U.S. Senator Michael Bennet and Democratic Governor John Hickenlooper have expressed deep concern over what stricter ozone rules will mean for Colorado’s economy and whether or not it’s even possible for the state to reach the standard. Senator Bennet even characterized the regulation as “a perfect example of applying the law but doing it in a way that doesn’t make sense on the ground.”

Similarly, Colorado State Senator Cheri Jahn (D-Wheat Ridge) stated:

“This whole situation is a mess. EPA officials did an abysmal job with the prior standard of 75 ppb, set in 2008. Instead of working with states to implement those ozone rules, they have been obsessed with changing the rules until they are completely unworkable.

“Even the EPA admits the new standard of 70 ppb is practically impossible for Denver to meet, because of background ozone that we can’t control. Now we are facing long-term violation of the new standard, which will impose all kinds of new controls and restrictions on the economy, small businesses and investments in transportation infrastructure. EPA officials have claimed they will develop a fix for the background ozone issue, but they should have worked all that out before setting the new standard in the first place.”

The Western States Air Resources Council (WESTAR,) a Seattle-based group representing 15 air quality regulatory agencies from many Western states including Colorado, has also sounded the alarm over background ozone levels that are beyond the control of local officials, particularly those sources that originate in “Mexico, Canada, or Asia.” In fact, even EPA had to admit in a white paper it quietly published in December of 2015 that Denver cannot reach new standard until 2025 because of background ozone.

In our own in depth analysis of the impact of the 2015 ozone standard on Colorado counties, CRS spoke to many more local stakeholders; from construction firms to county commissioners to local editorial boards, all saying the same thing, the unattainable 2015 ozone standard is setting Colorado up to fail.

A Bipartisan Washington Solution Coming Soon?

The good news is that since so many Democrats and Republicans agree the 2015 standard is so unworkable, there is the possibility for a legislative solution.

Just last week, Senator Jeff Flake (R-AZ) reintroduced two bills aimed at reining in the economic impact of the EPA’s 2015 standard by ensuring states and localities are not held responsible for uncontrollable, naturally occurring events that affect their air quality (like international transport and wildfires). The second of these two bills also proposes revising EPA’s existing timeline for NAAQS review from every five years to every 10 and delaying the implementation of the 2015 ozone standard to 2025.

CRS’ supports these legislative solutions and views them as an effective means to protect small businesses across the country from expensive and unnecessary ozone regulations.

About CRS

The Center for Regulatory Solutions is a project of the Small Business and Entrepreneurship Council, a 501c(4) advocacy, research, education and networking organization dedicated to protecting small business and promoting entrepreneurship. For twenty-three years, SBE Council has worked to educate elected officials, policymakers, business leaders and the public about policies that enable business start-up and growth.