New Ozone Standards Present Challenge, Opportunity for D.C. and Other U.S. Regions
Ozone alert in Fort Worth, Tex. Photo by haunted by Leonard Cohen.

Ozone alert in Fort Worth, Texas. Photo by haunted by Leonard Cohen.

Clean air is a fundamental part of our quality of life, a part which has undoubtedly improved since the passage of the Clean Air Act.  Especially during the summer, we are often reminded of remaining air quality issues, with radio stations notifying listeners of “code orange” days.  Orange means the air is unhealthy for sensitive groups.  In the D.C. region, we’ve had nine “orange” days in the month of June, 10 “green” days (good air quality) and 11 “yellow” days (moderate air quality.)  Moving into July, we’ve already experienced several more “orange” days, and one “red” day (unhealthy). You can find this information for the D.C. metro area here, and for other regions of the U.S. here.

A region’s reported air quality corresponds to the concentration of “criteria” pollutants in the atmosphere, including particulate matter, lead, carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOX), and ground-level ozone (O3), which is the principal component of smog.  Ozone, in particular, is receiving renewed attention due to recent proposals by the U.S. Environmental Protection Agency to establish stricter ozone standards, which will be finalized in August. The proposed ozone rule could have a big impact on transportation. 


The EPA proposal would bring the 8-hour primary ozone standard to within 0.060 to 0.070 parts per million (ppm), meaning that that 8-hour average concentrations of ozone are not to exceed that level.  By law, these national air quality standards must be determined on the basis of public health and environmental quality – not economic considerations.  Still, it is worth noting that the potential human health and welfare benefits are in the tens of billions of dollars, and may exceed the economic costs of compliance, according to official benefit-cost analysis of the new ozone standard.  Moreover, the new standards will save thousands of additional lives.


The proposed 2010 standard would not take full affect until 2014.  The map below shows which counties in the D.C. region would not be meeting the new standard if it were in in effect now (D.C. is the dark blue diamond about 1/3 down from the top).  The EPA also provides a national map showing the regions designated as “non-attainment” and “maintenance” areas relative to the 1997 ground-level ozone standard (0.085 ppm, which has been in effect for the past several years).

Source: Metropolitan Washington Air Quality Committee (MWAQC), January 2010

Source: Metropolitan Washington Air Quality Committee (MWAQC), January 2010

The D.C. region and many other regions will face many challenges, based on local background concentrations of ozone, weather conditions that contribute to ground-level ozone formation (sunlight and stagnant air) and pollution from various sources and sectors.  Emissions inventories vary significantly between regions.  Regions across the U.S. have had varying degrees of success in meeting the existing standards and some regions have virtually exhausted certain mitigation measures for various sectors.


Compliance with the standards for ground-level ozone and other criteria pollutants is an important aspect of regional transportation planning in the United States.  EPA’s proposal to tighten these standards is already prompting some states and regions to consider what actions may be needed in transportation and other sectors to ensure they’ll be able to comply with this standard over the course of the coming decades.

Regions designated as having non-attainment or maintenance status under the Clean Air Act standards are required to demonstrate that transportation investments are consistent with mobile source emissions projected in state air quality plans.  Failure to produce plans that effectively demonstrate how satisfactory reductions in criteria pollutant emissions will be achieved can lead to suspension of federal transportation funding.  Federal transportation funds have rarely been withheld except for a few instances. For example, restrictions on transportation funding in Atlanta during the late 1990s gave rise to an excellent smart growth development project, Atlantic Station.  Occupying the site of the Atlantic Steel Company, which employed 2,000 people before closing in 1998, the Atlantic Station mixed residential and commercial development has accommodated 3,000 new residents and 3,500 jobs in the central city, all without adding a lot of traffic to the region.  A recent report on the environmental impacts of the redevelopment project finds that 42% of trips to, from and within the site are something other than “drive alone” trips, and that residents of Atlantic Station drive only 32%-43% as much as the regional average.


Transportation strategies to reduce ground level ozone levels include technological advances as well as urban and regional planning strategies that moderate traffic growth – as seen in Atlantic Station. Ozone is not directly emitted, but is formed in the presence of NOx and volatile organic compounds (VOC).  Reducing emissions of NOx and VOC effectively reduces ground-level ozone.  Since the early ’70s, several relatively easy to deploy technologies like catalytic converters and low sulfur fuels have significantly reduced NOx and VOC emissions from automobiles.  These technologies have reduced smog, diminishing (or at least deferring) the need to address personal travel behavior. However these technological solutions for typical cars and trucks have already run their course in many regions, and technological prospects for further NOx and VOC reductions are limited unless we expect a rapid conversion of the vehicle fleet to extremely low or zero-emissions vehicles. So it may be that more regions will now pursue transportation strategies to moderate traffic and vehicle travel demand.

Metropolitan Washington Council of Government’s 2007 Air Quality Plan for the Washington, D.C. region reveals that vehicles are the largest source of both NOx and VOC emissions, even considering recent progress (predominantly via technological measures) that reduced these emissions by an estimated 45% and 42%, respectively, between 2002 and 2009. Utilities are the next highest source of NOx emissions, and lawn and garden equipment and various area source categories are other substantial sources of VOC emissions.  Top sources of emissions do vary from region to region. For example, while two major ports in Los Angeles receive about 40% of the nation’s containerized cargo, the L.A. region’s air quality management plan lists ocean-going vessels, heavy duty vehicles, off-road equipment and light duty cars and trucks among the highest sources of the region’s NOx emissions.


While technological advances will continue to be important in reducing NOx and VOC emissions in many sectors, strategic approaches that influence behavior for the better should also be included in emissions reductions plans.  Regions that that face non-attainment on account of emissions from cars and light trucks should consider strategic and comprehensive planning efforts to reduce traffic by facilitating alternative modes of travel (transit, walking, biking, carpooling, even telecommuting), which can create a virtuous cycle of public health benefits through improved activity levels, reduced obesity and lower levels of chronic disease. The Atlantic Station development shows that innovative projects can emerge amidst the challenges presented by federal air quality regulations.  While EPA’s new standard will be seen as a challenge by many regions, it is also an opportunity to re-align our regional priorities towards public health, time savings, reduced congestion and a better quality of life. Here’s hoping for many “code green” good air quality days ahead.

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