For the first time in over 35 years, the U.S. Environmental Protection Agency (EPA) has proposed changes to the national ambient air quality standard (NAAQS) for nitrogen dioxide (NO2). NAAQS define the maximum allowable level of pollutants and drive state air pollution cleanup programs. EPA has proposed adding a new one-hour standard to the existing annual standard. EPA also proposes to establish a roadside monitoring network to track peak levels of NO2 along major highways. AGC is analyzing what a new NAAQS for NO2 may mean for future construction, including new stricter requirements and/or restrictions on diesel engines and their use.
EPA must set its final rule for NO2 air quality by January 22, 2010. NO2 serves as the indicator for the entire family of nitrogen oxides; diesel engines emit NOx (mono-nitrogen oxides). Diesel experts say that a tighter NAAQS for NO2 could impact diesel engine users in the following ways:
- Trigger federally enforced clean-up measures and additional stress on state and local air quality planning. If EPA ratchets down the standard (allowingless NO2 in the air), many states may need to reduce their sources of NO2 to stay in attainment of the new federal air standards. (Currently, California is the only state that has ever had NO2 nonattainment areas.) States are responsible for preparing and executing state implementation plans (SIPs) to achieve and maintain NAAQS within their borders. As part of the SIP, states may enact and enforce requirements that affect the business of construction. (What is more, states that fail to develop suitable SIPs could be subject to numerous federal sanctions, including emissions caps limiting economic development and the loss of federal highway transportation funds.)
- Potential for more stringent new diesel engine emission standards for NOx. The proposed rule discusses all the progress made across the board for diesel engines, which seems to suggest that EPA is not thinking about proposinglower NOx standards for diesel engines of any kind. Still, more stringent new diesel engine emission standards for NOx area possible consequence of tighter NO2 standards. (NOTE: If EPA's NO2 proposal goes final, the "official" designations for attainment and non-attainment will not occur until 2012 - with the first compliance dates coming in the year 2022, at the earliest. At that point, a substantial number of the unregulated Tier 0 (high NOx emitting) equipment may be retired.)
- Establishment of a roadside monitoring network to identify where NO2 levels are the highest and requirements to monitor the effectiveness of control measures. The proposed rule puts a lot of emphasis on "hot-spots" and, in particular, concentrations of NO2 near roadways. Specifically, EPA is proposing specific minimum requirements to guide placement of new NO2 monitors, including a condition that at least one monitor be located near a major roadway in any urban area with a population greater than or equal to 350,000 people. That could mean more state measures to reduce NOx emissions from in-use diesel vehicles and equipment. This could trigger restrictions on how contractors use and operate their construction equipment, as well as early retirement and/or retrofit requirements.
- Restrictions on future transportation planning and programs. Transportation and traffic is one of the biggest contributors of NO2, according to environmentalists' reports. If EPA sets new more stringent standards for NO2, it will certainly impact transportation planning and programs in the future. Transportation conformity (a Clean Air Act process that requires coordination of transportation and air quality planning) applies to all ozone, carbon monoxide, particulate matter and NO2 nonattainment and maintenance areas, regardless of classification. When an area is out of conformity, meaning the projected motor vehicle emission in the transportation planning documents (TIP) do not stay within the budgets set by the air quality planning documents (SIP), the funding and implementation of all federal highway/transit projects in the nonattainment area are suspended.