U.S. EPA's final air quality standard for nitrogen dioxide (NO2) entails new requirements for measuring peak exposures near roads, but it would monitor fewer roadside locations than the agency's original proposal.
The health-based NO2 standard issued Monday introduces a new one-hour maximum standard for NO2 at 100 parts per billion (ppb), which EPA says will protect millions of Americans from peak short-term exposures. Because short-term exposures to NO2 occur primarily near major roads, the standard also requires new monitors to be placed along major roadways in some urban areas (Greenwire, Jan. 25).
EPA's initial proposal required urban areas with more than 350,000 people to install at least one monitor near a major road, which would have mandated about 167 roadside monitors in about 142 urban areas. But the final rule raises that threshold to 500,000 people, requiring about 126 new monitors along roads in 102 urban areas.
Environmental and public health advocates are concerned about EPA's decision to monitor pollution along fewer roads, while state and local air regulators are urging the agency to start off with an even smaller roadside network until questions about costs and implementation have been answered.
Debbie Shprentz, a consultant to the American Lung Association, said the change means that "people in communities with less than half a million people may be left unprotected."
Monitoring pollution along congested roadways is particularly important, said Clean Air Watch President Frank O'Donnell, because that's often where the highest concentrations of pollutants are found.
"By itself, the standard is not going to create anything unless the new monitoring system triggers areas that are out of compliance," O'Donnell added.
Under EPA's latest monitoring data, Chicago is the only large metropolitan area in the United States to consistently violate the new NO2 standard (Greenwire, Jan. 26).
EPA changed the threshold after considering a range of public comments, including those from state groups concerned about funding, problems with state implementation plans that target major roadways and other issues, according to the rule.
Administrator Lisa Jackson concluded that using the 500,000 threshold provides a sufficient network of roadside monitors that supports the intent of the revised standard and continues to meet the monitoring objectives of the network, EPA said in the final rule.
Areas with populations of 350,000 or more contain about 71 percent of the total U.S. population, EPA said, while areas with 500,000 or more contain about 66 percent of the population.
EPA also stipulated in the final rule that regional agency chiefs have the authority to site 40 additional monitors in whatever areas they deem necessary to protect vulnerable communities, meaning that the total numbers of monitors in the proposed and final rules are generally equivalent.
Bill Becker, executive director of the National Association of Clean Air Agencies, said that while state and local air regulators support a robust monitoring network, "It will not be easy near roadways to administer a comprehensive monitoring network and obtain results that will be easily understood."
Air regulators are also concerned about whether they will have sufficient federal funding to purchase and run the monitors, Becker said, adding that the capital and maintenance costs "will be far more than what EPA suggests."
Becker said his group is advocating a small initial network of five to 10 near-road monitors to determine the best course of action, including defining the ultimate size and location of the network.
White House role?
Environmental and public health advocates are also concerned about possible White House influence over the thresholds. An e-mail dated Jan. 18 from an EPA air quality official to an official in the White House Office of Management and Budget indicates that OMB was involved in discussions about the roadside monitoring requirements the week before the final rule was issued.
"There's a negotiation going on between EPA and OMB. We don't know what else was on the table, but we know that this change occurred," Shprentz said.
EPA spokeswoman Adora Andy declined to specify what role OMB played in the deliberations, saying, "The new one-hour standard for nitrogen dioxide resulted from a successful deliberative process and will yield a far greater level of monitoring and protection than ever before."
Becker said that White House officials did not discuss the matter with his group, but added, "OMB understands the funding implications of this, and by raising the threshold, they were able to require less monitors than they otherwise would."