Ashes to ashes

The EPA’s new air pollution rule may make mines go bust.

By Russ Randle

The Environmental Protection Agency (EPA) is currently considering revisions to the National Ambient Air Quality Standard (NAAQS) for particulate matter. That change may be proposed in early 2011, and the revisions may make it much more costly and difficult for mines and mills to operate. The bottom line is to pay close attention as these standards are developed and to submit solid data to support distinctions between urban and rural particulate; as well as data showing how much particulate pollution arises from natural and out-of-state sources. These data may help avoid needlessly draconian standards.

Section 109 of the Clean Air Act, adopted in 1970, tells EPA to set NAAQS at levels “the attainment and maintenance of which in the judgment of the Administrator. . . allowing an adequate margin of safety are requisite to protect the public health.” EPA is required to update the standards every five years. The courts have repeatedly held that setting these standards is strictly a public health judgment; the economic and technical feasibility of attaining the standard are not to be considered at this stage. Those feasibility factors are to be considered, if at all, when the air quality standard is translated into specific emission limits for each source.

Starting in the 1980s, EPA changed the standard’s focus from total suspended particulate (TSP) to smaller particulate and changed the standard to one controlling particulate matter smaller than 10 microns in size (PM10), because these posed the greatest health threat. EPA has since refined this understanding further with a separate standard for particulate matter smaller than 2.5 microns in size (PM2.5). Unfortunately, the monitoring network is not yet extensive enough to allow easy correlations between PM2.5 and PM10 concentrations and different medical results.

EPA will be making choices about revised PM10 and PM2.5 standards, and the agency has to decide not only the allowable concentration of different size particulates in the air, but also the proper averaging time for compliance (e.g. three hours), the number of allowable exceedances over time (e.g. one every three years), and whether the division into different size particles continues to make sense. EPA is discussing a range of changes, but the practical effect of most of them will be to make the standard much more stringent.

As more stringent NAAQS for particulates are translated into more stringent emission limitations for specific sources, mines and milling operations will almost certainly face costly choices — even though compliance problems in that vicinity may be outside their control. This problem is especially true for those who operate in arid, naturally dusty parts of the United States. These problems may include the following:

1. Fugitive dust. Most of the western United States is arid, and windblown dust is common. Although this dust is less dangerous to people than urban particulate from combustion sources, the courts have rejected EPA’s past efforts to distinguish between urban and rural particulates. Thus, the air may be dusty from natural causes, but contribute to a compliance problem.

2. Interstate and international pollution transport. Weather systems do not respect national — or state — boundaries. Since the 1990 Clean Air Act was passed, Chinese dust storms have measurably affected local air quality in the United States, and Canadian forest fires have visibly affected air quality as far south as Virginia. Similarly, upwind U.S. states contribute to the fine particulate load at downwind states, a serious problem in much of the eastern half of the United States. EPA is trying to address that problem in the Clean Air Transport Rule (CATR), which will impose additional controls on sulfur dioxide emissions from electric generating units in more than 30 states, mostly east of the 100th meridian. The data suggest that such transport will make it harder for downwind sources to comply.