A Fine Approach for Regulating Fine Particulate Matter

Posted on January 8, 2016 by Todd E. Palmer

The Wisconsin Department of Natural Resources (WDNR) is finalizing guidance documents which will simplify how air permit applicants demonstrate that their emissions do not cause or contribute to exceedances of the PM2.5 National Ambient Air Quality Standards (NAAQS).  This guidance is based upon a technical analysis showing that direct emissions of PM2.5 from most stationary sources do not meaningfully contribute to ambient concentrations of PM2.5.  Building on this conclusion, WDNR will no longer require air dispersion modeling to be performed for PM2.5 when issuing most air permits. This novel state approach to PM2.5 regulation should adopted by other jurisdictions.

As EPA shifts its focus to regulating smaller forms of PM, the chemistry associated with these smaller pollutants has added to the complication of regulation. With respect to PM2.5, it is a pollutant emitted directly by certain emission sources (e.g., combustion processes) and is also formed secondarily in the atmosphere by the chemical interaction of precursor pollutants (NOx, SO2, ammonia). To date, states have generally implemented air permitting policies that simplify these complications. For example, states may assume that a percentage of a source’s PM10emissions consist of PM2.5 or that direct emissions of PM2.5 have the potential to significantly contribute to ambient concentrations of PM2.5. These generalities and assumptions have presented problems for stationary sources, especially when performing the air dispersion modeling attendant to receiving an air permit.

Recognizing these problems, WDNR undertook its own technical analysis which concludes that dispersion modeling of direct PM2.5emissions does not provide information useful for understanding the impact of those emissions on ambient air quality. WDNR found that direct, industrial stationary source PM2.5 emissions do not correlate with the ambient concentrations of PM2.5 in the atmosphere around a stationary source. Rather, PM2.5 exhibits characteristics more like a regional pollutant influenced by the emissions from numerous sources dispersed throughout a broad geographic region. Using this premise, WDNR will be restricting the circumstances when PM2.5 air dispersion modeling will be required when issuing air permits and the instance where sources will be subjected to PM2.5 emission limitations.

In this draft guidance, WDNR proposes to no longer require estimating PM2.5 emissions from fugitive dust sources, mechanical handling systems, grain handling operations or other low temperature PM sources. Rather, PM2.5 emission estimates will only be required for combustion and high temperature industrial processes that directly emit significant amounts of PM2.5.  For these high temperature sources, WDNR will use a “weight of evidence” approach to conclude that direct emissions of PM2.5 do not cause or exacerbate a violation of the PM2.5 NAAQS or increments in ambient air. This will greatly simplify the manner in which air permit applicants must calculate PM2.5 emissions from a project, significantly limit the circumstances in which PM2.5 modeling must be performed as part of a permit application and restrict the instances in which PM2.5 emission limitations must be included in air permits.

Preserving the Tallgrass Prairie in the Face of Stringent Air Quality Standards: The Flint Hills Smoke Management Plan

Posted on January 17, 2011 by Charles Efflandt

It is an environmental truism that increasingly stringent air quality standards can cause collateral damage – typically economic in nature. It is less common for such standards to directly impact preservation of a significant North American ecosystem.

Comprising a vast area in eastern Kansas and northeast Oklahoma, the Flint Hills ecosystem remains today the last unfragmented expanse of tallgrass prairie on the continent. Roughly two-thirds of all tallgrass prairie in North America is contained in the Flint Hills. The Flint Hills provide a unique ecosystem for numerous mammals, birds, reptiles and cattle (the surrogate for the bison that once roamed this area and that served as a keystone species in maintaining biodiversity). The U.S. Fish & Wildlife Service and The Nature Conservancy have both identified the Flint Hills as a priority conservation action site.

Fire is a critical ecological driver in the tallgrass prairie. Lightning is nature’s tool for this process of ecological renewal. The burning of large sections of the Flint Hills was practiced for centuries by Native Americans. In more modern times, controlled burning has been utilized by conservation agencies and organizations, as well as by ranchers, as an ecological and agricultural management tool. Tallgrass prairie preservation requires frequent burning to prevent the encroachment of woody species and maintain the integrity of the plant communities and wildlife habitat. From an agricultural perspective, the burning and renewal of the tallgrass has been shown to significantly increase the productivity of the rangeland for cattle ranching purposes.

Such frequent and widespread burning, however, creates health concerns. Air modeling has shown transport of PM and ozone precursors as far east as Tennessee during the burning season. Air pollutants from Flint Hills burning have also adversely impacted or threatened the NAAQS attainment status of areas in Kansas and Missouri. With more stringent ozone regulations imminent, this conflict between ecological preservation and compliance with air quality standards will be exacerbated.

A recent ACOEL posting suggested, in the climate change context, that the severe economic consequences of the traditional legislative/regulatory process can and should be mitigated through creative voluntary community effort. With the ecologically and agriculturally beneficial practice of tallgrass burning on a collision course with NAAQS attainment, such an approach was recently embraced by the U.S. EPA, Kansas Department of Health and Environment, conservation and agricultural organizations and academia. The December 2010 approval of the Flint Hills Smoke Management Plan was the result of over a year of collaborative effort by these stakeholders. The key elements of the Plan include:

  • A new website with a predictive plume modeling tool for public and private decision-making.
  • Development of fire management practices to mitigate adverse health consequences and NAAQS violations associated with controlled burning.
  • A comprehensive data collection effort to better characterize prairie burning and its consequences.
  • Proposed limited legal restrictions on open burning during critical time periods.
  • Extensive outreach and education efforts, including prescribed fire training programs, public-private information sharing, and media exposure.
  • A pilot project in the spring of 2011 in two Kansas counties to implement the predictive computer modeling and fire management practices.

The Plan has been attacked by certain environmental organizations as a “smoke screen” whose objective is to facilitate EPA exemption of burning from enforcement in order to maximize beef production. These critics discount the ecological motivation for the Plan and allege that it is unlikely to adequately protect public health. I would suggest that the Plan should not be viewed as the final answer. Rather, it should be considered a working document that will evolve as the results of modeling and data collection and level of voluntary implementation are evaluated. Time will tell the extent to which the Plan can be cited as further evidence of the power of voluntary, collaborative