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No Change in EPA NO2 and SO2 Secondary Standards

EPA last Wednesday, March 21st, issued a final determination to hold two air standards at existing levels – one for nitrogen dioxide (“NO2″) and one for sulfur dioxide (“SO2″).  The two standards are referred to as “secondary standards” because, unlike “primary standards,” they are not intended for the protection of human health.  Instead, they are designed to “protect the public welfare,” which has been defined in the Clean Air Act as the protection of “soils, water, crops, vegetation, man-made materials, wildlife, weather, visibility and climate,” among other things.  In particular, EPA has been working to design NO2 and SO2 secondary standards to protect sensitive ecosystems from acid rain or dry acid deposition.  Acid deposition has been greatly reduced over the past few decades following the adoption of the Title IV Acid Rain Program under the Clean Air Act, but EPA scientists have recently claimed that new, more stringent secondary NO2 and SO2 standards, are needed to provide additional protection against acid-related welfare effects.

Until two years ago, both the primary and secondary standards for NO2 and SO2 remained at levels initially established for those pollutants in 1971.  However, in 2010, EPA established new primary standards for NO2 and SO2 that are generally viewed as some of the most stringent air quality standards ever adopted.  At the same time, EPA indicated an intent to revise the secondary standards as well, suggesting that perhaps the secondary standards should at a minimum be established at the same level as the new primary standards.  However, the announcement on Wednesday indicates that the secondary standards will remain constant for at least five more years until the next periodic review required by the Clean Air Act.

Even though EPA chose to leave the secondary standards constant for the time being, EPA still issued a formal rule to announce its decision, in part to satisfy a court-ordered consent decree, but also in part to further explain its decision.  In short, the rule indicates that EPA agrees the current secondary standards are insufficient to protect public welfare from acid deposition-related impacts, conceding that the current standards are not “ecologically relevant.”  Nevertheless, EPA concluded that the science is not yet sufficiently developed to develop new, more protective standards because of a number of uncertainties.  Specifically, EPA has developed a new method for determining an appropriate standard to protect against acidification, but the factors that underlie that analysis remain untested.  Thus, despite EPA’s admission that current standards are inadequate, more stringent standards must await further study.

Environmentalists criticized the decision as reminiscent of EPA’s decision last year not to move forward at that time with more stringent ozone standards.  The Obama Administration directed EPA to leave the national standard for ground-level ozone constant, instead of strengthening it as demanded by various environmental groups and recommended by EPA staff.  Because the decision came from the Executive Office of the President, rather than from within EPA itself, many environmentalists decried the move as politically-motivated.  The decision to hold the NO2 and SO2 secondary standards constant has once again prompted various environmental organizations to cry foul and complain that political forces are inappropriately influencing the country’s environmental policy.