In National Farm Bureau Federation v. EPA, the D.C. Circuit Court of Appeals has granted environmental group petition for review of the NAAQS for fine particle pollution known as PM 2.5. Environmental groups and industry groups both challenged portions of EPA’s standard. The EPA had decided to maintain the annual standard at 15 μg/m3. The Court concluded the EPA lacked a valid scientific basis to support their decision:
We conclude the EPA failed adequately to explain why, in
view of the risks posed by short-term exposures and the
evidence of morbidity resulting from long-term exposures, its
annual standard is sufficient “to protect the public health [with]
an adequate margin of safety,”
We conclude the EPA has failed reasonably to explain why
it believes its daily standard will “provide an appropriate degree
of protection from health effects associated with short-term
exposures to PM2.5.” Id. at 61,174/3. We therefore remand the
annual standard to the EPA for further consideration of whether
it is set at a level requisite to protect the public health while
providing an adequate margin of safety from the risk of shortterm
exposure to PM2.5
The Court also granted the petition for review of the secondary NAAQS for the fine PM brought by the environmental groups. The Court said EPA unreasonably concluded that the NAAQS are adequate to protect the public welfare from adverse effects on visibility.
The Clean Air Scientific Advisory Committee (CASAC),along with medical and public health groups who submitted comments, challenged the EPA’s proposal to retain the existing level of the primary annual fine PM standard at 15 μg/m3 . They urged the EPA to lower the level to somewhere between 12 and 14 μg/m3. The CASAC and several public commenters also objected to setting the secondary standards for fine PM at the same level and averaging time as the primary standards, arguing that they were insufficient to protect against adverse visibility effects.
The Court decided not to vacate the annual standard, but only remand it for Agency review. The Court left open the possibility EPA could provide a better explanation for maintaining the standard at 15 μg/m3. However, based on the strong opposition to the standard and CASAC’s recommendation to lower the standard, EPA will most certainly oblige.
So what is the potential impact of a lower PM 2.5 standard? The yellow and orange dots are areas that have readings below the 15 μg/m3 but within the CASAC recommendations. Of course its not just more potential non-attainment areas, it is also the red dots finding it much hard to reach attainment.
States will need to be aggressively looking at diesel reductions as well as a stronger CAIR program to reach the standards.