Last week, the Clean Air Scientific Advisory Committee formally transmitted its recommendations to EPA Administrator Regan regarding the PM2.5 NAAQS.  Consistent with trade press reporting over the past few months, the majority of CASAC members recommended that the PM2.5 NAAQS be set between 8-10 ug/m3.  A minority recommended the range be set between 10-11 ug/m3.  I’d be surprised if the revised NAAQS is set above 10 ug/3

For me, what’s interesting about the letter is the suggestion that:

EPA should consider the implications of the exceptional events approach when applied to wildfires, particularly with respect to the risk assessment.

Apparently, that language was toned from draft language that more strongly suggested that EPA should change its exceptional events policy.  Even so, it’s a pretty important issue.  As the detailed CASAC comments note:

Exceptional events. EPA allows exclusion of wildfire PM events under the exceptional event rule when calculating PM2.5 design values. In some parts of the country wildfires are no longer “exceptional”. The dramatic increase in wildfires over the last decade is not natural; it is a combination of anthropogenic climate change, forest management practices, and power line ignition incidents. These are (in theory) at least partially controllable. Given the potential for significant adverse health events, it may be time to reconsider the current approach to excluding the high PM exposures from wildfire events in design values.

Should we really consider forest fires to be natural events?  After all, Democrats think that the increase in wildfires is tied to human-caused climate change.  Republicans blame Democratic forest management.  Both explanations support the conclusion that many wildfires are not natural events.

At CASAC’s suggestion, I’ve considered the implications of the exceptional events approach and I think it’s time for a change.

The post PM2.5 Emissions From Wildfires — No Longer So Exceptional! first appeared on Law and the Environment.