On December 15, 2014, the WDNR Air Management Program finalized an update to the PM2.5 background concentration used in dispersion modeling. These values were updated due to the recent designation of the entire state as attaining the PM2.5 standard. The WDNR Guidance on this subject is now available here.

The table below shows the final Wisconsin background concentrations with the previous PM2.5 concentrations crossed out. The final concentrations include a small change from the draft concentrations (as discussed in the September eNews dated September 29, 2014 on this subject): a decrease in the lowvalue of the annual PM2.5 background concentration from 7.6 µg/m³ to 7.3 µg/m³

updated WI concentration for modeling

For questions about the recently published background concentrations or regarding dispersion modeling in Wisconsin, please contact Jon Frost at 651-275-9900 or jfrost@trinityconsultants.com.