Estimating the Impact of Air Pollution Controls on Ambient Concentrations

Abstract

This work describes the development and application of a statistical model that links electricity generating unit (EGU) and mobile source emissions with a city center monitoring cite. The model uses estimated emissions and measured concentrations over the period 2000–2012 in Atlanta, GA, USA to develop counterfactual time series of daily ozone concentrations. Further, the model estimates the sensitivity of observed ozone to each emissions sector. Results show that emissions control policies have had little effect on annual median ozone, have decreased 90th percentile ozone, and have increased 10th percentile ozone. Sensitivities to EGU and mobile emissions are compared and agree well with similar sensitivities calculated using a first-principles chemical transport model.

Question and Answer

Questioner: Dr. Amir Hakami

Question: Does the error associated with the detrended values overlap the observations?

Answer: The error associated with the daily estimates of the detrended concentrations tends to be small compared to the change from the observed value. For ozone, for instance, the mean absolute daily contribution of meteorology is 8.4 ppb. The 95 % confidence interval on the mean absolute contribution is less than 3 ppb. The process of variable selection in the detrending model eliminates those covariates that might add significant error to the detrended values.