Evaluating the Effectiveness of Voluntary Programs: Did Ohio's Tox-Minus Initiative Affect Participants' TRI Emissions?

In this paper we evaluate whether Ohio’s Tox-Minus Initiative had a discernible effect on participants’ emission reductions relative to non-participants. We expect this to be the case if there are private benefits of program participation that outweigh its costs. To investigate whether the Tox-Minus Initiative resulted in greater reductions in TRI-reported air emissions from the top 100 emitters, we use a triple difference approach to compare emissions before and after the program. This is done using both the simple difference in emissions between 2003 and 2012 and a fixed-effects, panel regression. To form an appropriate comparison for participants, we use propensity score matching estimation techniques based on pre-participation attributes. Our results suggest that being invited to the program, regardless of whether a facility joined the Tox-Minus Initiative, produced a significant decline in the absolute level of air emissions. Degree of regulatory attention also appears important, though we find that participants reduced emissions subject to the Clean Air Act by significantly more than non-participants in the post policy period.