The value relevance of nonfinancial measures of air pollution in the electric utility industry

This study examines the relation between the market value of equity and nonfinancial pollution measures (sulfur dioxide emissions) that capture firms' exposure to future environmental liabilities. I find that a nonfinancial pollution proxy is value-relevant for high-polluting electric utilities targeted for air pollution abatement by Phase One of the 1990 Clean Air Act Amendments (CAAA). On average, these utilities' exposure to (unbooked) future environmental liabilities decreased their mean 1990 share price by 16 percent. Moreover, the value relevance of the nonfinancial pollution proxy (1) increased in response to the passage of the stringent 1990 CAAA environmental legislation, and then (2) declined as the market subsequently reduced estimated compliance costs in response to changing economic and technological factors. Utilities not targeted by Phase One of the 1990 CAAA faced minimal exposure to future environmental liabilities and I find no significant relation between their pollution indicators and share prices. I also find that investors in the high-polluting rate-regulated utilities that were targeted by Phase One positively value a favorable regulatory climate.