Santiago Megacities Partnership: Assessment of Air Quality Management in the Santiago Metropolitan Region

This report presents results from a comprehensive assessment of the benefits and costs of air quality management in the Santiago Metropolitan Region over the past three decades. During this time period, regulatory actions led to significant improvements in the region’s air quality. While these improvements are well documented, the benefits and costs of the regulatory action remain poorly understood. Currently, benefit-cost analyses of environmental regulations are done prospectively, or prior to implementation of regulations. No analysis has systematically assessed the realized benefits and costs of the
universe of environmental regulations impacting air quality in the region. Authors aim to address this gap by designing and conducting a benefit-cost analysis spanning the years 1990 through 2020.

Additionally, within this retrospective benefit-cost analysis, authors conduct a quantitative assessment of the effectiveness of MMA’s critical episode management system, which restricts certain polluting activities in the region in anticipation of air quality ‘episodes’, or days with very poor air quality during winter. Authors assess monitored air quality, modeled air quality, and meteorological data available to the MMA team, in a retrospective manner, to understand which set of these variables best predict an air quality episode, and also calculate economic benefits and costs associated with an episode declaration. In this case, we define episode declaration as days where mitigation measures were put into place to decrease PM2.5 concentrations when they are forecasted to be above a certain threshold concentration.