Carbon pricing, co-pollutants, and climate policy: Evidence from California

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Carbon pricing policies, a critical instrument to manage the costs of greenhouse gas (GHG) pollution, now cover roughly 20% of the world’s carbon emissions from fossil fuel combustion. By increasing the price of fossil fuels via a carbon tax or a cap-and-permit system, these policies reduce their use and provide incentives for investments in alternative energy sources and energy efficiency. Carbon pricing can also yield public health co-benefits by reducing emissions of hazardous air co-pollutants along with carbon dioxide and can, in principle, improve environmental equity by reducing disproportionate pollution burdens in socioeconomically disadvantaged communities. In this issue of PLOS Medicine, Rachel Morello-Frosch and colleagues report the first evidence-based assessment of air pollution equity outcomes of California’s carbon pricing policy implemented in 2013. They found that, over the 2011–2015 study period, emissions from industrial facilities of GHGs and co-pollutants—particulate matter (PM2.5), sulfur oxides, nitrogen oxides, volatile organic compounds (VOCs), and air toxics (roughly 600 chemicals subject to Toxics Release Inventory reporting)—were almost as likely to increase as to decrease and that neighborhoods with emission increases tended to have higher percentages of racial and ethnic minority, poor, less educated, and linguistically isolated residents. These findings suggest that climate policy can best fulfill its potential if designed explicitly to achieve widely shared health co-benefits and improved environmental equity.