The Road to Zero Emissions
CARB has been a leader in developing programs designed to reduce emissions from mobile sources. Mobile sources are the greatest contributor to emissions of criteria pollutants and greenhouse gases (GHG) in California, accounting for about 80- percent of ozone precursor emissions and approximately 50-percent of statewide GHG emissions, when accounting for transportation fuel production and delivery. The National Ambient Air Quality Standards (NAAQS) for two of these criteria pollutants—ozone (sometimes referred to as smog) and fine particulate matter (PM2.5, sometimes referred to as soot)—are particularly relevant in California. California suffers some of the worst air pollution in the nation. The South Coast and San Joaquin Valley air basins are the only two regions in the country classified as ‘Extreme’—the worst category—for nonattainment of the federal ozone standard of 70 parts per billion (ppb). These areas also suffer some of the worst levels of PM2.5 pollution. The suite of regulations within Advanced Clean Cars II are an integral part of California’s strategy to address these pressing public health needs, in compliance with state and federal law. Emissions from motor vehicle engines hurt public health, welfare, the environment, and the climate in multiple interrelated ways. Reducing emissions of one kind supports reducing emissions of others and contributes to decreasing the severity of their impacts. In particular, as the climate warms, ozone becomes harder to control and more particulate matter is released from wildfires. Reducing the emissions that cause climate change will lead to greater reductions in ozone from the efforts to reduce the pollutants that cause it, which are primarily oxides of nitrogen (NOx) and hydrocarbons (HC) from fuel combustion. These emission reductions will help stabilize the climate and reduce the risk of severe drought and wildfire and its consequent fine particulate matter pollution.