The California Air Resources Board (CARB) has long been at the forefront of developing and implementing programs aimed at significantly reducing emissions from mobile sources. These mobile sources are the largest contributors to both criteria pollutants and greenhouse gases (GHG) within California. They account for approximately 80% of ozone precursor emissions and around 50% of the state’s total GHG emissions when considering transportation fuel production and distribution. Of particular concern in California are the National Ambient Air Quality Standards (NAAQS) for ozone and fine particulate matter (PM2.5). California experiences some of the most severe air pollution in the United States. Notably, the South Coast and San Joaquin Valley air basins are uniquely classified as ‘Extreme’ nonattainment areas for the federal ozone standard of 70 parts per billion (ppb), the most critical category. These regions also grapple with alarmingly high levels of PM2.5 pollution.
The regulations encompassed within the Advanced Clean Cars II program are a crucial component of California’s comprehensive strategy to address these urgent public health issues, while adhering to both state and federal legal requirements. Emissions originating from motor vehicle engines have detrimental effects on public health, welfare, the environment, and the climate, impacting these areas in numerous interconnected ways. Efforts to reduce one type of emission often contribute to the reduction of others, thereby lessening the overall severity of their combined impacts. Crucially, as the climate continues to warm, controlling ozone pollution becomes increasingly challenging, and the risk of particulate matter release from wildfires escalates. Reducing emissions that drive climate change is therefore essential. This reduction will amplify the effectiveness of efforts to control ozone by targeting the primary pollutants responsible, namely nitrogen oxides (NOx) and hydrocarbons (HC) from fuel combustion. These vital emission reductions are key to stabilizing the climate, mitigating the risk of severe droughts and wildfires, and consequently reducing the associated fine particulate matter pollution.
