The first emission standards for automobiles primarily addressed the emission of which substance?

The first emission standards for automobiles primarily focused on hydrocarbons, which are organic compounds made up of hydrogen and carbon. These standards were introduced in response to growing concerns about air pollution and the health impacts associated with vehicle emissions. Hydrocarbons are generated during the combustion process in engines and can contribute to the formation of ground-level ozone and smog, which can have detrimental effects on respiratory health.

By establishing limits on hydrocarbon emissions, regulatory bodies aimed to reduce the overall impact of vehicle emissions on air quality and public health. This initial focus set the stage for subsequent regulations that addressed other pollutants, including nitrogen oxides and carbon monoxide, as the understanding of air quality issues evolved over time. Addressing hydrocarbons was a foundational step in regulating automotive emissions and improving air quality.