When was the first federal attempt to regulate pollutant emissions in the United States enacted?

The first federal attempt to regulate pollutant emissions in the United States was established with the Air Pollution Control Act of 1955. This legislation signified a turning point in environmental policy as it recognized the need for federal involvement in addressing air quality issues, primarily in response to increasing public concern over urban smog and industrial pollution. The 1955 Act aimed to fund research and establish air quality standards, laying the groundwork for more comprehensive air pollution control measures in subsequent years. This foundational law set the stage for later, more stringent regulations, such as the Clean Air Act of 1963, which significantly expanded federal authority in regulating air emissions. Therefore, the correct answer is 1955, as it marks the initial federal initiative to address air pollution from a regulatory standpoint.