In recent years, the United States has faced rising concerns regarding climate change. Communities across the country have noted an increase in wildfires, heat waves and powerful hurricanes. These challenges have spurred debate among legislators, scientists and community members about how to maintain human livelihood while addressing issues such as biodiversity loss and pollution.

Origins of environmental policy in the United States

Environmental science in government policy has roots dating back to the mid-20th century. Americans began to have conversations about protecting the environment in the ’60s. Concerns about pollution, major oil spills and the Cuyahoga River’s spontaneous combustion heightened public awareness.

The Air Pollution Control Act of 1955 was the first national legislation concerning air pollution which aimed to “provide research and technical assistance relating to air pollution control.”

However, that 1955 legislation dealt only with monitoring and research. The first legislation concerning the control and regulation of air pollution did not come until the Clean Air Act of 1963, which led to the establishment of a federal program in conjunction with the U.S. Public Health Service. The 1967 Air Quality Act later placed primary responsibility for air pollution problems on state and local governments, though “the federal government could step in if the state failed to adequately act on its own.”

The U.S. Environmental Protection Agency was established in December 1970, following congressional approval of a reorganization plan proposed by former President Richard Nixon. Reorganization Plan No. 3 of 1970 not only contained guidelines for the establishment of the EPA but also the National Oceanic and Atmospheric Administration. This allowed for a more coordinated and effective response to environmental issues than previous initiatives.

One significant piece of legislation was the Clean Air Act of 1970, later amended in 1977 and 1990, which regulates air emissions from stationary and mobile sources. The act establishes a national right to safe air, preventing polluting industries from simply relocating to more rural areas.

Some of the earliest research conducted by the EPA involved studying photochemical reactions of emitted chemicals, which led to further research on the correlation between ozone concentration and health effects. Over the following decades, research confirmed a clear link between ozone levels and adverse health outcomes.

Particulate matter, or soot, was also studied — generated from vehicles, industry, wildfires and “other combustion-related sources.” This led the EPA to issue the first air quality standards for fine particulate matter, known as PM2.5, in 1997.

In response to evolving air quality standards, EPA researchers implemented Federal Reference Methods and Federal Equivalent Methods to measure air quality more accurately.

Plans and enforcement

The federal government sets national air quality standards, but state and tribal governments must enact and enforce those standards themselves. Each state can set stricter standards for emission sources than those required at the federal level.

One goal of the EPA was to set and achieve National Ambient Air Quality Standards for six principal criteria air pollutants: nitrogen oxides, sulfur oxides, particulate matter, carbon monoxide, ozone and lead. This could be achieved through state implementation plans by enforcing pollutant standards within each state.

A typical state implementation plan generally contains three main components: state-adopted control measures such as statutes and regulations; “non-regulatory” components or additional provisions required by the EPA; and plans for maintenance and enforcement. The EPA collaborates closely with state and local agencies throughout the development of these plans. Once a state implementation plan, or a portion of it, receives EPA approval, its control measures become federally enforceable.

If a state agency fails to submit an acceptable plan — or if the EPA disapproves the submission — the agency is required to establish a Federal Implementation Plan to ensure compliance with national air quality standards.

Current issues and actions

While significant improvements in air quality followed the Clean Air Act and its amendments, environmental challenges persist. In the late ’90s, transitions in climate cycles — coupled with ongoing changes in temperature, drought and snowmelt — likely contributed to conditions fueling more frequent and intense wildfires across parts of the United States.

Wildfire smoke is now one of the largest and fastest-growing sources of air pollution in the country, serving as the leading source of particulate pollution (PM2.5) in the western United States. It accounts for roughly 50–75% of annual PM2.5 emission and contains the same pollutants regulated under the Clean Air Act.

In 2007, the Supreme Court’s ruling in Massachusetts v. EPA determined that greenhouse gases are regulated under the Clean Air Act, giving the EPA authority to regulate emissions of carbon dioxide and other greenhouse gases. This decision significantly expanded the agency’s authority beyond traditional air pollution to include climate change mitigation.

Following the decision, the EPA introduced several initiatives, including the Clean Power Plan, which established a national carbon dioxide emissions performance rate for power plants.

While fossil fuels will continue to be an important source for the nation’s energy, the Clean Power Plan ensures that power plants operate in a more efficient and climate-friendly manner.

The history of environmental policy in the United States highlights the intersection between science and legislation and their combined ability to confront complex environmental issues. Despite ongoing challenges, the foundational decades of research and policy enactment provide hope for a sustainable future.