State and local environmental regulators have published a new report to set the record straight on the nation’s air quality and challenge the talking points of activist groups.

“Through the Clean Air Act’s framework of cooperative federalism, hard-working state and local air agencies have been responsible for tremendous progress in virtually every measure of air quality,” the Association of Air Pollution Control Agencies (AAPCA) said today in the report. But these environmental outcomes have remained “under the radar for most Americans,” according to the report, with some believing air quality is getting worse, not better.

“With media more likely to report bad news combined with often apocalyptic framing by advocates and limited understanding of technical air quality information, it is no wonder that the public is often confused about air quality in their city, county, state, and nation,” AAPCA said in today’s report, titled “The Greatest Story Seldom Told: Profiles and Success Stories in Air Pollution Control.”

“Despite tremendous strides in all measures of air quality since 2000, trends in national and international surveys show that there has been little movement in American public perception about air quality,” the report concludes.

AAPCA represents more than 40 state and local environmental agencies across the country. Under the Clean Air Act, these state and local regulators are largely responsible for meeting air quality standards set by the federal government.

The report may have been timed to preempt claims made by environmental activist groups around Earth Day on April 22. In past years, environmental groups have also used the month of April to publish their own reports on air quality and call for strict new federal emissions limits across the economy. But some environmental regulators have complained that activists are making misleading claims about air quality to push their agenda.

“We’ve made great strides and more work needs to be done,” Will Allison, Colorado’s top air quality regulator, told Energy In Depth in 2015. “But it makes our jobs harder when positive trends are being spun the exact opposite way.” Allison was responding to claims from the American Lung Association (ALA) that Denver’s ozone levels are higher today than they were during the 1970s and the days of city’s infamous “Brown Cloud.”

A columnist with the Denver Post called those claims “brazenly misleading” and argued the ALA should not “misrepresent long-term trends” or “fudge the data” to build political support for it agenda. When challenged, the group retracted its claim, admitting “ozone is not worse than the 1970s.” The following year, after another round of claims from the ALA, state air quality regulators were forced to respond again. “[W]e had a very good year with very low ozone levels,” Allison told The Denver Post, “but even that doesn’t seem to change the way the grades come out of the ALA system.”

The ALA’s “State of the Air” report, usually released around this time of year, has also attracted criticism from environmental regulators in other parts of the country. “We don’t agree with their methodology,” an official with the Maryland Department of Environment told E&E News after the ALA’s 2015 report. “We want people to know … that their air is healthy to breathe,” a spokesman for the Indiana Department of Environmental Management said the same year.

The U.S. Environmental Protection Agency (EPA) has also challenged the claims made in the ALA report. “The EPA has nothing to do with that report,” an agency official based in Kansas told a Missouri newspaper in 2015.

Other environmental groups, such as the Sierra Club, routinely cite the ALA’s findings to support their own campaigns against oil, natural gas and coal production. “Unmitigated climate change is projected to worsen air quality across large regions of the U.S.,” the Sierra Club’s Colorado chapter wrote in January. Based on ALA data, 166 million Americans breath unhealthy air “increasing our risk of an early death or conditions, such as lung cancer, asthma, heart damage and reproductive harm,” the group claims.

But according to the AAPCA report, such rhetoric is not supported by the facts. “Air quality has improved dramatically … and ambient air monitoring data continues to reveal the downward trend of air pollutants,” the report says. “As of 2015, combined emissions of the six criteria air pollutants for which there are national ambient air quality standards were down 71 percent since 1970,” the report concludes.