Criteria air pollutants are those that are deemed by the administrator of the EPA to be widespread and to "cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare...." EPA data shows that levels of the various criteria air pollutants have declined 29% to 94% since the 1980s. Likewise, combined emissions of hazardous air pollutants have declined by about 58% since the 1990s. Hazardous air pollutants are those that "present, or may present, through inhalation or other routes of exposure, a threat of adverse human health effects ... or adverse environmental effects...." A scientific, nationally representative survey commissioned in 2019 by Just Facts found that 40% of voters falsely believe the air in the United States is now more polluted than it was in the 1980s.