On a clear day, you can’t actually see forever — if you follow the blue sky out to the horizon, you will often see it become somewhat more pale and opaque, owing to ‘visible pollution,’ or “haze” — the result of the interaction of sunlight with particulate matter in the air.

Before the modern industrial age, haze was largely attributed to wind-blown dust, soot from wild-fires, and other types of volatile organic compounds (VOC) released by trees and plants into the atmosphere from America’s vast forest lands.

For at least the last half-century, however, industrial burning of coal for oil refining, generating electricity, and steel manufacturing, has released sulfur dioxide into the air, resulting in sulfuric acid being the predominant component of modern-day haze. In addition to reducing visibility, this haze has been found to irritate the eyes and throat, causing everything from asthmatic reactions to bronchitis-like symptoms.

It has become enough of an issue that, pursuant to the mandate of the Clean Air Act (CAA), the EPA began monitoring the causes and presence of haze over national parks in earnest in 1989, enacting the Regional Haze Rule. The Regional Haze Rule requires local and government agencies to work together to reduce haze in the US’ 150+ national parks by developing and implementing air quality protection regional haze plans (RHP), which are then submitted to the EPA for approval within six to 12 months. The reporting deadlines for RHPs began in 2007, with the next deadline of 2021, 2028, and then to be submitted every 10 years.

A half dozen ‘red’ and ‘blue’ states submitted their RHPs ahead of the July 31, 2021, deadline, e.g., Kansas, Massachusetts, Michigan, New York, Ohio, Texas and Wisconsin.

By November 2023, when roughly two thirds of the states had submitted their RHP’s with no response, environmental groups filed suit against the EPA on their behalf, seeking to compel review and/or approval of the RHP’s as directed in the Regional Haze Rule.

Now, after more than a year of litigation and negotiation, the EPA has, in the last 10 days, signed a consent decree with the states, committing to address the RHPs of Ohio, Texas, Arkansas and Oklahoma, between Aug. 30, 2024, and Dec. 31, 2025. Industry insiders suggest this another recent example of increasing public interest in environmental protection coalescing into political pressure and action.