Smoke School History

The PCV Valve was added to all new automobiles as part of a CAFÉ standard in 1960, and several additional federal bills regarding air pollution were passed in the 1960s, funding studies and defining jurisdictions.

The first Clean Air Act (CAA) was passed in 1963. It focused on creating research methods for monitoring and controlling air pollution from stationary sources — the first modern environmental law. The primary goal was to protect and enhance air quality to promote public health. It provided $95 million in funding to assist state and local governments in pollution prevention.

The 1967 Federal Air Quality Act required states to establish air quality regions and adopt Ambient Air Quality standards, serving as a model for State Implementation Plans (SIPs). The law also transferred control of automobile emissions to the federal level.

The U.S. government published AP-30 — "Optical Properties and Visual Effects of Smoke-Stack Plumes" — a result of a joint study between industry and government on the study of opacity. The document detailed the accuracy of a human smoke reader compared to a transmissionmeter and stated the effect of readings when the sun is not in the correct position relative to the emission source. AP-30 established opacity as a federal regulatory tool.

The EPA was formed in December 1970. The EPA is an independent executive agency of the government whose mission is to protect human health and the environment. The EPA has several functions including research, grants, and education. For the VEO industry, the main function of the EPA is to develop and enforce clean air regulations.

The CAA was updated shortly after the formation of the EPA. The 1970 CAA amendments signified a major change to air quality regulations, elevating the federal government's role and authority in clean air regulation. The legislation called for development of federal and state air quality emissions standards for stationary and mobile sources, with the EPA having authority to base regulations on science, not political expediency.

For stationary sources, the CAA created four regulatory programs:

• National Ambient Air Quality Standards (NAAQS) — referred to as "knacks"
• State Implementation Plans (SIPs)
• New Source Performance Standards (NSPS)
• National Emission Standards for Hazardous Air Pollutants (NESHAPs)

In the 1970s, Prevention of Significant Deterioration (PSD) permitting and new source review requirements were also instituted.

SIPs were submitted to the federal government in the early 1970s, approved by the EPA, and entered into the Code of Federal Regulations (CFR).

On November 12, 1974, the EPA published "Method 9 — Visual Determination of Opacity from Stationary Sources" in the Federal Register. It was immediately challenged by a cement plant in Portland that was directed to maintain a 10% opacity limit for emissions. The Portland Cement Association sued the EPA on grounds that Method 9 was not accurate enough to support the standard.

As a result of the Portland case, the EPA spent a year conducting field studies on Method 9. The following changes resulted:

• The opacity limit for Portland cement plants was raised from 10% to 20% opacity.
• The Method 9 data reduction scheme was revised to include averaging.
• More specific observation and training requirements were established.

The resulting Method 9 was the first modern version of the method. Since the second promulgation, there has been only one minor change to Method 9.

With the inception of Method 9, the EPA stopped using the Ringelmann numbers as a reference for opacity measurements.