What Are Visible Emissions Observations?

Excerpt from Online Visible Emissions Course

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What are visible emissions observations

What Are Visible Emissions Observations?

The term visible emissions observations (VEO) includes several methods that are defined by the EPA, including Method 9, Method 22, and more.

Methods and Definitions

EPA Method 9 visible emission observations are taken of visible emissions from emission sources to quantify opacity of the emissions. Method 9 readings must be taken on a periodic basis by qualified observers - individuals that have been trained and qualified in accordance with Method 9. Method 9 qualification testing occurs at a hands-on, in-person event called a smoke school. Smoke schools must use equipment and procedures that meet Method 9 requirements to document the statistical accuracy and reliability of the observer.

Visible emissions observations have two subsets: Opacity methods (i.e., Method 9) and non-opacity methods (i.e., Method 22 or a permit condition requiring an observation without specifying a method). If your organization's permit requires an opacity observation or opacity reading, Method 9 is implied.

Visible emissions observations include:

  • Method 9 - which quantifies the opacity level.
  • Method 22 - documents the duration of emissions during a specified observation time.
  • Quick Check - a momentary glance without specific criteria or requirement.

A well-trained and certified Method 9 observer should know:
  • The terms, underlying concepts, and principles related to visible emissions observations.
  • A brief history of the evolution of VEO that illustrates the importance of compliance.
  • What steps need to be taken before performing an opacity reading.
  • How to read the opacity of emissions and perform specialized readings. Opacity readers need to understand and avoid interferences that may bias or invalidate observations.
  • How to complete the VEO form.

This course covers the above points and prepares you for field qualification testing.

NOTE: Throughout the course, links that are bold red will take you to our glossary page for a definition of the selected text.