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 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 an 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.
