How to Determine Black Smoke Opacity At Smoke School

Reading black smoke accurately takes more than simply deciding whether a plume looks light or dark. During a smoke school test, the observer must estimate how much of the background is obscured by the plume and assign an opacity value in 5% increments.

Our short instructional video, “How to Determine the Opacity of Black Smoke on a Smoke School Test,” demonstrates a practical method for evaluating black smoke and developing more consistent opacity estimates.

Watch: How to Assess Black Smoke Opacity

The 3-minute video focuses specifically on evaluating black smoke during smoke school training.

Watch “How to Determine the Opacity of Black Smoke on a Smoke School Test” on YouTube

The video explains several concepts that can help when preparing for an EPA Method 9 visual test, including:

• Understanding what opacity is.
• Selecting the appropriate portion of the plume for your observation.
• Estimating black smoke opacity using the 5% increments used during smoke school testing.
• Becoming familiar with the appearance of common black smoke opacity levels.
• Narrowing a plume to a likely opacity range before choosing a final value.

Building Black Smoke Observation Skills

Repeated exposure to known opacity values is an important part of developing visual estimation skills. As you become more familiar with what different levels of black smoke look like, it becomes easier to distinguish between nearby values during a test.

These observation techniques are applicable to both traditional in-person smoke school and virtual smoke school. Although the training environment may be different, the objective is the same: accurately estimate the opacity of a visible emission.

Virtual training also provides an opportunity to repeatedly practice with standardized smoke plumes. An EPA Study evaluating observer performance found that participants trained using VR Smoke School produced more accurate opacity observations than participants trained using traditional in-person smoke school.

If you are preparing for EPA Method 9 certification, learn more about our online EPA Method 9 certification process and register for a free account. After registration, you can immediately practice assessing black smoke plumes through our online program at no cost. No credit card or purchase necessary.