New to Smoke School?

The following information will help you understand what it is and who may need it.

What are Visible Emissions?

Power Plant Emissions

A visible emission is the visible particulate matter that occurs as the result of a process. Smoke exiting a stack at a power plant is a visible emission

Road Emissions

Dust produced from driving down a gravel road is a visible emission

House Emissions

Smoke from the chimney of your fireplace is a visible emission

What is Opacity?

When you’re talking about visible emissions, opacity is the degree to which light is blocked by the emissions. When you are observing emissions there is always a background behind the smoke plume. This background can be anything, but ideally it should contrast with the emissions you are observing.

Opacity with Trees as Background Tree as a background
Opacity with Sky as Background Sky as a background
Opacity with Bricks as Background Building as a background

What is Smoke School?

Smoke school is the process of being trained and certified to observe the opacity of visible emissions. There are two components to smoke school; lecture and field certification.



Recommended every 3 years. Covers observation and documentation procedures for making visible emissions observations.


Field Test

Field Test

Required every 6 months. Trains and tests you on your ability to read the opacity of visible emissions.

Alternative Names for Smoke School

Smoke school is a generic term for the entire training/certification process.
Smoke school may also be called:

EPA Method 9 Certification
Opacity Certification
Opacity Training
Visible Emissions Training
VEO Training

Who Attends Smoke School?

Industrial & Commercial Sources +

Many industrial & commercial sources that have the potential to emit particulate matter into the air are regulated by Federal, State or municipal opacity standards. A facility is compliant with these standards when the opacity of their emissions is under the limit. In order to demonstrate compliance, in-house personnel attend smoke school to become certified to perform the opacity observations.

industrial & commercial sources industrial & commercial sources

Many commercial sources have opacity limits; from large power plants to small quarry operations.

Environmental Consultants +
Environmental Consultants

As an alternative to in-house personnel making the opacity observations, some facilities hire third-party consultants to perform their emissions observations. These consultants maintain their ability to perform these observations by attending smoke school.

Regulatory Inspectors & Enforcement Agents +
Regulatory Inspectors & Enforcement Agents

Inspectors from federal, state or municipal regulatory agencies also attend smoke school. These inspectors are responsible for ensuring opacity limitations are not exceeded by sources of visible emissions.

Community Watch Groups +
Community Watch Groups

In areas where a facility is a repeat violator of their opacity limits, community watch groups will randomly perform opacity observations to ensure the facility is compliant and the air pollution in their community is kept to a minimum.


The Certification Process

Lecture Screenshot
Step 1:Review Online Lecture Program

Our online lecture program will cover everything you need to know about observing visible emissions and properly documenting your readings. Info about our lecture program can be found here

Attend a Smoke School Field Event
Step 2: Register for a Smoke School Field Event.

AeroMet has an extensive schedule of public smoke schools throughout the U.S. Public smoke schools are open to anyone and are held every 6 months to ensure your certification doesn’t expire. Our full schedule can be found here

Attend a Smoke School Field Event
Step 3: Attend a Smoke School Field Event.

During the field event, our instructors will demonstrate various levels of opacity using a custom smoke generator. After your eyes have been calibrated, they will run practice tests until everyone is ready to take the certification test. AeroMet will run certification tests until everyone passes.

Step 4:Re-Certification

To maintain your certification, you must pass the field certification test every 6 months. This is why we return to each field event location every 6 months.

View Smoke School Schedule & Get Registered