In 2022, the Environmental Protection Agency approved the use of virtual reality (VR) for Method 9 smoke school certification under an alternative method designation known as ALT-152. This designation allows approved technologies to be used in place of traditional in-person field certification, provided they meet the same accuracy and performance standards required under EPA Method 9.

What Is ALT-152?

The ALT-152 designation functions as an umbrella — with each separately approved platform receiving its own unique suffix. CAA's VirtualOpacity® platform, approved in 2024, carries the designation ALT-152A. Not all VR smoke school providers use a separate suffix, meaning platforms operating under the original ALT-152 designation may represent distinct implementations with independent development and approval histories.

CAA was the first vendor to bring a commercial virtual smoke school product to market. For full documentation, reference the official EPA ALT-152A approval letter.

Why ALT-152A Exists

Traditional smoke school certification requires in-person field testing, which presents recurring logistical challenges — travel, scheduling constraints, weather variability, and resource demands. ALT-152A was developed to address these limitations by allowing approved virtual platforms to replicate the training and evaluation process in a controlled, repeatable environment.

Despite common misconceptions, ALT-152A is not simply "using VR" in a general sense. It is a formal EPA-approved alternative method. Any platform operating under this designation must meet strict criteria for accuracy, repeatability, and regulatory defensibility. Observers must still demonstrate the ability to accurately determine opacity in accordance with Method 9 standards.

Benefits of Virtual Smoke School

Virtual smoke school platforms approved under ALT-152 offer several practical advantages over traditional field certification:

  • Flexibility: Certification can be completed without travel or fixed scheduling requirements.
  • Consistency: Controlled scenarios eliminate variability caused by weather or ambient lighting conditions.
  • Accessibility: Easier coordination for organizations managing certification across multiple observers or locations.
  • Reduced Downtime: Less time away from job sites or operational responsibilities.

Additional advantages specific to CAA's platform are available on our VR client information pages.

How Virtual Smoke School Fits Into EPA Method 9 Certification

Virtual smoke school replaces the field certification component of Method 9 when conducted under an approved alternative method like ALT-152A. It is typically paired with a lecture component — such as a self-paced visible emissions observation lecture — which provides the foundational knowledge required for accurate opacity readings. Together, these two components ensure that observers are prepared to perform defensible, regulation-compliant opacity determinations.

Is Virtual Certification as Effective as In-Person Smoke School?

This is one of the most common questions surrounding ALT-152A. To earn EPA approval, an alternative method must demonstrate accuracy equivalent to the standards documented in the EPA's foundational collaborative study: Evaluation and Collaborative Study of Method for Visual Determination of Opacity of Emissions from Stationary Sources, EPA-650/4-75-009, January 1975.

When CAA submitted VirtualOpacity® for review, the platform's observer accuracy results surpassed those documented in that EPA study. It is worth noting, however, that no widely established independent dataset currently confirms broad superiority of virtual methods over in-person smoke schools. The EPA documentation linked above includes the evaluation criteria and supporting data used to determine that VirtualOpacity® meets regulatory requirements.

State-by-State Adoption

While ALT-152 and ALT-152A are approved at the federal level, implementation varies by state. Some states have formally accepted virtual certification under these alternative methods; others are still evaluating or have not yet issued guidance.

CAA maintains current information on state acceptance and continues to work with regulatory agencies to expand approvals. Learn more about the status of ALT-152A acceptance by state. Because this landscape is actively evolving, confirm acceptance with the relevant state agency before scheduling certification.

Key Takeaways

ALT-152 represents a significant shift in how Method 9 certification can be delivered, introducing virtual reality as an EPA-approved alternative to traditional field testing. CAA's VirtualOpacity® platform, approved under ALT-152A, provides a broadly applicable option for certification that maintains regulatory integrity while improving accessibility. As adoption continues at the state level, virtual smoke school is likely to become an increasingly common pathway for Method 9 certification, particularly for organizations seeking flexibility without compromising compliance.

Questions or Next Steps?

If you have questions about ALT-152A, state acceptance, or how virtual smoke school fits into your organization's certification process, contact Compliance Assurance Associates, Inc. at info@compliance-assurance.com or 901-381-9960.