SES Qualified Source Test Individual and Observer (QSTI /QSTO) Program

The Source Evaluation Society QSTI/QSTO Committee has developed general requirements for applicants for the SES QSTI/QSTO approval. The SES will issue approval documents to qualified applicants in the following methods groups:  

  • Group 1 - Manual Gas Volume and Flow Measurements and Isokinetic Particulate Sampling Methods
  • Group 1a - Stack Gas Flow Rate Measurements Sampling Method
  • Group 2 - Manual Gaseous Pollutants Source Sampling Methods
  • Group 3 - Gaseous Pollutants Source Sampling Methods
  • Group 4 - Hazardous Metals Measurement Methods
  • Group 5 Part 75 CEMS RATA Testing

To apply for initial QSTI or QSTO approval, you must meet the following requirments:  

You should direct applications and associated information for SES QSTI or QSTO approval and any questions about these requirements or for information about the program to the SES QSTI/QSTO Administrator by email to the SES QSTI/QSTO Administrator, Theresa Lowe at

Note also the ECMPS AETB reporting requirements includes a provision for an email address be noted for the exam provider. This address is

  • The SES will maintain confidentiality for all application information and share such information only as necessary with no one but the SES QSTI/QSTO Committee. The SES QSTI/QSTO administrator will review and advise you if you should provide any additional information to complete your application. The Committee meets monthly to review applications, and SES posts the date of the next Committee meeting on the SES website. (Select SES Home page for the date of the next SES QSTI/QSTO application review meeting.) The deadline to submit your application and ensure that the committee acts on it at the committee’s next meeting is three days prior to the date of the scheduled meeting.
  • If you have any questions, please contact Theresa Lowe.
  • Thank you,

    Theresa Lowe
    SES QSTI/QSTO Program Administrator
  • Announcing Online QSTI Exams

  • What is the QSTI/QSTO program?
  • QI versus QSTI - What is the Difference?
  • Methods Covered Under Each Group Exam
  • SES QSTI/QSTO Approval Application and Renewal Policies and Procedures
  • Appeal Process Policy Update and 30-day Waiting Period Update
  • Comprehensive Exam Study Guide
  • Tips for Passing the Exams/Study Guidelines
    • RFT (viewable in any word processor)
    • PDF

    QSTI Program Complaint/Suspension Guidelines

    Frequently Asked Questions

    List of Qualified Stack Testing Individuals/Qualified Stack Testing Observers