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De Minimis for Air Emissions

How a business or government operation may qualify as a de minimis facility.

Any activity or workplace that causes contaminants to be released into the air in Texas requires authorization from the TCEQ. De minimis is one of four choices a small business owner or local government representative may have available to them to satisfy air authorization requirements in Texas. The other three are:

If a small business owner or local government representative determines that an operation or activity meets the requirements of the De Minimis Rule and can show suitable proof that de minimis applies to their location, then no other state air authorization is required.

Tools to Determine if a Facility is De Minimis

List of De Minimis Facilities

Reviewing the De Minimis Facilities or Sources list is the easiest way to determine if an operation qualifies for a de minimis authorization. That list may be obtained at:

The list may also be obtained by calling the TCEQ's Air Permits Division in Austin at 512-239-1250 and asking for the latest list of De Minimis Facilities.

De Minimis Rule

A. Material Use - Paragraph 2 of the rule shows de minimis limits by the amount and type of materials that are allowed to be used in a year's time. View the rule at 30 Texas Administrative Code, Chapter 116

B. Effects Screening Levels (ESL) - Paragraph 3 of the rule shows how a facility meets the De Minimis Rule by evaluating the daily and annual emissions from the site. This chart shows the sitewide emission rate caps based on ESL: 30 TAC Chapter 116.119(a)(3) .

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Record Keeping: It's the Law

Although record keeping is important for any operation, it is especially important for a small business or local government claiming de minimis. The overall requirements for keeping appropriate records and the authorization for TCEQ investigators to examine those records are found in the Texas Health and Safety Code, Subtitle C, Air Quality, Chapter 382: Monitoring Requirements and Examination of Records (Section 382.016)

At a minimum, de minimis record keeping should consist of invoices for amounts of materials purchased. Facility owners and operators should maintain enough information to demonstrate they meet the De Minimis Rule requirements. Remember that these records must be produced upon request.

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In Conclusion

The phrase "de minimis" literally means "of minimum impact." It is intended that qualification for de minimis means there will be no significant contamination of the air. And it is also important to remember that the entire job site must meet de minimis standards in order to qualify under this rule.

Don't forget that de minimis is just one option when it comes to satisfying state air authorization requirements in Texas. Facilities that do not qualify for de minimis may pursue a more appropriate authorization such as Permit by Rule, Standard Permit, or a New Source Review Permit.

Where can I find more information and assistance?

The TCEQ's Small Business and Local Government Assistance Section offers free, confidential help to small businesses and local governments working to comply with state environmental regulations. Call us at (800) 447-2827 or visit our webpage at

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