Revised On: Dec. 28, 2023 - 5:00 p.m.
Most used oil in Arizona is burned as a substitute fuel for energy recovery. Because it has been used, used oil may contain many more contaminants than virgin oil. Because it may contain more contaminants in higher concentrations than virgin oil, there is a potential that more contaminants could be released into the atmosphere from burning used oil, than from burning a virgin oil or other cleaner-burning fuel.
The EPA has determined that only certain contaminants pose significant threat to public health or the environment. As a result, the EPA has established limits for the maximum concentrations for the contaminants of concern. These limits were set so that the emissions from burning used oil containing these contaminants, at or below these limits, will pose no more threat to public health or the environment than the emissions from burning a cleaner-burning fuel, such as virgin oil or diesel.
The maximum contaminant concentrations, including a 100 degree or more limit on the minimum flashpoint (a safety consideration) that a used oil fuel may have, are referred to as the used oil specifications. Following are used oil specifications (other than flashpoint, which is 100 degrees or more):
| Contaminant |
Maximum Concerntration
(In Parts Per Million) |
| Arsenic* |
5 or less |
| Cadmium* |
2 or less |
| Chromium* |
10 or less |
| Lead* |
100 or less |
| Polychlorinated biphenyl (PCBs) |
Less than 2 |
| Total Halogens** |
1,000 or less* |
* This specification is for Total Metals, not Total Characteristic Leaching Procedure (TCLP).
** Only for total halogen concentrations 1,000 parts per million (ppm) or more for which the presumption of mixing has been successfully rebutted. |
Used oil that does not meet all the specifications is referred to as off-specification used oil, except when either of the following two conditions apply:
- PCBs are 50 ppm or more. This used oil is regulated as a toxic waste under the Toxic Substance Control Act (TSCA).1
- Total Halogens exceed 1,000 ppm. This used oil may be regulated as a hazardous waste.2
In Arizona, an air quality permit is required any time burning is to take place in a commercial or industrial application. Among other things, the air quality permit will specify which fuels may be burned and the maximum contaminant emissions allowed. Permits which allow burning used oil typically specify the cleaner-burning on-specification used oil. If a facility were to elect to burn off-specification used oil, it would have to demonstrate that it is capable of cleaning up the resulting emissions to meet applicable air quality standards.
Learn more about air quality permits in Arizona | Learn More >
140 CFR 761
2Under 40 CFR, Parts 260 through 266, 268, 270 and 124
