EPA’s final methylene chloride rule allows continued use only for a narrow set of uses under the Workplace Chemical Protection Program (WCPP). For those allowed uses, EPA set an 8-hour exposure limit of 2 ppm and a 15-minute exposure limit of 16 ppm. EPA also uses a 1 ppm action level for the 8-hour result to determine how often employers must continue monitoring. In practice, the higher the measured exposure, the more frequent the required monitoring.
Who can still use methylene chloride?
Under EPA’s final rule, continued use is limited to these categories: production of other chemicals, production of battery separators for electric vehicles, use as a processing aid in a closed system, use as a laboratory chemical, use in plastic and rubber manufacturing, use in solvent welding, and certain specified federal uses subject to strict workplace controls. EPA says these are the uses that continue under the WCPP while consumer uses and most industrial and commercial uses are prohibited.
What exposure limits apply?
EPA’s WCPP sets two key workplace limits for methylene chloride:
- ECEL: 2 ppm as an 8-hour time-weighted average
- EPA STEL: 16 ppm as a 15-minute time-weighted average
EPA also uses an ECEL action level of 1 ppm as the trigger for certain compliance activities, including periodic monitoring.
How often is monitoring required?
EPA ties monitoring frequency to the concentration measured. The main schedule in EPA’s compliance guide is:
| Measured exposure | Monitoring required |
|---|---|
| < 1 ppm (8-hour TWA) and ≤ 16 ppm (15-minute TWA) | ECEL and STEL monitoring at least once every 5 years |
| < 1 ppm (8-hour TWA) and > 16 ppm (15-minute TWA) | ECEL monitoring at least once every 5 years and STEL monitoring every 3 months |
| 1 to 2 ppm (8-hour TWA) and ≤ 16 ppm (15-minute TWA) | ECEL monitoring every 6 months |
| 1 to 2 ppm (8-hour TWA) and > 16 ppm (15-minute TWA) | ECEL monitoring every 6 months and STEL monitoring every 3 months |
| > 2 ppm (8-hour TWA), regardless of 15-minute result | ECEL monitoring every 3 months and STEL monitoring every 3 months |
This means a workplace that is exactly at 2 ppm is not over the 8-hour limit, but it still remains in the range requiring ECEL monitoring every 6 months if the 15-minute result is at or below 16 ppm.
Key compliance dates for most existing non-federal workplaces
EPA’s compliance guide highlights these dates for most users continuing under the WCPP:
- May 5, 2025 — initial monitoring
- August 1, 2025 — exposure limits and dermal protections
- October 30, 2025 — exposure control plan
EPA’s main methylene chloride page also says that, for continuing uses under the WCPP, most workplaces have 18 months after finalization of the rule to comply with the program.
Bottom line
EPA’s final methylene chloride rule is not a broad exemption for industrial users. It allows only a limited group of continuing uses, and those users must stay within EPA’s workplace exposure limits and follow the required monitoring schedule based on measured concentrations. For many employers, the real compliance question is not just whether they can still use methylene chloride, but whether their measured exposures place them on a 5-year, 6-month, or 3-month monitoring cycle.