Background
On September 28, 2023 the South Coast Air Quality Management District (SCAQMD) proposed its latest amendments to existing regulations that govern air emissions from medical sterilization and other related operations. SCAQMD further clarified these proposed rules in a working group meeting on October 4, 2023. The proposed rule differs in many ways from the EPAs recently proposed NESHAP that regulates these same sources. The SCAQMD rule is proposing even lower emission limits compared to the NESHAP as well as additional monitoring requirements including fenceline and mobile monitoring.
Rule Summary
The proposed amendments to Rule 1405 reduce emissions of ethylene oxide to the lowest level of any regulations for commercial sterilizers and related operations. For example, for large sources, ethylene oxide must be reduced by 99.99% compared to the EPA’s NESHAP requirements ranging from 99% to 99.94%, depending on the source of the emission (e.g. sterilization chamber vent or aeration). Alternatively, a large source can comply with an absolute limit of 10 parts per billion, the lowest concentration limit of ethylene oxide ever proposed.
The proposed amendments require stack Continuous Emission Monitoring (CEMS) for large sources. Fenceline monitoring is also required in the proposed amendments for large sources. The fenceline monitoring requirement however is terminated once the stack CEMS is operational. Large sources must conduct fenceline monitoring using either canister collection and analysis by TO-15 / TO-15A or conduct continuous fenceline monitoring using real time monitoring. TO15 or TO-15A sampling would be conducted on a once every six-day schedule. If a facility uses a real-time monitor and measures an ethylene oxide 3-hour average concentration that exceeds the certain thresholds, the facility must initiate the collection of canister samples at the monitoring location.
Prior to initiating the fenceline program the proposed amendments require the creation of a fenceline monitoring plan. Until the plan is approved the facility must conduct mobile monitoring at the fenceline of the facility at least once per month. The facility has the option to hire SCAQMD or a third party contractor (such as Montrose) to conduct the mobile monitoring.
The table that follows summarizes a portion of the main requirements of the proposed amendments:
|
Rule 1405 Classification
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Control Device Requirements
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Facility Wide Requirements
|
PTE
|
Stack CEMS
|
Interim Mobile Monitoring
|
Interim Fenceline Monitoring
|
|---|---|---|---|---|---|---|
|
> 2,000 pounds per year
|
99.99% or 10 ppb concentration limit
|
0.015 lbs/hr or emissions based upon 99.99% control
|
Yes
|
Yes
|
Yes
|
Yes
|
|
400 to 2,000 pounds per year
|
99.9% or 10 ppb concentration limit
|
NA
|
Yes
|
No
|
No
|
No
|
|
4 to 400 pounds per year
|
99.9% or 10 ppb concentration limit
|
NA
|
Yes
|
No
|
No
|
No
|
|
Post-Aeration Storage Facility Requirements
|
95%
|
NA
|
No
|
No
|
No
|
No
|
|
Warehouse Requirements
|
NA
|
NA
|
No
|
No
|
No
|
See note below
|
Note: The owner and operator of a warehouse must either conduct fenceline monitoring or perform an emissions study.
Curtailment
The proposed amendments also provide provisions for curtailment of operations should fenceline monitoring results be above certain thresholds. Curtailment means a reduction in the amount of usage of ethylene oxide which of course would limit production at the facility. Curtailment is based upon the daily usage and if enough fenceline monitoring samples exceed the trigger thresholds, ethylene oxide usage can be curtailed to zero.
How can Montrose help?
Montrose is uniquely qualified to assist a facility in complying with nearly all aspects of the proposed rule including:
- Montrose can install Stack CEMS with detection limits well under 1 ppb as required in the rule.
- Montrose can conduct fenceline monitoring using the Montrose owned laboratory Enthalpy Analytical, who pioneered canister sampling and analysis for EtO at low levels
- Montrose can conduct mobile monitoring using our state of the art PTR-TOF-MS equipped mobile platform
- Montrose can conduct Leak Detection and Repair (LDAR) programs
- Montrose can install indoor Air Quality (iAQ) monitoring systems with detection limits well under 1 ppb