11.6.2 Changes in Conditions

The frequency of periodic monitoring will change depending on whether exposure conditions have changed. See Table 11.2 below of specific criteria and prescribed actions. 

Table 11.2. Criteria for change in periodic monitoring frequency.

Criteria

Action

Exposure reduced to at or below ECEL (but above Action Level).

  • Two consecutive samples taken at least 7 days apart show an 8-hour TWA exposure to DCM has decreased from above the ECEL to between 1 ppm and 2 ppm.

Adjust periodic monitoring frequency from every 3 months to every 6 months.

Exposure reduced below the ECEL Action Level. Two consecutive samples taken at least 7 days apart show DCM exposure has decreased.

  • 8-hour TWA: Below 1 ppm (Action Level).
  • 15-minute exposure: At or below 16 ppm (EPA STEL).

 

Adjust periodic monitoring frequency from every 6 months to every 5 years.

Periodic monitoring will be suspended if DCM is no longer being used.

Maintain documentation confirming that the processes or tasks were not performed. Resume monitoring if DCM use is restarted

 

Chemical Hygiene Plan Menu