Table 1 to Paragraph (d)(3)-Periodic Monitoring Requirements Based on Initial Exposure Monitoring Results
Air concentration condition observed during initial exposure monitoring | Periodic monitoring requirement |
If the initial exposure monitoring concentration is below the ECEL action level and at or below the EPA STEL | ECEL and EPA STEL periodic monitoring at least once in every 5 years. |
If the initial exposure monitoring concentration is below the ECEL action level and above the EPA STEL | ECEL periodic required at least once every 5 years, and EPA STEL periodic monitoring required every 3 months. |
If the initial exposure monitoring concentration is at or above the ECEL action level and at or below the ECEL; and at or below the EPA STEL | ECEL periodic monitoring every 6 months. |
If the initial exposure monitoring concentration is at or above the ECEL action level and at or below the ECEL; and above the EPA STEL | ECEL periodic monitoring every 6 months and EPA STEL periodic monitoring every 3 months. |
If the initial exposure monitoring concentration is above the ECEL and below, at, or above the EPA STEL | ECEL periodic monitoring every 3 months and EPA STEL periodic monitoring every 3 months. |
If 2 consecutive monitoring events have taken place at least 7 days apart that indicate that potential exposure has decreased from above the ECEL to at or below the ECEL, but at or above the ECEL action level | Transition from ECEL periodic monitoring frequency from every 3 months to every 6 months. |
If 2 consecutive monitoring events have taken place at least 7 days apart that indicate that potential exposure has decreased to below the ECEL action level and at or below the EPA STEL | Transition from ECEL periodic monitoring frequency from every 6 months to once every 5 years. The second consecutive monitoring event will delineate the new date from which the next 5-year periodic exposure monitoring must occur. |
If the owner or operator engages in any conditions of use described in paragraph (a) of this section and is required to monitor either the ECEL or EPA STEL in a 3-month interval, but does not engage in any of those uses for the entirety of the 3-month interval | The owner or operator may forgo the upcoming periodic monitoring event. However, documentation of cessation of use of methylene chloride must be maintained, and initial monitoring is required when the owner or operator resumes or starts any of the conditions of use described in paragraph (a) of this section. |
Owner or operator engages in any conditions of use described in paragraph (a) of this section and is required to monitor the ECEL in a 6-month interval, but does not engage in any of those uses for the entirety of the 6-month interval | The owner or operator may forgo the upcoming periodic monitoring event. However, documentation of cessation of the condition(s) of use must be maintained until periodic monitoring resumes, and initial monitoring is required when the owner or operator resumes or starts any of the conditions of use described in paragraph (a) of this section. |
40 C.F.R. §751.109