Asbestos

High or Overloaded Outside Air Samples

One of my outside samples exceeded the indoor air standard (0.01 f/cc). What do I do now?

If you have an air sample outside of a containment, mini-containment or glove bag and its analytical results exceed the indoor air standard of 0.01 fiber per cubic centimeter of air (f/cc) or an alternative indoor air standard that you have established or if it is too heavily loaded with particulate to be analyzed one of the following two options must be undertaken.

Option 1: Assume the high or overloaded sample resulted from the asbestos-related work you are monitoring.

If you suspect the high or overloaded air sample is the result of the asbestos-related work you are monitoring, conduct the following steps:

For a Containment:

  1. Evacuate the area immediately adjacent to the asbestos work area.
  2. Examine the containment walls and critical barriers for any holes or separations and if there are any, repair them.
  3. Check the negative pressure to ensure it is at least -0.02 inches of water column("WC).
  4. Clean the area adjacent to the containment with HEPA-filter vacuums and wet wiping.
  5. Simultaneously collect five (5) air samples in the area where the high or overloaded sample occurred.
  6. Analyze the samples by Phase Contrast Microscopy (PCM) and if the results of all five samples are less than the indoor air standard (0.01 f/cc) or the alternative indoor air standard that you have established that the area may be reoccupied.
  7. If any of the results exceed the indoor air standard or the alternative indoor air standard that you have established, repeat Steps 1-6.

For a Glove bag or Mini-containment:

  1. Clean the area within 10 feet of the glove bag or mini-containment with HEPA-filter vacuums and wet wiping.
  2. Simultaneously collect two (2) air samples in the area where the high or overloaded sample occurred.
  3. Analyze the samples by PCM and if the results of both samples are less than the indoor air standard (0.01 f/cc) or the alternative indoor air standard that you have established the area may be reoccupied.
  4. If the results exceed the indoor air standard (0.01 f/cc) or the alternative indoor air standard that you have established, repeat Steps 1-3.

Option 2: If you suspect the high or overloaded sample resulted from nonasbestos-related activities in the area.

If you suspect the high or overloaded air sample is the result of nonasbestos-related activities in the area, conduct the following steps:

For a Containment:

  1. Delay evacuation of the area immediately adjacent to the asbestos work area.
  2. Immediately submit the air samples in question for Transmission Electron Microscope (TEM) analysis. Request results in f/cc.
  3. If the results of the samples are less than the indoor air standard (0.01 f/cc) the area may be reoccupied.
  4. If the results exceed the indoor air standard (0.01 f/cc), follow all the steps in Option 1.

For a Glove bag or Mini-containment:

  1. Immediately submit the air samples for TEM analysis. Request results in f/cc.
  2. If the results of the samples are less than the indoor air standard (0.01 f/cc) the area may be reoccupied.
  3. If the results exceed the indoor air standard (0.01 f/cc), follow all the steps in Option 1.

IMPORTANT: Samples that are too overloaded with particulate material and cannot be analyzed by PCM analysis may be too overloaded to perform TEM analysis. It is recommended you speak to the laboratory prior to having the samples analyzed.

How do I find out more information?

For more information about asbestos, contact the Asbestos Program at MDH through the internet or by telephone at (651) 201-4620.

Go to > top

Updated Wednesday, 03-Apr-2013 13:33:08 CDT