To maintain certification these laboratories participate in a Proficiency Testing Program (PAT). The PAT issues samples twice a year and it is sponsored by Omega Specialty. "Spiked samples" of aerosol and vapor HDI , MDI and TDI are prepared by the IRSST in Montreal, Quebec, Canada . Twice a year, in the spring, 2,6 TDI and HDI Oligomer and Monomer samples are sent to the participating laboaratories. In the fall, 2,4-TDI and MDI Oligomer and Monomer. The results are compiled using the same criteria as AIHA Laboratory accreditation uses. The results are posted below.

The list of certified laboratories in alphabetical order is as follows.

A (*) next to the name of the laboratory indicates that they accept samples for a fee.

Information is correct as of 09/10/02