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Industrial Hygiene and Workplace Monitoring

Erin Dickison

Worker safety is of utmost importance. Occupational health and safety professionals, called industrial hygienists, use chemical sampling and analysis to assess workplace chemical concentrations and the potential for worker exposures. The validity of an assessment is based in part on the procedures used for sample collection and analysis, and on data interpretation. In many instances, industrial hygienists use approaches that have been refined over many years and are accepted by professionals as good practice. However, the multitude of variables within a specific workplace requires the professional to exercise judgment in the design of a particular assessment.

Worker Safety and Occupational Exposure Levels

Occupational Exposure Limits (OELs) are intended to set the airborne concentrations of substances to which workers can be exposed on a daily basis without significant risk of adverse effects from the material. OELs are normally set for an eight hour day and are expressed as an eight hour time-weighted average. In many cases, a short-term (15-minute) exposure limit or Ceiling (C) value is also established.

The primary regulatory and professional organizations that establish OELs for airborne aliphatic diisocyanates include:

Note: The Occupational Safety and Health Administration (OSHA) has not established Permissible Exposure Limits (PELs) for aliphatic diisocyanates.

HDMI0.005 (8-hr TWA)0.010 (C)
1,6-HDI0.005 (8-hr TWA)0.005 (8-hr TWA)
0.020 (STEL)
IPDI0.005 (8-hr TWA)0.005 (8-hr TWA)
0.020 (STEL)


C = Ceiling Limit (concentration that should not be exceeded during any part of the work shift)
TWA = Time Weighted Average (average airborne concentration over an 8-hour work shift)
STEL = Short Term Exposure Limit (15-minute average airborne concentration that should not be exceeded at any time during the work shift)
PPM = parts per million (0.020 ppm is equivalent to 20 parts per billion or 20 ppb; 0.005 ppm is equivalent to 5 ppb)

Current regulations should always be consulted for compliance purposes. To learn more about ADI concentration limits, consult with NIOSH, OSHA, or ACGIH, and the product manufacturer. To protect workers, the ADI industry uses many tools to monitor worker exposure as outlined below.

Industrial Hygiene & Workplace Monitoring Resources

OSHA Sampling & Analytical Methods
  • OSHA Analytical Methods - An index of sampling and analytical methods for chemicals that have either a validated or partially validated OSHA method
The following methods have been withdrawn by OSHA (for historical reference only):
Wipe Method

Note: Commercially available “isocyanate wipe testing” products are available for this sampling methodology. Additional information when considering Wipe Sampling is available here.

Additional sampling methods and information about diisocyanates can be found on OSHA’s website.

ASTM Standards

The American Society for Testing and Materials (ASTM) has developed several standards for testing of ADI. The following links are to summaries of test standards; the ASTM website provides information on how to order the full documents:

NIOSH Manual of Analytical Methods

NIOSH has developed a manual of analytical methods that it has evaluated. Chapter K of the manual discusses issues concerning sampling and analysis of airborne aliphatic diisocyanates. In addition, the manual provides the following analytical methods:

International Organization for Standardization (ISO): (for purchase)

Related Topics

In addition to industrial hygiene testing and reporting methodologies designed to protect worker health, there is a variety of environmental monitoring and airborne emissions testing and reporting methodologies and requirements. Visit the Environmental Emissions Reporting and Testing section of this website for information and resources on environmental airborne emissions reporting and testing.

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