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Worker safety is important to the diisocyanates industry. 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.

Protecting Worker Health through Safe 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 material adverse effects. 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 is also established. Occupational exposure limits can be called by different names such as: threshold limit values (TLV); permissible exposure limits (PEL) and short-term exposure limit (STEL) in the United States; maximalearbeitplatzkonzentrationen (MAK) in Germany; and indicative and binding limit values (ILV) in the European Union.

Regulatory authorities in many countries have devised and adopted occupational exposure limits in the air for MDI and TDI. For MDI and TDI in the U.S., these are commonly 20 parts per billion (ppb) (short-term exposure limit) and 5 ppb (for eight-hour time-weighted average value). These OELs have been set by the Occupational Safety and Health Administration (OSHA) or the American Conference of Governmental and Industrial Hygienists (ACGIH). On February 1, 2016, the American Conference of Governmental Industrial Hygienists (ACGIH) lowered its recommended occupational exposure levels, known as TLVs, for Toluene-2,4-diisocyanate and Toluene-2,6-diisocyanate (TDI) from 5 parts per billion (ppb) to 1 ppb and the 15-min STEL from 20 ppb to 5 ppb. Current regulations should always be consulted for compliance purposes. To learn more about concentration limits for diisocyanates, consult with OSHA, ACGIH (or other country specific regulatory agencies) and the product manufacture. To protect workers, the DII industry uses many tools to monitor worker exposure as outlined below.

Industrial Hygiene and Workplace Monitoring Resources

American Chemistry Council

The American Chemistry Council’s Diisocyanates Panel and the Center for the Polyurethanes Industry provide helpful resources related to industrial hygiene air monitoring methods for MDI and TDI. Some of these include:

OSHA Sampling and Analytical Methods

The following methods have been fully validated by OSHA:

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

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 TDI. 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

The National Institute for Occupational Safety & Health (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 diisocyanates. In addition, the manual provides the following analytical methods:

International Organization for Standardization (ISO)

Related Topics

For additional information related to industrial hygiene and worker health, visit the  Air Monitoring and  Diisocyanate Biomonitoring pages.

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 Airborne Emissions Reporting and Testing section for information and resources on environmental airborne emissions reporting and testing.