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Lab Safety: Lab Coat Requirements

Lab Safety Advisor, June 14, 2005

Did you know that OSHA has criteria for fabric that must be met before a lab coat can be declared personal protective equipment? OSHA compliance document CPL 2-2.69 states that fabric must meet the American Society for Testing and Materials (ASTM) requirements. Those requirements include water repellency or spray ratings, the Suter hydrostatic pressure test, air permeability and the break test. Each one of these tests can tell you how well the fabric is made, whether it will meet fluid resistance requirements from OSHA and how it will hold up under use and laundering.

Water repellency is the characteristic of fabric that resists wetting. Water is sprayed against the taut surface of a test specimen under controlled conditions, which produces a wetted pattern whose size depends on the relative repellency of the fabric. The evaluation is accomplished by comparing the wetted pattern to pictures on a standard chart. A superior fabric for a lab coat would be one with a water repellency of 90 or higher.

The Suter hydrostatic pressure test measures the resistance of fabrics to the penetration of water under static pressure. It is used primarily for the testing of heavy, closely woven fabrics such as those used in surgical suites. The results of this test depend on the water repellency of the fibers as well as the construction of the fabric. The Suter scale goes from 0 to 1,000 with impervious being 1,000. Suter hydrostatic scores of 860 are common with non-porous surgical material and scores of 24 are common with cotton/polyester-blend lab coats. A superior fabric for a lab coat would be one with a Suter hydrostatic score of 400 or more.

OSHA requires that employees wear PPE whenever there is a potential for spraying or splashing of blood or other potentially infectious material. Most lab employees work in room temperatures ranging from 60 to 75 degrees Fahrenheit vs., a surgical suite, which has controlled temperatures. Therefore, laboratory coats must have air permeability for comfort, which is important to employee satisfaction and ensures that employees wear the coats and are compliant with the OSHA requirements. Air permeability is measured in cubic feet per minute. Hospital surgical attire that is considered fluid proof has an air porosity of 1; cotton lab coats have an air porosity of 25. This means the cotton lab coat is cooler than the fluid-proof fabric required for hospital surgical attire. A superior fabric for a lab coat would be one with an air permeability of 10 cubic feet per minute or higher.

The break test is a measurement of the strength of the fabric. Unwashed fabric has the highest break strength. The more the fabric is washed and the conditions under which it is washed (i.e. detergent, fabric softener, bleach) determines the life of the garment. The break strength of cotton fabric is usually in the 50 to 60 pound range and a cotton/polyester blend is typically 80 pounds.

A superior fabric for a lab coat would be one with a break strength of 150 or more that holds up under 175 washings with less than a 5% decrease in break strength. What this means is that it will hold up and remain durable through repeated washings.

Remember to ask your lab coat vendor for written documentation to be sure the coat you purchase meets these requirements.