OSHA: Radon exposure unlikely for trench workers

Construction workers in open-air excavation or trenching worksites are not likely to be exposed to radon radiation above the permissible exposure limit, but workers in an enclosed space could be, OSHA said in a recent standard interpretation.

In an open-air environment such as a trench, radon gas levels generally are diluted through natural ventilation, but workers in a building, mine, cave or tunnel could be exposed to hazardous levels of radon that are artificially enhanced due to confinement. Radon testing at an excavation worksite generally would not be necessary unless the excavations are enclosed or in a geographical area known for high levels of radon, Richard Fairfax, director of OSHA's Directorate of Enforcement Programs, said in the letter.

The agency advises using OSHA's standards for ionizing radiation (1926.53 and 1910.1096) to determine if a given radon level may result in hazardous exposures; control measures can be found in 1926.651(g)(1)(ii).

Other recently released standard interpretations from OSHA include:

• Compliance with 1926.1101 when drilling through asbestos-containing floor tile/mastic
• Clarification on equivalent test nebulizer for qualitative fit tests
• Medical exams and blood testing for zinc protoporphyrin under OSHA's lead standards