OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

September 17, 1982

Mr. James R. Thornton
Manager of Industrial Hygiene
Newport News Shipbuilding
4101 Washington Avenue
Newport News, Virginia 23607

Dear Mr. Thornton:

This is in response to your inquiry of August 12, 1982, to MaryAnn Garrahan of my staff. You asked whether controls are available for monitoring a recirculation system as specified under 29 CFR 1910.1025(e)(4)(ii)(B) of OSHA's lead standard.

Various devices are available which monitor the effectiveness of a system for recirculating air in a workplace where there is lead xposure. Systems which would monitor specifically for lead dust, however, could be costly. One example of an acceptable system is a total dust monitor with an alarm that would trigger a bypass of the recirculated air at dust levels above, e.g., 5 µg/m3 at any concentration of lead in the dust. It provides protection in that no more than 10 percent of the permissible exposure limit (PEL) for lead would be permitted in the return air at any time.

29 CFR 1910.1025(e)(4)(ii)(B) is only enforced when there is a potential hazard (e.g., where employee exposures could exceed the PEL for the lead standard, 50 µg/m3). Citations would generally not be issued for 1910.1025(e)(4)(ii)(B) when there is only a technical violation of the standard (e.g., employee exposures to lead are very low).

I hope this information is helpful.


Patrick R. Tyson, Director
[Directorate of Enforcement Programs]

[Corrected 6/2/2005]