Standard Interpretations - Table of Contents|
| Standard Number:||1910.252(c); 1926.353|
March 22, 1995
MEMORANDUM FOR: R. DAVIS LAYNE REGIONAL ADMINISTRATOR REGION IV FROM: JOHN B. MILES, JR., DIRECTOR DIRECTORATE OF COMPLIANCE PROGRAMS SUBJECT: Sampling for Lead Welding Fumes
This is in response to your letter dated November 14, requesting a change in OSHA sampling policy for welding operations. While we can agree with much of your rationale, studies have shown that overall worker exposure to metal fume generated during welding is lower when measured inside the helmet compared to outside. The following references support this conclusion and are the basis for the OSHA sampling protocol requirements.
Johnson, W.S.: An investigation into the True Exposures of Arc
Welders by Means of Simultaneous Sampling Procedures. American Industrial
Hygiene Association Journal 20:194-196 (1959).
In addition, the most recent review commission decision (attachment) essentially mandates this requirement. OSHA therefore, will still require that personal sampling for welding fume be conducted with the filter placed inside the welding helmet.
The requirement for sampling outside a respirator when monitoring for lead in construction is primarily to evaluate the level of respiratory protection afforded the employee and the extent of the airborne exposure. As you indicated in your letter, the problem with sampling inside a welding helmet is that one could be precluded from applying the full lead standard if the exposure is below the permissible exposure limit (PEL). A sample taken under a welding helmet that was below the PEL would negate the personal hygiene requirements of the lead standard. To provide adequate worker protection from this scenario, one would need to conduct sampling both inside and outside the welding helmet. Sampling under the welding helmet would determine the need for medical monitoring, engineering controls, and respiratory protection. If the documented exposure inside the helmet was below the PEL and the sample outside was above it, the outside sample can be used to evaluate the hygiene requirements.
While this letter does not change the OSHA sampling policy for welding operations it does provide a solution for not adequately protecting workers. If you have any questions or wish to discuss this more please contact Richard Fairfax at (202) 219-8036.
Attachment [( OSHRC Docket No. 81-2089)]
November 14, 1995
MEMORANDUM FOR: JOHN P. MILES, Director Directorate of Compliance Programs FROM: R. DAVIS LAYNE Regional Administrator SUBJECT: Sampling for Lead Welding FumesRecently, Region IV received an adverse ALJ's decision in a contested case involving lead where high exposures were generated from welding and cutting on structures containing lead (Secretary v. TTX Company, Acorn Division, OSHRC Docket No. 93-33). The ALJ ruled that because OSHA did not collect air samples inside the welder's helmet, the sampling was flawed. The basis for the ALJ's decision was the agency's policy of requiring welding fume air samples to be collected inside the welder's helmet. More frequently, employers are using the basis for this decision to challenge OSHA's lead citations where any part of an employee's job may have lead exposures that were generated by welding, cutting or burning. These challenges could negatively impact on OSHA's enforcement of the construction lead standard since cutting and burning may be a large component of the construction activity.
We believe the policy of collecting lead welding fumes under the welder's helmet is contrary to the exposure monitoring requirements of the lead standards (1926.62 and 1910.1025). Under the lead standards, exposure is defined as the "exposure which would occur if the employee was not wearing a respirator." We will use a hypothetical example to show how contradictory, contrary, and less protective this welding fume sampling procedure can be for a welder exposed to lead.
This example will use a welder and an employee employed as a grinder. The grinder wears a hooded air supplied respirator. The grinder's 8-hour TWA exposure to lead measured outside the respirator is 58 micrograms per cubic meter. Inside the respirator, the grinder's exposure is measured as below the detection limit for lead. On the other hand, the welder's exposure outside the helmet is 60 micrograms per cubic meter. Since fume concentrations under the welder's helmet have been documented to be up to 40% less than those outside the helmet, the welder's lead exposure could be 36 micrograms per cubic meter under the helmet. Based on this scenario, OSHA could legally require the grinder to shower and remove his/her work clothes before leaving the work site. However, the welder would not be required to shower and remove his/her work clothing before leaving the job site. This employee would have a significant risk of ingesting lead. Also, the employee may carry the lead home and expose his/her family to lead. Clearly in this example, the welder receives significantly less protection from the ingestion hazards of lead.
The major weakness of applying OSHA's policy for sample collection for welding fumes to toxic metals such as lead is that it does not accurately measure the amount of toxic metal released into the work environment. For example, lead levels measured inside the welder's helmet underestimate the degree of lead contamination of the workplace and the potential ingestion hazard. Welding operations produces copious quantities of very small-sized fume particles. For lead, the fume particle size has been reported to range from 0.0001 to 1.0 micrometers. These small size particles will remain in the air for long periods of time. The fume particles that are not captured by local exhaust systems will disperse and eventually settle out on the workplace's surfaces. The movement of air, traffic, and other machinery can dislodge these particles and cause them to become airborne again. Additionally, settled lead particles are a potential source of contamination for clothing, hair and skin. Therefore, the potential for contaminating work surfaces should be assessed for toxic metal outside the welder's helmet.
Further, OSHA's decision to sample for toxic metal welding fumes inside the welder's helmet is not supported by consensus standards. The basis for OSHA adopting the policy of sampling inside the hood was the promulgation of the 1989 permissible exposure limit (PEL) for welding fumes. The standard adopted ACGIH's welding fumes TLV. ACGIH intended this TLV only to apply to fumes generated by the manual metal arc or oxyacetylene welding of iron, mild steel, or aluminum. The justification for the welding fume TLV is based on studies where air samples were taken inside the welder's helmet. ACGIH never intended for this TLV to apply to welding operations involving toxic metals such as lead.
The Office of Health Compliance Assistance has indicated that for all welding fume sampling, including toxic metals such as lead, samples should be collected inside the welder's helmet. We strongly recommend that OSHA's welding fume policy be changed. The policy should be modified to explicitly say that sampling inside the welder's helmet does not apply to toxic metals such as lead, cadmium, and arsenic. If this policy is not changed, we fear that many workers and their families may suffer needlessly from the toxic hazards posed by lead and other toxic metal fumes generated during welding, cutting, and burning operations.
If you have any questions, please call Sol Raines or Russ Dugger at (404) 347-2283.
Standard Interpretations - Table of Contents|