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.

December 7, 1999



SUBJECT:        Requirements for Exposure Monitoring Under the Coke
                Oven Emissions Standard, 29 CFR 1910.1029(e)(1)(iii)

In 1998, The Directorate of Technical Support granted relief to three companies (U.S. Steel, LTV Steel Company, and Bethlehem Steel) which effectively reduced the number of personal samples to be taken by these companies as required under the Coke Oven Emissions Standard, 29 CFR 1910.1029. Paragraph (e)(1)(iii) of this standard requires the employer to conduct full-shift personal sampling for each battery and job classification on each shift. This sampling is to be conducted quarterly. The three aforementioned companies applied for relief from this provision of the standard and sought to reduce personal exposure monitoring for coke oven emissions from every shift to a single shift.

This allowance was granted based upon employer- and industry-generated data which demonstrated no substantial difference in exposures among the three shifts. Therefore, citations for violations of paragraph (e)(1)(iii) are to be classified as de minimis for these employers when specific conditions are met. Briefly, these conditions are that the companies must conduct exposure monitoring using the "worst-case" shift or use the representative-sampling procedure specified in paragraph (d)(1)(iv) of the 1,3-Butadiene Standard. The employer may use this representative-sampling procedure only when, (1) the shifts have similar operational and employee-exposure conditions, and (2) the employer has thoroughly and accurately documented these similarities. (Please refer the to attached letter to Mr. Terence M. Civic, LTV Steel Company, Inc., for further information.)

At the time that this relief was granted, OSHA was planning to reopen rulemaking on this standard to re-examine this issue, among others. We have since learned that this standard will not be reopened for rulemaking. Therefore, by way of this memorandum, we are altering our enforcement procedures.

Compliance Officers conducting inspections under this standard are instructed to verify the employer-generated data by conducting full-shift employee sampling. This sampling must be conducted on the shift which is expected to have the highest exposures. Consultation with the employer and employees/employee representatives will be used to make this determination.

Sampling results which are substantially higher than the employer-generated data establishes a serious violation of the requirements of 29 CFR 1910.1029(e)(1)(iii) and the employer shall be so cited. The Directorate of Technical Support should be contacted if assistance is needed to determine whether sampling results are to be considered "substantially higher" than the employer-generated data.

Thank you for your attention to this matter. Inquiries regarding this policy can be directed to the Office of Health Compliance Assistance at 202-693-2190.



July 17, 1998

Mr. Terence M. Civic
Manager of Safety and Environmental Health Services
LTV Steel Company, Inc.
200 Public Square
Post Office Box 6778
Cleveland, Ohio 44101

Dear Mr. Civic:

This letter is in response to your inquiry of April 17, 1998 regarding the exposure-monitoring requirement specified in paragraph (e)(1)(iii) of 29 CFR 1910.1029, the Coke Oven Emissions standard. You requested that the Occupational Safety and Health Administration (OSHA) permit LTV Steel Company, Inc. (LTV) to reduce personal exposure sampling for coke oven emissions from every shift to a single shift, similar to the relief granted earlier by OSHA to U.S. Steel and Bethlehem Steel.

Until a proposal is published updating the exposure-monitoring requirements of the Coke Oven Emissions standard, OSHA has determined that violations of paragraph (e)(1)(iii) of the standard will be classified as de minimis when specific conditions are met. OSHA Instruction CPL 2.103 (page III-19) states that a de minimis violation can occur when "[a]n employer complies with the clear intent of the standard but deviates from its particular requirements in a manner that has no direct or immediate relationship to employee safety and health." A de minimis violation does not result in a monetary penalty, nor does it require abatement.

In this case, OSHA's determination regarding de minimis violations is based on the exposure monitoring requirements of substance-specific standards published recently by OSHA. Two of these standards, 1,3-Butadiene (29 CFR 1910.1051) and Methylene Chloride (29 CFR 1910.1052), specify exceptions to the requirement for multi-shift, personal-exposure sampling. In this regard, paragraph (d)(1)(iv) of the 1, 3-Butadiene standard states, "[W]here the employer can document that exposure levels are equivalent for similar operations on different work shifts, the employer need only determine representative employee exposure for that operation from the shift during which the highest exposure is expected." Paragraph (d)(1)(ii)(C) of the Methylene Chloride standard reads, "Personal breathing zone air samples taken during one work shift may be used to represent employee exposures on other work shifts where the employer can document that the tasks performed and conditions in the workplace are similar across shifts."

For both the 1, 3-Butadiene and Methylene Chloride standards, employers must document that: Similar operations exist across work shifts; and , using personal breathing zone air samples, the employees involved in these operations are exposed to similar levels of the regulated substance.1 When these conditions have been met and properly documented, the 1, 3-Butadiene standard requires that exposures from the "worst-case" shift be monitored, while the Methylene Chloride standard permit exposures from any shift to be monitored on the assumption that "the tasks performed and conditions in the workplace are similar across shifts."

The requirements of the 1, 3-Butadiene standard appear to apply to LTV's situation in that every operation conducted during each of the non-daylight shifts may be similar to operations that occur during the daylight shift in terms of equipment and processes used, tasks performed, and employee exposure levels. The daylight shift, however, includes maintenance operations that are not performed during the non-daylight shifts. Consequently, the daylight shift would appear to be the "worst-case" shift. In this regard, the exposures of employees involved in maintenance operations must be monitored in full compliance with paragraph (e) of the Coke Oven Emissions standard because the employees appear to perform their tasks only during a single shift.2

In summary, LTV can use the representative-sampling procedure specified in paragraph (d)(1)(iv) of the 1, 3-Butadiene standard (or any other appropriate substance-specific standard published by OSHA) only when the shifts involved in the procedure have similar operational and employee-exposure conditions, and these similarities have been thoroughly and accurately documented. To ensure compliance uniformity among the employers who have sought relief from the exposure-monitoring provision of the Coke Oven Emissions standard, copies of this letter will be sent to U.S. Steel and Bethlehem Steel. If you have any questions regarding this matter, please contact Ms. Jennifer Silk, Director of the Office of Technical Programs and Coordination Activities, at (202) 219-7056.


Steven F. Witt
Directorate of Technical Support

Footnote(1) Note that OSHA interprets the term "condition" in the Methylene Chloride standard to include exposure levels. [Back to text]

Footnote(2) This conclusion assumes that no cross-contamination involving coke oven emissions has occurred between the maintenance operations and other operations conducted during the daylight shift. If cross-contamination occurs, then representative sampling cannot be used to estimate any employee exposures during the daylight shift; in such an instance, the requirement in paragraph (d)(1)(iv) of the 1, 3-Butadiene standard that "exposure levels [be] equivalent for similar operations" cannot be met. [Back to text]