Ventilation and atmospheric conditions

Under 1918.94(a)(1)(i) the CO concentration must be kept at or below 50 ppm as an eight-hour average and employees must be removed if CO exceeds a 100 ppm ceiling (200 ppm ceiling for Ro‑Ro operations). The standard for CO limits is stated in 1918.94(a)(1)(i).

• The eight‑hour average area level is 50 parts per million (ppm); any periods above 50 ppm must be offset by corresponding periods below 50 ppm to maintain the average.
• A ceiling exposure of 100 ppm requires removal of employees; Ro‑Ro operations may use a 200 ppm ceiling instead.

(See 1918.94(a)(1)(i).)

Under 1918.94(a)(1) the initial CO test must be taken within one half hour after engine start for deep tanks or refrigerated compartments, and no later than one hour after engine start in other cargo handling areas. This timing requirement is stated in 1918.94(a)(1).

• Tests must be performed in the area where employees are working by persons competent in the use of the test equipment and procedures.
• If monitoring shows concentrations above limits, further testing frequency is determined by the need to prevent exceedances.

Under 1918.94(a)(1)(ii) the employer must use supplementary means (for example portable blowers or other ventilation devices) to reduce CO concentrations to within allowable limits as determined by monitoring. The requirement is in 1918.94(a)(1)(ii).

• Supplementary ventilation must be selected and operated based on monitoring results showing natural and vessel ventilation are inadequate.
• Employers should document monitoring and corrective actions to show CO stays within the 50 ppm eight‑hour average and the applicable ceiling.

Under 1918.94(a)(2) and (a)(3) portable blower intakes and any exposed belt drives must be guarded, and the frames of portable blowers must be grounded at the current source with an equipment grounding conductor; when the vessel is the source, the grounding conductor must be bonded to the vessel structure. See 1918.94(a)(2) and 1918.94(a)(3).

• Guards protect employees from contact with blower intakes and belt drives.
• Grounding or bonding reduces electrical shock risk; electric cords must be free from visible defects as required by 1918.94(a)(3).

(Comply with both guarding and grounding steps before using portable blowers in enclosed spaces.)

Under 1918.94(a) atmospheric tests for CO must be made by persons competent in the use of the test equipment and procedures, and tests must be made in the area where employees are working. This competency and location requirement is stated in 1918.94(a).

• Competent means trained to use the specific monitoring instruments and to understand sampling procedures and action levels.
• Employers should document training and competency for personnel performing atmospheric testing.

Under 1918.94(b)(1)(i) and (ii) employers must determine whether the grain has been or will be fumigated at the elevator and whether the compartment or any cargo loaded earlier has been treated with a fumigant or other chemical. See 1918.94(b)(1).

• This determination can be by documentation, notification, or inspection and is required before beginning to handle bulk grain where employees may be present.
• If fumigation or treatment has occurred or is suspected, additional atmospheric testing under 1918.94(b)(2)–(3) is required.

Under 1918.94(b)(2) and (b)(3) atmospheric testing must be done after loading begins and before employees enter the compartment, and additional tests must be made as often as necessary to ensure hazardous concentrations do not develop. This is required by 1918.94(b)(2) and 1918.94(b)(3).

• Testing frequency should be based on hazard potential, fumigant properties, and monitoring results.
• Tests must be performed by a designated person familiar with the fumigant, procedures, and PPE as described in 1918.94(b)(3)(i).

Under 1918.94(b)(3)(ii) employees must be removed from a compartment if the fumigant concentration reaches the level specified as hazardous by the fumigant manufacturer or exceeds the permissible exposure limits in 29 CFR part 1910, subpart Z, whichever is lower. The removal requirement appears in 1918.94(b)(3)(ii).

• Employers must monitor and compare measured concentrations to both the manufacturer’s hazard level and applicable PELs in 1910 Subpart Z.
• Reentry is permitted only after tests prove the atmosphere is within allowable limits.

Under 1918.94(b)(3)(iii)–(iv) no employee may enter a compartment treated with fumigants (or an adjacent compartment) until testing shows the atmosphere is within allowable limits; if entry into a compartment with hazardous or unknown concentrations is necessary for testing or emergencies, each entrant must use respiratory protection per 1918.102 and any PPE recommended by the fumigant manufacturer, and at least two observers must be stationed outside to provide rescue. See 1918.94(b)(3)(iii) and 1918.94(b)(3)(iv).

• Respiratory protection must follow 1918.102.
• Observers must be equipped with similar PPE and be ready to perform rescue, and emergency equipment must be readily accessible (1918.94(b)(3)(v)-(vi)).

Under 1918.94(b)(3)(i) the designated person conducting fumigant concentration tests must be thoroughly familiar with the fumigant’s characteristics, correct measurement procedures, proper measuring equipment, manufacturer recommendations and warnings, and appropriate PPE for the hazard. This requirement is found in 1918.94(b)(3)(i).

• The designated tester should have documented training on the specific fumigant and monitoring instruments.
• Employers should maintain records showing the tester’s qualifications and training.

Under 1918.94(b)(4) the employee applying a chemical (other than a fumigant) and any employees entering the treated compartment must be provided with and required to use any PPE recommended by the product manufacturer to protect against exposure. The PPE requirement is stated in 1918.94(b)(4).

• Follow the product label and manufacturer instructions for respiratory protection, gloves, coveralls, or other equipment.
• Employers must ensure PPE is used correctly and maintained.

Under 1918.94(c) the employer must not load break‑bulk tobacco until the carrier provides written notification whether the cargo has been fumigated; if treated with a toxic fumigant, loading cannot begin until a written warranty from the fumigation facility confirms aeration has reduced the fumigant to the manufacturer’s hazardous level or below the PELs in 1910 Subpart Z. This requirement is in 1918.94(c).

• The notification and warranty must be kept for at least 30 days after loading completion and be available for inspection.
• Employers should file and store the written documents to demonstrate compliance.

Under 1918.94(d) employers must determine that fumigant concentrations are within the level specified as hazardous by the fumigant manufacturer or do not exceed the permissible exposure limits of 29 CFR part 1910, subpart Z, whichever is lower, before loading or discharging such fumigated cargo. See 1918.94(d).

• This means testing and comparing results to both the manufacturer’s hazard levels and OSHA PELs.
• If concentrations exceed the lower of the two, do not permit employee entry or handling until the atmosphere is safe.

Under 1918.94(e) employees exposed to grain dust concentrations greater than the allowable limits in 1910 Subpart Z must be protected by suitable respiratory protective equipment as required by 1918.102. This is stated in 1918.94(e).

• Employers must follow 1918.102 for respirator selection, fit testing, training, and maintenance.
• Whenever feasible, dust controls and housekeeping should be used to reduce exposures before relying solely on respirators.

Under 1918.94(f)(2)–(4) holds for menhaden must be tested for hydrogen sulfide and oxygen deficiency before personnel enter and as often thereafter as necessary; employees must not enter when hydrogen sulfide exceeds a 20 ppm ceiling or when oxygen is less than 19.5 percent except in emergencies. These requirements are in 1918.94(f)(2) and 1918.94(f)(4).

• Tests must be made by designated supervisory personnel trained and competent in these hazards and test equipment as required by 1918.94(f)(3).
• If levels are above limits, do not enter except for emergency with appropriate PPE and rescue procedures.

Under 1918.94(f)(3) designated supervisory personnel who are trained and competent in the nature of the hazards and the use of test equipment and procedures must perform the hydrogen sulfide and oxygen tests. The personnel and training requirement is in 1918.94(f)(3).

• Competency includes understanding H2S hazards, O2 measurement, instrument calibration, sampling techniques, and emergency response.
• Employers should document training and designation of these supervisory testers.

Under 1918.94(f)(4) employees shall not enter a hold when the hydrogen sulfide level exceeds a 20 ppm ceiling or when the oxygen content is less than 19.5 percent, except in emergencies. The exact limits are in 1918.94(f)(4).

• A 20 ppm H2S ceiling means any measurement above that level requires removal and no entry.
• Oxygen below 19.5% is considered oxygen deficient and prohibits entry except for emergency operations with controls and PPE.

Under 1918.94(b)(3)(v)–(vi) one or more employees on duty must be equipped and trained to provide any specific emergency medical treatment required for the particular fumigant, and emergency equipment must be readily accessible wherever fumigated grains are handled. These provisions are in 1918.94(b)(3)(v)-(vi).

• Emergency equipment should match the fumigant manufacturer’s recommendations (e.g., antidotes, eyewash, decontamination supplies).
• Employers must train personnel in emergency medical procedures and maintain immediate access to the necessary equipment.

Under 1918.94(c) and (d) employers must obtain and retain written notification and warranties for fumigated tobacco (kept for at least 30 days) and must determine by testing that other fumigated cargoes meet manufacturer or 1910 Subpart Z limits before handling, documenting results as needed. See 1918.94(c) and 1918.94(d).

• Keep written fumigation warranties and notifications for 30 days after loading completion as required by 1918.94(c).
• Maintain testing records showing atmospheres are within allowable limits before permitting employee entry.

Under 1918.94(b)(3)(iv) and 1918.102 respirators are required for any employee entering a compartment containing hazardous or unknown concentrations of fumigants for testing or emergencies, and respirator use must follow the provisions in 1918.102. See 1918.94(b)(3)(iv).

• Employers must implement the respirator program elements in 1918.102 such as medical evaluations, fit testing, training, and maintenance.
• Use PPE recommended by the fumigant manufacturer in addition to respiratory protection when required.

Under 1918.94(a)(1)(ii) if natural and vessel ventilation are inadequate to keep CO within allowable limits, the employer must use supplementary means determined by monitoring to bring concentrations within limits, and employees must be removed if concentrations exceed the applicable ceiling in 1918.94(a)(1)(i).

• Implement additional mechanical ventilation (portable blowers), change engine operations, or stop engine use until CO is controlled.
• Ensure monitoring is frequent enough and done by competent testers to verify effectiveness.