Acrylonitrile scope and application

This standard applies to all occupational exposures to acrylonitrile (AN) except for the limited exemptions described in the standard. See 1910.1045(a)(1) and the exemption provisions in 1910.1045(a)(2).

• Practical note: If AN is present in your workplace in any form that could expose employees, the standard applies unless you can rely on one of the specific exemptions in 1910.1045(a)(2).

Yes — finished polymers and products fabricated from them listed in the standard are exempt when in that finished-polymer form. See 1910.1045(a)(2)(i), which specifically lists ABS resins, SAN resins, nitrile barrier resins, solid nitrile elastomers, and acrylic and modacrylic fibers in their finished polymer form as outside the scope of the AN standard.

• Practical tip: The exemption applies only when the material is a finished polymer or a product fabricated from a finished polymer — not during processing or when monomer can be released.

An employer can rely on objective data to claim an exemption only if that data reasonably demonstrates the material will not release AN into the air above 1 ppm (8-hour TWA) under the expected worst-case processing, use, and handling conditions. See 1910.1045(a)(2)(ii) and the recordkeeping requirement in 1910.1045(a)(3).

• You must keep the objective data and the basis for relying on it as required by 1910.1045(q).

A solid material made from or containing AN is exempt only if it will not be heated above 170 °F during handling, use, or processing. See 1910.1045(a)(2)(iii).

• Practical implication: If your operation involves heating a solid AN-containing product above 170 °F, you cannot rely on this exemption and must comply with the standard.

The action level for acrylonitrile (AN) is 1 part per million (1 ppm) as an 8-hour time-weighted average, and AN is defined as the acrylonitrile monomer CH2=CHCN. See 1910.1045(b).

• Use this action level to trigger monitoring and certain required protections under the standard.

The employer must ensure employee inhalation exposure to AN does not exceed 2 ppm as an 8-hour time-weighted average (TWA) and does not exceed 10 ppm averaged over any 15-minute period (ceiling). See 1910.1045(c) and 1910.1045(c)(1)(ii).

• Action levels (1 ppm) are lower than the PEL and trigger monitoring and other requirements.

No — the employer must ensure employees are not exposed to skin contact or eye contact with liquid AN. See 1910.1045(c)(2).

• Controls should include work practices, PPE, and decontamination procedures to prevent skin and eye contact.

Airborne exposure measurements must come from air samples representative of each employee's exposure over an 8-hour period, and 'employee exposure' is defined as the exposure that would occur if the employee were not using a respirator. See 1910.1045(e)(1)(i) and 1910.1045(e)(1)(ii).

• In practice: do personal, full-shift samples for the job the employee actually performs and don't count respirator protection when determining exposure for compliance purposes.

Employers must initially monitor each workplace where AN is present to determine employee exposures and then follow the frequency rules based on the results: if exposures are below the action level, monitoring may be discontinued; if exposures are at or above the action level but at or below the PEL, repeat monitoring at least every 6 months until two consecutive measurements (≥7 days apart) are below the action level; if exposures exceed the PEL, repeat monitoring at least quarterly until two consecutive measurements (≥7 days apart) are at or below the PEL, then monitor at least every 6 months. See 1910.1045(e)(2) and 1910.1045(e)(3).

• Keep clear records of the dates and results to demonstrate compliance and to determine the next monitoring dates.

Employers must do additional monitoring whenever changes (production, process, control, personnel) or other reasons could increase AN exposures, and must notify affected employees of monitoring results within 15 working days either individually in writing or by posting; if results exceed the PEL the notice must state the PEL was exceeded and describe corrective actions. See 1910.1045(e)(4) and 1910.1045(e)(5)(i)-(ii).

• Practical step: prepare a template notice that includes the result, whether it exceeds the PEL, and planned corrective measures to save time and ensure timely notification.

Measurement methods must achieve a 95% confidence level accuracy within ±35% for concentrations at or above the PEL and within ±50% for concentrations below the PEL. See the measurement accuracy requirement in the standard (measurement accuracy is described in the methodology section of 1910.1045 and related subparagraphs) and refer to 1910.1045(e)(6) for measurement accuracy context.

• Use validated sampling and analytical methods that meet these performance criteria when documenting exposures.

An employer must establish regulated areas where AN concentrations exceed the permissible exposure limits, demarcate and segregate them to minimize the number of exposed persons, limit access to authorized persons, and prohibit food, beverages, tobacco use, and cosmetics in the area. See 1910.1045(f)(1)-(4).

• Make regulated-area boundaries clear (signs, physical barriers) and train authorized personnel on the access rules and prohibitions.

Employers must institute engineering and work practice controls to reduce and maintain AN exposures to or below the PELs except where infeasible; if such controls alone cannot reduce exposures to the PELs, employers must still use them to lower exposures as much as possible and supplement with respirators that meet the requirements of [1910.1045(h)]. See 1910.1045(g)(1)(i)-(ii).

• Priority: first implement engineering/work-practice changes; respirators are a supplement when controls cannot achieve the PEL.

The employer must have and implement a written program to reduce exposures to or below the PELs using engineering and work practice controls that: describe operations causing exposures above the PELs, outline the controls and practices to be applied, report technologies considered, provide a schedule (completed no later than November 2, 1980) and include other relevant information; the plan must be available upon request and updated at least annually. See 1910.1045(g)(2)(ii)-(v).

• Keep the written plan on-site and revise it yearly or sooner if conditions change.

Employers must implement a respiratory protection program that complies with the applicable provisions of 1910.134(b)-(d) and (f)-(m) for each employee required to use a respirator under the AN standard. See 1910.1045(h)(2)(i).

• This includes fit testing, medical evaluation, training, inspection, maintenance, and recordkeeping as required by 1910.134.

If air-purifying cartridges or canisters are used for AN, the canister or cartridge must be replaced prior to the end of its service life or at the end of each shift, and a label must be attached indicating the date and time it was first installed. See 1910.1045(h)(2)(ii)(A)-(B).

• Practical action: establish cartridge change schedules and labeling procedures in your respirator program to meet these requirements.

Employers must select and provide the respirators specified in 1910.134(d)(3)(i)(A) for routine use; for escape, provide any organic vapor respirator or any self-contained breathing apparatus permitted by [1910.134(d)(3)(i)(A)]. See 1910.1045(h)(3)(i)-(ii).

• Work with a qualified industrial hygienist to select approved respirators appropriate to the measured exposures and conditions.

A written emergency plan is required for each workplace where liquid AN is present; appropriate portions of the plan must be implemented in an emergency. See 1910.1045(i)(1)(i).

• The plan should include procedures for spills, evacuations, medical response, required PPE, and notification of emergency responders.

Decontamination means treating materials and surfaces by water washdown, ventilation, or other means to ensure they will not expose employees to airborne concentrations of AN above 1 ppm. See the definition of decontamination in 1910.1045(b).

• Ensure decontamination procedures are effective and monitored so that employees are not re-exposed when handling or disposing of contaminated materials.

An employer relying on the exemption in 1910.1045(a)(2)(ii) must maintain records of the objective data and the basis for relying upon that data as provided in 1910.1045(a)(3) and the recordkeeping provisions in 1910.1045(q).

• Records should document the data source, conditions represented, rationale for applicability to your operations, and be retained as the standard requires so you can demonstrate the exemption if inspected.

No — employee exposure for compliance purposes is defined as the exposure that would occur if the employee were not using a respirator, so respirator use cannot be counted to reduce the measured exposure when determining compliance. See 1910.1045(e)(1)(ii).

• This means engineering and work-practice controls must be used first to meet PELs; respirators are supplemental where controls are insufficient.

No — the employer must ensure food and beverages are not present or consumed, tobacco products are not present or used, and cosmetics are not applied in a regulated area. See 1910.1045(f)(4).

• Provide clearly designated clean areas outside the regulated area for eating and personal activities.

The written notice must include a statement that the permissible exposure limits were exceeded and a description of the corrective action being taken to reduce exposures to or below the PEL. See 1910.1045(e)(5)(ii).

• Be specific about the corrective measures and expected timeline so affected employees understand what steps are being taken and when.

An 'authorized person' is someone specifically authorized by the employer whose duties require entry into a regulated area, or a designated employee representative entering to observe monitoring procedures under paragraph (r). See the definition of 'authorized person' in 1910.1045(b).

• Only train and authorize those who must enter regulated areas and ensure they understand required PPE, decontamination, and access controls.

Employees correcting an AN emergency must be equipped as required in paragraph (h) until the emergency is abated. Employers must supply and ensure use of the protective equipment specified by the emergency plan in 1910.1045(h).

• This is a mandatory requirement under 1910.1045(i)(1)(ii).
• Ensure your emergency procedures identify the exact PPE, respirators, and other controls called for in 1910.1045(h) and that affected employees are trained to don and use them.

Employees not engaged in correcting the emergency must be evacuated from the area and not be permitted to return until the emergency is abated. This is required by 1910.1045(i)(1)(iii).

• Employers should have evacuation and accountability procedures in the emergency plan and ensure alarms and notifications are used to remove nonessential personnel promptly.

A general alarm must be installed and used where there is the possibility of employee exposure to acrylonitrile in excess of the ceiling limit. See 1910.1045(i)(2).

• The alarm must promptly alert employees to occurrences that could push airborne AN above the ceiling limit so they can take emergency actions.
• Document alarm locations, response actions, and testing frequency in your emergency procedures.

Where eye or skin contact with liquid acrylonitrile may occur, the employer must provide impermeable protective clothing or equipment at no cost to the employee and assure employees wear it. See 1910.1045(j)(1).

• The employer must also comply with the general PPE rules in 1910.132 and eye/face protection in 1910.133.
• Examples include impermeable gloves, coveralls, aprons, boots, and splash goggles or face shields appropriate to the task.

The employer must clean, launder, maintain, or replace required protective clothing and equipment as needed to maintain effectiveness, and must ensure impermeable protective clothing that contacts liquid AN is decontaminated before the employee removes it. See 1910.1045(j)(2)(i) and 1910.1045(j)(2)(ii).

• Establish procedures for on-site decontamination before doffing and for laundering or safe disposal off-site.
• Replace damaged or worn PPE immediately to preserve protection.

If an employee’s nonimpermeable clothing becomes wetted with liquid AN, the employer must assure the employee immediately removes that clothing and proceeds to shower, and the clothing must be decontaminated before being removed from the regulated area. This is required by 1910.1045(j)(2)(iii).

• Provide immediate shower facilities and train employees to act without delay.
• Keep contaminated clothing in designated, labeled containers until decontamination or disposal is completed.

Only employees authorized to remove protective clothing or equipment for laundering, maintenance, or disposal are allowed to remove it from the change room. Employers must assure this limitation under 1910.1045(j)(2)(iv).

• Maintain controls and records of who handles contaminated clothing to prevent unsecured removal and possible exposure to others.

The employer must inform any person who launders or cleans protective clothing or equipment of the potentially harmful effects of exposure to acrylonitrile. See 1910.1045(j)(2)(v).

• Provide written notification and handling/decontamination instructions to external laundry services or internal laundry staff.

All surfaces must be maintained free of visible accumulations of liquid acrylonitrile. This housekeeping requirement is stated in 1910.1045(k)(1).

• Regular cleaning schedules and inspections help ensure compliance and reduce skin/contamination hazards.

For operations involving liquid acrylonitrile, employers must institute a program for detecting leaks and spills, including regular visual inspections, as required by 1910.1045(k)(2).

• Document inspection frequency, methods, and corrective actions; train employees to recognize and report leaks or spills promptly.

When spills of liquid acrylonitrile are detected, employers must assure that surfaces contacted by the liquid are decontaminated, and employees not engaged in decontamination must leave the area and not be permitted back until decontamination is completed, per 1910.1045(k)(3).

• Establish trained spill-response teams, use appropriate PPE, and post signs or barriers preventing unauthorized re-entry during cleanup.

Acrylonitrile waste, scrap, debris, bags, containers, or equipment must be decontaminated before being incorporated into the general waste disposal system, as required by 1910.1045(l).

• Coordinate decontamination and disposal with environmental regulations and keep records proving decontamination occurred prior to general disposal.

If employees are exposed to airborne concentrations of acrylonitrile above the permissible exposure limits, or if employees are required to wear protective clothing under paragraph (j), the employer must provide the facilities required by 29 CFR 1910.141, including clean change rooms and shower facilities, and must assure employees use them. See 1910.1045(m)(1) and 1910.141.

• Make facilities available at no cost and ensure they are maintained and accessible when needed.

Employees who wear protective clothing for protection from skin contact with liquid AN must shower at the end of the work shift, and any employee with skin or eye exposure to liquid AN must shower immediately to minimize skin absorption, per 1910.1045(m)(2) and 1910.1045(m)(3).

• Ensure showers are reachable from work areas and train employees to use them without delay after an exposure.

Employees working in the regulated area must wash their hands and faces prior to eating, as required by 1910.1045(m)(4).

• Provide adequate washing facilities and signage reminding workers to wash before meals.

The employer must institute medical surveillance for each employee who is or will be exposed to acrylonitrile at or above the action level, without regard to respirator use, and must assure that examinations are performed by or under the supervision of a licensed physician and provided without cost to the employee, per 1910.1045(n)(1)(i) and 1910.1045(n)(1)(ii).

• Employers must offer and pay for exams and tests at initial assignment and periodically as required.

Initial examinations must include at least a work and medical history focused on skin, respiratory, gastrointestinal, and CNS symptoms; a complete physical exam emphasizing nervous, gastrointestinal, respiratory, skin, and thyroid systems; a standard-size posterior-anterior chest X-ray; and for workers 40 years or older (or if the physician deems appropriate) additional intestinal tract tests including fecal occult blood screening, as listed in 1910.1045(n)(2)(i)-(iv).

• Provide these elements at initial assignment or when the surveillance program is instituted.

Employers must provide the specified examinations at least annually for employees covered by the medical surveillance program and must make the exams available prior to termination if the employee has not had them within 6 months before leaving, as required by 1910.1045(n)(3)(i)-(ii). Additional examinations must be provided if an employee develops signs or symptoms that may be associated with AN exposure, per 1910.1045(n)(4).

• Have procedures to promptly schedule follow-up exams when symptoms arise and document compliance.

The employer must provide the physician a copy of the standard and its appendixes, a description of the employee's duties and representative exposure level, anticipated exposure (if relevant), PPE used, and prior medical information, as required by 1910.1045(n)(5). The employer must obtain a written opinion from the physician that includes results of exams/tests, whether the employee has conditions increasing risk from AN exposure, any recommended exposure or PPE limitations, and confirmation that the employee has been informed of results; the employer must instruct the physician not to reveal unrelated diagnoses and must provide the written opinion to the employee per 1910.1045(n)(6)(i)-(iii).

• Keep the physician’s opinion in the employee’s medical file and act on any recommended limitations.

Employers must train each employee exposed to AN above the action level, employees whose exposures are kept below the action level by controls, and employees subject to potential skin or eye contact with liquid AN; training must be provided at initial assignment and at least annually, and employers must make a copy of the standard and its appendixes readily available to affected employees, per 1910.1045(o)(1)(i), 1910.1045(o)(1)(ii), and 1910.1045(o)(2)(i).

• Training topics must include appendices A and B, quantities and locations of AN, PPE use and limits, medical surveillance, emergency procedures, and controls as listed in 1910.1045(o)(1)(ii)(A)-(G).

Yes — employers must include AN and AN-based materials in their Hazard Communication program and ensure employees have access to container labels and safety data sheets and are trained. See Requirement in 1910.1045(p)(1)(iii) which requires employers to include AN materials in the HCS program and provide access to labels and safety data sheets, and 1910.1045(p)(1)(i) which directs chemical manufacturers, importers, distributors and employers to comply with the Hazard Communication Standard at 1910.1200.

• Make sure each container of AN or AN-based material has required labeling and that copies of the safety data sheet (SDS) are available to all employees who may be exposed.
• Train employees on the hazards listed in 1910.1045(p)(1)(ii) (for example, cancer, CNS, liver, irritation, sensitization, acute toxicity, flammability) as part of HCS training.

Employers must post illuminated, legible signs at all workplaces where AN concentrations exceed the permissible exposure limits, using the specified legend. See 1910.1045(p)(2)(i) which requires posting signs to clearly indicate workplaces where AN exceeds the PEL, and 1910.1045(p)(2)(ii) which requires the signs be illuminated and cleaned as necessary so the legend is readily visible.

• Required legend (exact wording): DANGER ACRYLONITRILE (AN) MAY CAUSE CANCER RESPIRATORY PROTECTION MAY BE REQURED IN THIS AREA AUTHORIZED PERSONNEL ONLY
• Employers may not post statements that contradict or detract from the required sign per 1910.1045(p)(1)(iv).
• Note: a prior alternate legend was permitted before June 1, 2016; see 1910.1045(p)(2)(iii) if you are evaluating older signage.

Employers must affix precautionary labels to all containers of liquid AN and ensure those labels stay with the material when it leaves the workplace. See 1910.1045(p)(3)(i) which requires labels on all containers of liquid AN (unless exempted) and that the labels remain affixed when the materials are sold, distributed, or otherwise leave the employer's workplace.

• Labels must comply with the Hazard Communication requirements in 1910.1045(p)(1)(i) and be readily visible and legible per 1910.1045(p)(3)(iii).
• For historical context, employers could use an alternate shorter label before June 1, 2015; see 1910.1045(p)(3)(ii).

The employer must keep an accurate record of the objective data relied upon for the exemption and must retain that record for as long as the employer relies on the data. See 1910.1045(q)(1)(i) (requirement to establish and maintain the record) and 1910.1045(q)(1)(iii) (retention for the duration of reliance).

Required elements to include (minimum):

• The material qualifying for the exemption (1910.1045(q)(1)(ii)(A)).

• The source of the objective data (1910.1045(q)(1)(ii)(B)).

• Testing protocols and results or analysis showing release of AN (1910.1045(q)(1)(ii)(C)).

• A description of the exempted operation and how the data supports the exemption (1910.1045(q)(1)(ii)(D)).

• Also remember that records required by this section must be made available in accordance with 29 CFR 1910.1020 as described in 1910.1045(q)(4).

Exposure monitoring records must include full sampling details (dates, number, duration, results), methods used, respirator types if any, and the names and job classifications of monitored employees, and they must be kept at least 40 years (or employment plus 20 years, whichever is longer). See 1910.1045(q)(2)(ii) for the required record elements and 1910.1045(q)(2)(iii) for the retention period.

• Required record details include sampling dates, number, duration, results, description of sampling procedure (1910.1045(q)(2)(ii)(A)) and the sampling/analytical methods and evidence they meet the accuracy/precision requirements in 1910.1045(e)(6).
• Include type of respirators used (1910.1045(q)(2)(ii)(C)) and the employee names/job classifications represented by each sample (1910.1045(q)(2)(ii)(D)).

Yes — affected employees or their designated representatives must be given an opportunity to observe AN exposure monitoring, and employers must provide observers with required personal protective clothing and equipment if entry into a protected area is necessary. See 1910.1045(r)(1) which grants the right to observe monitoring, and 1910.1045(r)(2)(i) which requires employers to provide the observer with the personal protective clothing and equipment that employees in the area must wear.

• Observers are also entitled to an explanation of measurement procedures and to observe and record the steps and results of the airborne concentration measurements per 1910.1045(r)(2)(ii).
• Employers must ensure observers follow all applicable safety procedures while not interfering with the monitoring (1910.1045(r)(2)).