National Institute for Occupational Safety and Health (NIOSH)

NIOSH, the National Institute for Occupational Safety and Health, is the US federal research agency responsible for studying work-related injuries and illnesses and recommending ways to prevent them. NIOSH is part of the Centers for Disease Control and Prevention (CDC). Unlike OSHA, it conducts research and issues recommendations but does not enforce workplace safety laws.

Safety professionals rely on NIOSH research every day, often without realizing it. Exposure limits, respirator approvals, lifting guidelines and the widely used hierarchy of controls model all trace back to NIOSH work.

What Is NIOSH?

NIOSH was established by the Occupational Safety and Health Act of 1970, the same law that created OSHA. According to the CDC's About NIOSH page, the institute is part of the CDC within the US Department of Health and Human Services, and its mission is to develop new knowledge in occupational safety and health and transfer that knowledge into practice. NIOSH reports that it has more than 1,300 employees working across the United States.

The key distinction is that NIOSH and OSHA sit in different federal departments and have different jobs:

• NIOSH (Department of Health and Human Services) researches hazards, evaluates workplaces on request, trains professionals and publishes recommendations.
• OSHA (Department of Labor) writes and enforces legally binding standards, conducts inspections and issues citations.

In practice, NIOSH research frequently informs the standards OSHA later proposes, and OSHA often refers employers to NIOSH guidance where no specific standard exists.

What Does NIOSH Do?

NIOSH's work spans research, evaluation, certification and education. The areas most relevant to safety managers are described below.

Research on workplace hazards

NIOSH studies chemical, physical, biological, ergonomic and psychosocial hazards across industries such as construction, manufacturing, mining, agriculture, healthcare, oil and gas, and transportation. Its divisions include dedicated mining research groups in Pittsburgh and Spokane and a respiratory health division, among others.

Recommended Exposure Limits (RELs)

NIOSH develops Recommended Exposure Limits for hazardous substances. RELs are not legally enforceable, but they are often more protective than OSHA's Permissible Exposure Limits (PELs), many of which date from the early 1970s. Many industrial hygiene programs use the more protective of the two values as an internal target.

Respirator certification

NIOSH tests and approves respirators used in US workplaces. When OSHA's respiratory protection standard requires a respirator, it must be NIOSH-approved. The familiar "N95" designation is a NIOSH certification class, and approved products carry a NIOSH approval number on the device or packaging.

Health Hazard Evaluations

Through its Health Hazard Evaluation program, NIOSH can investigate a workplace to determine whether employees are exposed to hazardous materials or harmful conditions. Employers, employees or their representatives can request an evaluation. NIOSH then shares findings and recommendations. These evaluations are not inspections, and NIOSH does not issue citations or penalties.

Publications and tools

NIOSH publishes criteria documents, hazard alerts, workplace solutions sheets and reference tools such as the NIOSH Pocket Guide to Chemical Hazards. It also maintains the revised NIOSH lifting equation for evaluating manual lifting tasks.

Training and education

NIOSH funds Education and Research Centers at universities that train occupational physicians, nurses, industrial hygienists and safety engineers.

The NIOSH Hierarchy of Controls

One of NIOSH's most widely used contributions is the hierarchy of controls. As described on the NIOSH hierarchy of controls page, the five levels, ranked from generally most to least effective, are:

1. Elimination: physically remove the hazard.
2. Substitution: replace the hazard with something less dangerous.
3. Engineering controls: isolate people from the hazard through equipment or design changes.
4. Administrative controls: change the way people work, such as procedures, scheduling and training.
5. Personal protective equipment (PPE): protect the worker with equipment worn on the body.

The model appears in risk assessments, corrective action plans and management systems such as ISO 45001. When you fix the cause of an incident, the hierarchy helps you choose a durable control rather than defaulting to retraining or PPE.

Why NIOSH Matters to Employers

Even though NIOSH cannot cite you, its work affects your safety program in several practical ways:

• Filling gaps in OSHA standards. Where OSHA has no specific standard for a hazard, NIOSH recommendations are often the best available reference for what reasonable protection looks like.
• Setting protective exposure targets. RELs give you a more current benchmark when older PELs may not reflect current science.
• Choosing compliant equipment. Respirators must carry NIOSH approval to be used under OSHA's respiratory protection program.
• Supporting your risk assessments. NIOSH data, alerts and guidance help you identify hazards and justify control decisions during a risk assessment.
• Getting expert help. A Health Hazard Evaluation can bring federal scientists to examine an unusual or unexplained exposure problem at no charge.

NIOSH vs. OSHA

Confusion between the two agencies is common. Here is a clear way to separate them:

• Authority: OSHA enforces standards with inspections, citations and penalties. NIOSH has no enforcement authority.
• Department: OSHA is in the Department of Labor. NIOSH is in the Department of Health and Human Services, under the CDC.
• Output: OSHA issues legally binding regulations in Title 29 of the Code of Federal Regulations. NIOSH issues recommendations, research findings and equipment certifications.
• Exposure limits: OSHA sets enforceable PELs. NIOSH sets advisory RELs.
• Workplace visits: OSHA conducts compliance inspections. NIOSH conducts research site visits and Health Hazard Evaluations.

The two agencies are designed to work together: NIOSH produces the science, and OSHA turns some of that science into law.

How to Use NIOSH Resources in Your Safety Program

1. Check NIOSH guidance first for unfamiliar hazards. Before writing a procedure for a new chemical, process or task, search for NIOSH publications on that hazard.
2. Compare PELs and RELs. For each substance in your exposure monitoring program, record both values and decide which to use as your action level.
3. Verify respirator approvals. Confirm that every respirator in use carries a valid NIOSH approval and matches your respiratory protection program.
4. Apply the hierarchy of controls. Use it as a required step in investigations and risk assessments when selecting corrective actions.
5. Share NIOSH material with workers. NIOSH fact sheets are written in plain language and work well as toolbox talk content.
6. Consider a Health Hazard Evaluation when you face a complex exposure question your team cannot resolve internally.

Common Misconceptions About NIOSH

• "NIOSH can fine us." It cannot. NIOSH has no authority to issue citations or penalties, and a NIOSH site visit is not an OSHA inspection.
• "Meeting the OSHA PEL means exposure is safe." Not necessarily. Where a NIOSH REL is lower, it may reflect newer evidence of health effects at lower exposures.
• "Any N95 mask is NIOSH approved." Only products that have passed NIOSH testing and carry a valid approval qualify. Counterfeit and misrepresented respirators exist, so check the approval number.
• "NIOSH guidance is only for large companies." Many NIOSH resources, such as fact sheets and the hierarchy of controls, are free and practical for workplaces of any size.

How SMS360 Helps

The SMS360 Risk Assessment module helps teams document hazards, rate risks and record the controls chosen, making it easier to apply NIOSH guidance such as the hierarchy of controls consistently. Assessments can be assigned to owners, tracked to completion and reviewed on dashboards, and records are kept in one place so you can show how control decisions were made and when they were last reviewed.

Frequently Asked Questions

What is the difference between NIOSH and OSHA?

NIOSH is a research agency within the CDC that studies workplace hazards and recommends ways to prevent injury and illness. OSHA is a regulatory agency within the Department of Labor that writes and enforces legally binding safety standards. Both were created by the Occupational Safety and Health Act of 1970. NIOSH cannot issue citations or fines, while OSHA can.

Is NIOSH part of the CDC?

Yes. NIOSH is part of the Centers for Disease Control and Prevention, which is an agency of the US Department of Health and Human Services. This placement reflects its focus on occupational health research and prevention, as opposed to OSHA's enforcement role within the Department of Labor.

Are NIOSH recommended exposure limits legally enforceable?

No. NIOSH Recommended Exposure Limits are advisory. The legally enforceable limits in most US workplaces are OSHA's Permissible Exposure Limits or the limits set by a state plan. However, many employers adopt RELs as internal targets because they are often more protective and based on more recent research.

What does NIOSH approved mean on a respirator?

It means NIOSH has tested the respirator and certified that it meets federal performance requirements for its class, such as an N95 filtering facepiece. OSHA's respiratory protection standard requires employers to provide NIOSH-certified respirators. Approved products display a NIOSH approval number, which you can check against NIOSH's list of certified equipment.