Prevention through

Design (PtD)

Prevention through Design (PtD) 

can be defined as designing out 

or eliminating safety and health 

hazards associated with processes, 

structures, equipment, tools, or 

work organization. The National 

Institute for Occupational Safety 

and Health (NIOSH) launched a 

PtD initiative in 2007. The mission 

is to reduce or prevent occupational 

injuries, illnesses, and fatalities by 

considering hazard prevention in 

the design, re-design, and retrofit of 

new and existing workplaces, tools, 

equipment, and work processes 

[NIOSH 2008a,b]. 

Protecting Workers during the 

Handling of Nanomaterials

Summary 

Engineered nanomaterials (ENMs) 

are materials that are intentionally 

produced to have at least one primary 

dimension less than 100 nanometers (nm). These materials have new 

or unique properties different from 

those of larger forms of the same 

material, making them desirable for 

specific product applications. The 

health effects associated with nanomaterials are not yet clearly understood, 

so it is important for producers and 

users of ENMs to reduce employee 

exposure and manage risks appropriately.  In 2013, the National Institute 

for Occupational Safety and Health 

(NIOSH) published a compendium of 

control approaches for nanomaterial 

production and use processes entitled 

Current Strategies for Engineering Controls in Nanomaterial Production and 

Downstream Handling Processes. This 

Workplace Design Solutions document provides guidance on exposure 

control options for protecting workers 

during the handling of nanomaterials.

Background 

The toxicity of many nanomaterials is 

presently unknown, but initial research 

indicates that there may be health 

concerns related to occupational inhalation exposures. Only a few types of 

ENMs have undergone extensive toxicological evaluation by NIOSH, e.g., 

titanium dioxide (TiO2

) and carbon 

nanotubes (CNTs). Results from animal studies with TiO2

 and other poorly-soluble, low-toxicity particles of fine 

and ultrafine (nanoscale) sizes have 

shown adverse pulmonary responses 

in exposed rats, including persistent 

pulmonary inflammation and lung tumors [NIOSH 2011; Oberdörster 2002; 

Donaldson 2009; Poland et al. 2012]. 

Similar toxicological responses have 

also been observed in rats and mice 

exposed to CNTs and carbon nanofibers (CNFs) [NIOSH 2013a]. Because 

of the potential for adverse human 

health effects, it is important to control 

worker exposure and to manage risks 

appropriately throughout the lifecycle 

of ENM production.

Description of 

Exposure

Small-scale handling of nanopowders 

is a common task; examples include 

working with a quality assurance/control sample, weighing out a specific 

quantity for mixing/compounding, 

and processing smaller quantities in 

downstream industries. The tasks 

Centers for Disease Control

and Prevention

National Institute for Occupational 

Safety and Health
of weighing out nanomaterials can lead to worker exposure 

primarily through the scooping, pouring, and dumping of these 

materials. Dahm et al. [2012] conducted exposure assessments 

at six manufacturers and users of carbon nanotubes and nanofibers.  This study showed that the highest exposures occurred 

during dry powder handling tasks including mixing and weighing operations.  Many different types of commercially available 

enclosures can be employed to reduce exposure during the 

handling of nanopowders. The controls described below include chemical fume hoods, nanomaterial handling enclosures, 

biological safety cabinets [BSCs], and glovebox/isolators.  This 

document provides information about hood and laboratory design and operation, administrative controls (such as good work 

practices), and the use of personal protective equipment. 

NIOSH recommends that manufacturers and downstream users of nanomaterials develop PtD strategies to protect workers 

during the handling of engineered nanomaterials. Engineering 

controls protect workers by removing hazardous conditions 

or placing a barrier between the worker and the hazard, and 

along with good material handling techniques, they are likely 

to be the most effective control strategy for nanomaterials. The 

identification and adoption of effective control technologies 

is an important first step in reducing the risk associated with 

worker exposure to ENMs and ENM-associated byproducts. 

Engineering Controls 

A primary engineering control used in the nanotechnology 

industry during the handling, weighing, mixing, or sonication of engineered nanomaterials is a ventilated enclosure. 

These enclosures include fume hoods, nanomaterial handling 

enclosures, glove box/isolators, and biological safety cabinets 

(BSC) [NIOSH 2013b]. In addition, Bag In/Bag Out filter 

change out systems can help protect workers when removing 

filters contaminated with nanomaterials. Each of these controls 

should be carefully designed and properly operated to be effective. Many of the recommendations below have been compiled 

from documents by NIOSH and professional organizations 

[ANSI/AIHA 2012; NIOSH 2012, 2013b; NRC 2011].

Design and Operational Considerations

The following should be considered during the design and 

installation process for ventilated enclosures, such as fume 

hoods, nanomaterial handling enclosures and BSCs.

 Consult a qualified industrial ventilation engineer, 

industrial hygienist, or containment specialist to design the 

new control system.

 Locate the ventilated enclosure away from doors, aisles, 

walkways, and room air supply registers. Locate the hood 

a minimum of 5 feet from any HVAC air supply grille; a 

distance of 10 feet is preferred [NIOSH 2012]. 

 Avoid air currents that are 30%–50% of the hood face 

velocity (typically between 30–50 feet per minute [fpm]) as 

these tend to reduce containment efficiency [NRC 2011]. 

Check for an air face velocity between 80 and 100 fpm into the 

chemical fume hood. For higher toxicity materials, a higher 

face velocity (between 100–120 fpm) may provide better 

protection. However, face velocities exceeding 150 fpm may 

not improve performance and may increase hood leakage. 

 Newer nanomaterial handling enclosures may provide 

adequate containment at lower face velocities [NRC 

2011]. These hoods are often based on ventilated 

balance enclosures used for potent powder handling in 

pharmaceutical applications and typically operate at an 

average face velocity between 65–85 fpm.

 Ensure that each enclosure has an airflow indicator to 

show that it is working properly. This may include a flow 

indicator, flow alarm, or face velocity alarm that alerts users 

to improper exhaust flow.

 Keep exhaust ducts short and simple—avoid flexible duct 

if possible. The duct material and filters chosen need to be 

compatible with the ENMs and byproducts generated.

 Consider using Bag In/Bag Out filter change out systems to 

reduce the risk of exposure to maintenance personnel. 

 Ensure good lighting so workers are able to see well and 

possibly notice dust escaping.

 Conduct initial performance tests of the control as installed 

at the facility. Use tracer gas tests described in consensus 

standards to evaluate containment effectiveness [ASHRAE 

1995]. These tests should be scheduled as part of a regular 

preventive maintenance program to ensure adequate 

containment.

 Use of nanopowders that are pre-mixed in a liquid may 

reduce the potential for airborne exposure if they are 

compatible with the process.

 Restrict access to only those workers required to be in the 

work area.

 Post appropriate warnings, including how to protect 

workers and visitors from exposure risks. 

Preventive Maintenance and 

System Checks

 Develop a written preventive maintenance (PM) plan to check 

system performance and repair identified deficiencies.

 Keep equipment in effective and efficient working order. Review 

the enclosure manufacturer’s performance specification to know 

whether the control is working properly. 
 Look for signs of damage to the ducting and enclosure. 

Repair damage immediately.

 Regularly check that the enclosure system and the 

airflow indicator work properly and that the enclosure 

has no visible dust leaks.

 Have a qualified industrial ventilation engineer or 

industrial hygienist examine the ventilated enclosure 

system and check its performance at least once every year 

or if it is modified or relocated.

 At least annually, measure hood face velocity using 

procedures such as those detailed by consensus 

organizations (ACGIH, ASHRAE, ANSI), check airflows 

using smoke tracers, and verify the accuracy of installed 

flow monitoring devices such as face velocity monitors 

[ACGIH 2016; ANSI/AIHA 2012; ASHRAE 2011]. Keep 

this information in a PM logbook.

 Conduct routine industrial hygiene monitoring to ensure 

controls are working at design conditions. 

The figures below show the different engineering controls and what 

should be known about each as well as the limitations of their use.

Chemical Fume Hood 

▶ Common control used in many settings, including 

with nanomaterials.

▶ Effectively contains nanomaterials for a range 

of activities.

▶ Should include design features such as airfoils 

at all edges and baffles inside the unit to reduce 

turbulence and improve containment. 

▶ Older versions with constant airflow were 

found to leak even at the design face velocity 

[Tsai et al. 2009].

▶ Exhausts directly out of facility—not recirculated 

into workplace.

▶ Larger size, higher and potentially disruptive 

airflows compared with the nanomaterial 

handling enclosure.

▶ Higher energy costs for both fan motor and 

tempered replacement air than for low flow units 

such as the nanomaterial handling enclosure.
Nanomaterial Handling Enclosure 

▶ Similar to pharmaceutical ventilated balance enclosures.

▶ Molded airfoils at edges, sill, and sash reduce turbulence.

▶ Some enclosures recirculate HEPA-filtered exhaust 

flows back into lab.

— Recirculating hoods are not appropriate for work 

with hazardous chemicals, such as solvents, which 

are not removed by HEPA filters. 

▶ Consider using units with improved features such 

as Bag In/Bag Out exhaust filters and waste disposal 

chutes for better containment.

▶ Generally smaller and lower flow than chemical 

fume hoods.

— Provide improved environment for weighing/

handling nanomaterials.

— Protection may be compromised by airflow 

disturbances due to poor lab design/layout.

— Reduced energy usage due to lower airflow.

Glovebox/Isolator

▶ Highest level of protection for working with nanomaterials 

or other hazardous chemicals. Guidance on design, testing, 

and maintenance of these units is available [AGS 2007].

▶ Gloveboxes should be maintained at negative pressure so 

leaks are into the box rather than out of the box. 

▶ These devices may be awkward to use due to restricted 

arm movements and difficulty seeing the process clearly. 

Consider using a mockup to assess ergonomic design prior 

to purchase.

▶ Conduct tests to verify that unit is operating as designed. 

Units require periodic inspection to check for tears in 

gloves and leaks.

▶ Energy costs are generally lower than other controls 

discussed here since very little exhaust flow is required to 

maintain negative pressure.
Biological Safety Cabinet (BSC)

▶ Primary use is working with biological aerosols.

▶ There are several different types of BSCs, so care must be 

taken to understand the suitability of the hood for providing 

personnel protection when handling nanomaterials.

▶ The most common BSC, a Class II hood, protects both 

worker and product by containing the work while providing 

clean air to work surface.

▶ BSCs may recirculate HEPA-filtered air to work room and/or 

exhaust directly to outside.

— Recirculating hoods are not appropriate for work with 

hazardous chemicals, such as solvents, which are not 

removed by HEPA filters.

— Canopy connections (BSC Class II Type A2) are 

preferred for BSCs that exhaust to the outside.

▶ The downward air flow toward the work surface may 

make BSCs problematic when working with powdered 

nanomaterials.

Bag In/Bag Out Filter

Change Out

▶ Allows for removal of a dirty air filter while 

minimizing worker exposure.

▶ The containment bags often have integral gloves 

to make removing filter easier.

▶ A filter containment bag is attached to a service 

port on the unit by a safety strap.

▶ Bags with contaminated filters are cinched, 

closed using a double crimp/cut procedure, and 

disposed of properly.

▶ This process contains the filter with its 

contaminants so the worker is not exposed, 

and the particulates are not resuspended in the 

workplace environment.
Administrative Controls 

The use of engineering controls is likely the most effective 

control strategy for exposure to nanomaterials. Administrative 

controls and personal protective equipment (PPE) also have a 

place in PtD strategies and are usually identified as additional 

safeguards. Work practices, an administrative control, are procedures followed by employers and workers to control hazards 

in the workplace. These include housekeeping and cleaning, 

storage and use procedures, labels and postings, hazard training, and procedures for the use of engineering controls, many 

of which are discussed below. In addition, respirators may 

be needed and are often used during the implementation of 

engineering controls and work practices as well as during some 

short-duration maintenance procedures, and in emergencies. 

Therefore, facilities should consider the following administrative and PPE approaches as a part of a comprehensive occupational safety and health management plan for nanomaterial 

production and use.

Good work practices

 For laboratory fume hood use, ensure that the sash is set at 

the certification mark for proper hood face velocity. Ensure 

that the sash is lowered and between the worker and the 

nanomaterial.

 Avoid opening and closing the sash quickly and minimize 

rapid arm movements to reduce material leakage. 

 Place materials and equipment as far back in the hood as 

practical (at least six inches) without blocking the back 

slots/baffles. Mark the work surface six inches from the 

hood face to reinforce good work practices. 

 For chemical fume hood use, do not overcrowd or block 

the exhaust slots in the back of the hood. Place larger 

objects and equipment on blocks or racks to allow airflow 

to more smoothly reach the exhaust section of the hood.

 When possible, work with the nanomaterials at the center 

of the hood for best containment efficiency. Visual tools 

such as tracer smoke or dry ice in a small container of water 

can help verify good capture within the enclosure.

 Keep all unnecessary equipment and glassware out of the 

hood and appropriately stored. 

 Clean work surfaces with appropriate techniques (wet 

wipes or HEPA vacuum) as needed throughout the day and 

at least at the end of each day or work shift. 

 Clean up spills of liquids containing nanomaterials using 

absorbent materials and dispose of cleaning materials and 

waste in accordance with hazardous waste procedures. 

Cleaning and Housekeeping

 Clean the work area and equipment every day. Deal with 

spills immediately according to written procedures and 

using appropriate PPE. Standard approaches for cleaning 

spills can be used for cleaning surfaces contaminated with 

dry powder nanomaterials. These include using HEPAfiltered vacuum cleaners, wiping up dry powders with 

damp cloths, or wetting the powder before wiping.

 Dispose of cleaning wipes and other contaminated materials 

in a sealed bag to prevent release of the dried nanomaterial. 

Nanomaterial-contaminated waste, including cleaning 

materials, should be kept in a separate waste stream.

 Do not use dry methods such as a brush, broom, or 

compressed air to clean up contaminated work surfaces.

 Cover all containers when not in use. Dispose of empty 

containers safely.

Training

 Provide safety and health training to workers, supervisors, 

and managers including information on proper use, 

maintenance, and inspection of the control.

 Provide workers with sufficient information to allow them 

to understand the nature of potential workplace exposures, 

health risks, routes of exposure, and instructions for 

reporting health symptoms [OSHA 2012].

 Ensure that training includes how to keep exposures low; 

how to check that the ventilated enclosure is working; how 

to use and care for PPE, including respirators; and what to 

do if something goes wrong.

Personal Protective Equipment

Personal Protective Clothing

Because some types of nanoparticles have been found to penetrate the skin, appropriate protective clothing should be worn. 

PPE should be required when engineering and/or administrative controls are not feasible or effective in reducing exposures or 

when controls are not feasible such as maintenance or response to 

a spill. Follow job hazard assessment procedures for determining 

the need for and selection of PPE [OSHA 2002; ACS 2015]. 

 If appropriate, use nitrile or other chemically impervious 

gloves during handling and cleanup of nanomaterials. 

Gloves should be selected based on their effectiveness 

against the nanomaterial as well as any other chemicals 

being used. Gloves should be inspected before use and 

changed at least at the end of each shift and whenever they 

show visible signs of wear. Used gloves should be kept 
in a sealed plastic bag in the work area until they can be 

disposed of properly.

 Never use compressed air or other high energy techniques 

such as brushing or shaking to remove dust from clothing. 

Respirators

Employers should consult with an occupational safety and health 

professional to determine the respirator best suited for their 

specific application. Employers should always follow the Occupational Safety and Health Administration (OSHA) Respiratory 

Protection Standard (29 CFR 1910.134) if respiratory protection is 

used (www.osha.gov/SLTC/etools/respiratory/index.html). NIOSH 

guidance for selecting respirators is found at http://www.cdc.gov/

niosh/docs/2005-100/default.html [NIOSH 2004]. 

Acknowledgments

This document was prepared by Dr. Kevin H. Dunn, Ms. Jennifer 

Topmiller, and Ms. Trudi McCleery, NIOSH Division of Applied 

Research and Technology, and Mr. John J. Whalen, formerly with 

NIOSH. Mr. Eugene Smith (on contract with NIOSH) prepared 

the illustrations. The authors gratefully acknowledge the contributions of the following NIOSH personnel who assisted with 

the technical content and review of the document, including: 

Ms. Laura Hodson, Dr. Pengfei Gao, Mr. Kevin L. Dunn, and Dr. 

Mark Hoover. Special appreciation is expressed to the following 

who served as external peer and stakeholder reviewers, including 

Dr. Kwangseog Ahn, Ms. Theresa Lane, Ms. Pamela Greenley, and 

Mr. Gary Partington.

Suggested Citation

NIOSH [2018]. Protecting workers during the handling of 

nanomaterials. By Dunn KH, Topmiller JL, McCleery T, Whalen J. Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and H ealth, DHHS (NIOSH) 

Publication No. 2018-121. DOI: https://doi.org/10.26616/

NIOSHPUB2018121

References

ACGIH [2016]. Industrial ventilation: a manual of recommended practice for design. 29th Ed. Cincinnati, OH: American 

Conference of Governmental Industrial Hygienists.

ACS [2015]. Identifying and evaluating hazards in research 

laboratories. Washington, DC: America Chemical Society. 

https://www.acs.org/content/dam/acsorg/about/governance/

committees/chemicalsafety/publications/identifying-and-evaluating-hazards-in-research-laboratories.pdf

AGS [2007]. Guideline for gloveboxes, 3rd Edition. AGS-G001. 

Santa Rosa, CA: American Glovebox Society. 

ANSI/AIHA [2012]. American National Standard for laboratory ventilation. Fairfax, VA: American Industrial Hygiene 

Association Publication No. ANSI Z9.5–2012.

ASHRAE [1995]. Method of testing performance of laboratory 

fume hoods. American Society of Heating, Refrigerating, 

and Air Conditioning Engineers.

Dahm MM, Evans DE, Schubauer-Berigan MK, Birch ME, 

Fernback JE [2012]. Occupational exposure assessment in 

carbon nanotube and nanofiber primary and secondary 

manufacturers. Ann Occup Hyg 56:542–556.

Donaldson K [2009]. The inhalation toxicology of p-aramid 

fibrils. Crit Rev Toxicol 39:487–500.

NIOSH [2004]. NIOSH respirator selection logic. Cincinnati, OH: 

U.S. Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 

2005-100. https://www.cdc.gov/niosh/docs/2005-100/default.html

NIOSH [2008a]. Prevention through design: introduction. By 

Howard J. J Safety Res 39:113. http://www.cdc.gov/niosh/topics/ptd/pdfs/Howard.pdf

NIOSH [2008b]. National prevention through design (PtD) 

initiative. By Schulte P, Rinehart R, Okun A, Geraci C, Heidel D. 

http://www.cdc.gov/niosh/topics/ptd/pdfs/Schulte.pdf

NIOSH [2011]. Current intelligence bulletin 63: occupational 

exposure to titanium dioxide. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease 

Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 2011-

160. http://www.cdc.gov/niosh/docs/2011-160/

NIOSH [2012]. General safe practices for working with engineered nanomaterials in research laboratories. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, DHHS (NIOSH) Publication 

No. 2012-147. http://www.cdc.gov/niosh/docs/2012-147/

NIOSH [2013a]. Current intelligence bulletin 65: occupational exposure to carbon nanotubes and nanofibers. 

Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS 

(NIOSH) Publication No. 2013-145. http://www.cdc.gov/

niosh/docs/2013-145/

NIOSH [2013b]. Current strategies for engineering controls in 

nanomaterial production and downstream handling processes. By Topmiller JL, Dunn KH. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease 

Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 2014-

102. http://www.cdc.gov/niosh/docs/2014-102/ 
NRC [2011]. Prudent practices in the laboratory: handling 

and management of chemical hazards, updated version. 

Washington, DC: The National Academic Press, National 

Research Council. 

Oberdörster G [2002]. Toxicokinetics and effects of fibrous and 

nonfibrous particles. Inhal Toxicol 14:29–56.

OSHA [2002]. Job hazard analysis. Washington, DC: U.S. 

Department of Labor, Occupational Safety and Health 

Administration. Publication No. 3071 (Revised). https://

www.osha.gov/Publications/osha3071.pdf

OSHA [2012]. Hazard Communication (29 CFR 

1910.1200). https://www.osha.gov/pls/oshaweb/owadisp. 

showdocument?p_table=standards&p_id=10099.

Poland CA, Byrne F, Cho W, Prna-Mello A, Murphy FA, 

Davies GL, Coey J, Gounko Y, Duffin R, Volkov Y [2012]. 

Length-dependent pathogenic effects of nickel nanowires in 

the lungs and the peritoneal cavity. Nanotoxicol 6:899–911.

Tsai SJ, Ada E, Issacs JA, Ellenbecker MJ [2009]. Airborne nanoparticle exposures associated with the manual handling of nanoalumina and nanosilver in fume hoods J Nanopart Res 11:147–161.

For More Information

NIOSH developed detailed information about comprehensive PtD strategies for nanomaterial use and production [NIOSH 2013b] that can be found in the document 

Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes (http://

www.cdc.gov/niosh/docs/2014-102/pdfs/2014-102.pdf). 

The information in this document is based on research related to Prevention through Design (PtD) initiatives. More 

information about PtD is available on the NIOSH website 

at http://www.cdc.gov/niosh/topics/PtD/

The Nanotechnology Research Center (NTRC) leads the 

federal government nanotechnology initiative to conduct 

research and provide guidance on the occupational safety 

and health implications and applications of nanotechnology. More information about the NTRC is available on 

the NIOSH website at https://www.cdc.gov/niosh/topics/

nanotech/nanotechnology-research-center.html

Engineering controls protect workers by removing hazardous conditions or by placing a barrier between the worker 

and the hazard. More information about the Engineering 

Controls Program is available on the NIOSH website at 

https://www.cdc.gov/niosh/engcontrols/

To obtain information about other occupational safety and 

health topics, contact NIOSH at:

Telephone: 1–800–CDC–INFO (1–800–232–4636)

TTY: 1–888–232–6348 • CDC INFO: www.cdc.gov/info

or visit the NIOSH website at www.cdc.gov/niosh

For a monthly update on news at NIOSH, subscribe to 

NIOSH eNews by visiting www.cdc.gov/niosh/eNews. 

Mention of any company or product does not constitute 

endorsement by NIOSH. In addition, citations to websites 

external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or their programs or 

products. Furthermore, NIOSH is not responsible for the 

content of these websites.

This document is in the public domain and may be freely 

copied or reprinted. NIOSH encourages all readers of the 

Workplace Design Solutions to make them available to all 

interested employers and workers.

As part of the Centers for Disease Control and Prevention, 

NIOSH is the Federal agency responsible for conducting 

research and making recommendations to prevent workrelated illness and injuries.

March 2018 Publication No. 2018-121 DOI: https://doi.org/10.26616/NIOSHPUB2018121