Storing and Handling Nanomaterials Safely

Read this with your safety data sheet open

This is an orientation to the published guidance and the practical failure modes. It is not a risk assessment, not a substitute for the safety data sheet supplied with your material, and not a substitute for your institution's own procedures and occupational health arrangements. Where this page and any of those disagree, they win. Where a material is pyrophoric, biologically active, or covered by a specific regulatory regime in your jurisdiction, specialist advice is required before it is opened.

With that said: much of the routine risk in a nanomaterials laboratory comes from a small number of operations, and knowing which ones they are is most of the benefit.

Why the nanoscale changes the calculation

Surface area per unit mass

A gram of nanopowder can present tens or hundreds of square metres of surface. Reactivity, dissolution rate, catalytic activity and biological interaction all scale with accessible surface rather than mass, which is why a material that is inert in bulk can be anything but as a nanopowder. The BET guide covers how that area is measured; here it matters because it is the reason the bulk safety data sheet may not describe the material in front of you.

Where inhaled particles go

Deposition in the respiratory tract depends on aerodynamic behaviour, and nanoscale particles behave differently from the respirable dust that most occupational hygiene practice was built around: a substantial fraction of ultrafine particles that are inhaled deposit in the deep lung, and diffusion rather than impaction governs where they land. Airborne nanoparticles also agglomerate rapidly, so what is inhaled is often an agglomerate rather than a primary particle — which is a real complication in exposure assessment, not a reassurance.

Mass is the wrong metric

Conventional exposure limits are expressed as mass per cubic metre. For nanomaterials, a mass-based limit can be met comfortably while the particle-number and surface-area concentrations are very high, because the mass of a nanoparticle is tiny. This is why nanomaterial-specific recommended limits exist and are numerically far below the corresponding bulk values, and why exposure assessment for nanomaterials increasingly uses number and surface-area metrics alongside mass.

Two concrete examples from the published guidance. The US National Institute for Occupational Safety and Health, in Current Intelligence Bulletin 63, recommends exposure limits for titanium dioxide that are an order of magnitude lower for ultrafine material than for fine — 0.3 mg/m³ against 2.4 mg/m³, as time-weighted average concentrations. In Current Intelligence Bulletin 65, NIOSH recommends an exposure limit for carbon nanotubes and nanofibres of 1 microgram per cubic metre of elemental carbon, as an eight-hour time-weighted average respirable mass concentration — a limit low enough that measuring compliance requires specific analytical methods rather than a general dust monitor. NIOSH has since published bulletins covering other nanomaterials, including silver, with their own recommended limits.

Those are recommendations from one national body, not universal legal limits, and the regulatory position differs by jurisdiction. Check what applies where you are. The point of quoting them here is the magnitude: they are far below general dust limits, and a control strategy designed for ordinary powders is not automatically adequate.

The operations that carry the risk

Exposure in practice is dominated by a handful of steps, and the highest-risk material state is dry, unbound powder:

• Weighing and decanting dry powder. The single riskiest routine operation. Low-density nanopowders aerosolise from the smallest disturbance, hold electrostatic charge, and cling to spatulas and vessel walls.
• Opening a container that has been shaken in transit. The headspace may already hold an aerosol before you touch anything.
• Harvesting product from a reactor, furnace or filter. Frequently the largest quantity of dry material anyone handles.
• Sonicating or high-shear mixing a suspension. Generates aerosol and droplets from a liquid that felt safe. Probe sonication is worse than bath sonication.
• Spray drying, electrospinning, thermal spraying and any other process that deliberately produces an aerosol.
• Cleaning up. Dry sweeping and compressed-air blow-down re-suspend everything that has settled and are the classic way to turn a contained incident into a dispersed one.
• Machining or abrading a nanocomposite, which can release matrix fragments with nanomaterial attached, or free nanomaterial, or both.

Working with the material already in suspension, in a gel, or bound in a matrix substantially reduces inhalation risk. Where a process can be redesigned to keep the material wet, that is a control measure and usually a cheap one.

Controls, in the order that works

The conventional hierarchy applies unchanged: eliminate, substitute, engineer, administer, and only then personal protective equipment. Applied to nanomaterials:

Elimination and substitution

Buy the material as a dispersion, a paste or a masterbatch rather than a dry powder where the application allows. Order the quantity actually needed rather than the economical larger pack that then has to be repeatedly decanted. Work at the smallest scale that answers the question.

Engineering controls

• Ducted fume hood. Adequate for many wet operations. For dry powders, face velocity that is too high can pull powder out of an open vessel, and a conventional hood is not designed for that.
• Powder-handling or balance enclosure with HEPA filtration. The appropriate control for weighing and decanting dry nanopowder — low turbulence, filtered exhaust, contained.
• Glovebox or fully enclosed system. The right answer for pyrophoric, air-sensitive or highly hazardous material, and for larger quantities.
• Biological safety cabinet. Only where the class is appropriate and the exhaust is HEPA filtered; a recirculating cabinet not intended for particulates is not a control.
• Local exhaust ventilation at the point of release for reactor harvesting and machining operations.

Whatever is used, it needs verification: face velocity or containment testing on a schedule, HEPA filters specified for the duty, and a documented procedure for changing them, because a loaded filter is concentrated waste.

Administrative controls

A designated area with defined boundaries and controlled access. Written procedures for the high-risk operations above. Restricting dry-powder work to times when few people are present. Smooth, non-porous, cleanable surfaces with no carpet and no clutter. Wet wiping or HEPA vacuuming rather than sweeping. No food, drink or storage of personal items in the area. Training that covers why the controls exist, because a control whose purpose is not understood is a control that gets bypassed.

Personal protective equipment, and what it cannot do

PPE is the last line and the least reliable, because it protects one person, only while worn correctly, and fails silently.

• Gloves. Nitrile is the usual baseline; double gloving is common practice for dry powder work. Chemical compatibility is governed by the solvent, not by the nanomaterial. Change them often, and remove them before touching door handles, keyboards or telephones — tracked contamination is a genuinely common route out of a controlled area.
• Body protection. Non-woven laboratory coats or coveralls shed and retain less than woven cotton. Keep them in the area; do not take them home.
• Eye protection appropriate to the task, and to the solvents, not to the particles alone.
• Respiratory protection. Effective filtering respirators exist and filtration efficiency at nanoscale particle sizes is generally good — filters do not have a hole through which nanoparticles simply pass. The weak point is fit. A respirator is only meaningful within a formal respiratory protection programme with fit testing, medical clearance, training and maintenance. Handing someone a mask from a drawer is documentation, not protection. Treat respirators as a supplement to engineering controls, or as cover for maintenance and spill response, not as a routine substitute.

Storage

Dry powders

Sealed primary container inside closed secondary containment, so that a failure of the first is caught by the second. Store the smallest working quantity in the laboratory and the bulk elsewhere. Keep containers upright and undisturbed — repeated handling is what generates aerosol, so a container that is opened once a week is a bigger source than one opened once a month. Static charge is a real nuisance with light powders; conductive containers and grounded equipment help. Control humidity: many nanopowders are hygroscopic, and absorbed water changes both the mass basis of your weighing and the dispersion behaviour.

Air-sensitive and pyrophoric material

Some metal nanopowders — including several of the reactive base metals — are pyrophoric at nanoscale even where the bulk metal is not, because the surface area available for oxidation is so much larger. These are supplied either passivated with a controlled surface oxide or under inert atmosphere or solvent, and the supplier's instruction on which is not optional. Handle under inert gas, never allow a dry sample to dry further in air, and treat any material that warms on exposure as a fire, not a spill.

Suspensions and dispersions

A dispersion is not a solution and does not keep indefinitely. Expect settling, agglomeration and ripening over time. Storage temperature matters and freezing is often destructive — the growing ice front concentrates particles and forces them together, and many dispersions never recover from a freeze-thaw cycle. Note the dispersant: an aqueous suspension with a surfactant can support microbial growth. Redispersion before use should follow a defined protocol — a stated sonication time and power, not "until it looks fine" — because dispersion state is part of the material specification and a variable dispersion protocol makes the whole downstream experiment irreproducible. Confirm with a sizing measurement rather than by eye, and keep an eye on zeta potential if stability is marginal.

Photosensitive and oxidation-sensitive material

Quantum dots, many organic-functionalised particles and some metal colloids degrade under light and oxygen. Amber glass or foil, headspace purged with inert gas, and cold storage where the supplier specifies it. Record the date opened, not only the date received.

Labelling and inventory

Every container should carry the material, the form, the lot number, the date received, the date opened, the hazard information, and the location of the safety data sheet. An inventory that records how much is where is the difference between a manageable incident and an unbounded one, and it is also what makes the retest dates on a certificate of analysis actionable — see how to read a certificate of analysis.

Spills, decontamination and disposal

Wet methods first. For a dry spill, dampen rather than sweep, or use a HEPA-filtered vacuum specified for the duty — a workshop vacuum without HEPA filtration is a device for aerosolising a spill efficiently. Wipe with damp disposable cloths, working from the outside inward. Treat wipes, gloves, filters and disposable coveralls as contaminated waste.

Waste routes are jurisdictional and must be confirmed with your environmental health and safety office. What is general: nanomaterial waste should not go to ordinary laboratory glass or paper streams, liquid waste containing nanoparticles should not go down the drain, spent HEPA filters are concentrated waste and should be bagged in place, and the waste label should say what the material is rather than "nanoparticles".

Shipping

Transport classification follows the substance's hazard properties under the applicable dangerous-goods regulations, and there is no general "nanomaterial" transport class. What this means in practice is that a pyrophoric metal nanopowder, a flammable solvent dispersion and an inert oxide powder are three different shipping problems, and the classification must be determined for the material as supplied — including the solvent, which is frequently the regulated component. Suppliers should provide the classification, the UN number where one applies, and the correct documentation; ask before ordering if you are importing something unfamiliar, because a consignment stopped at a border is a slow and expensive way to discover this.

The published guidance to read

• NIOSH, "Approaches to Safe Nanotechnology" — the practical control-oriented handbook, and the most useful single starting point.
• NIOSH Current Intelligence Bulletin 63 (titanium dioxide) and 65 (carbon nanotubes and nanofibres) — the derivations behind the recommended limits quoted above, and worth reading for the reasoning as much as the numbers.
• ISO/TR 12885 — health and safety practices in occupational settings relevant to nanotechnologies.
• ISO/TS 12901-1 and -2 — occupational risk management applied to engineered nanomaterials, including the control-banding approach, which is the practical method when toxicological data are absent.
• The OECD Working Party on Manufactured Nanomaterials publication series, for the underlying testing and assessment work.
• Your material's safety data sheet, read with the knowledge that it may describe the bulk substance rather than the nanoform.

Why this marketplace declares hazard handling

How nanoMani works commits to hazard information being declared as a field on a listing rather than left to the description. The reason is everything above: the storage condition, the pyrophoricity, the solvent and the shipping classification are properties of the material that determine whether a buyer can accept it at all, and a listing that omits them has left the most consequential question to a follow-up email.

Related guides

• The measurements behind the specification: the characterisation workflow.
• What should have arrived with the material: how to read a certificate of analysis.
• Surface area, which is the reason nanoscale reactivity is what it is: BET surface area analysis.