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Chemical collection and stock control for UK schools, universities and hospitals

Nitrous oxide (CAS 10024-97-2): storage and disposal

Nitrous oxide is an oxidising gas supplied in medical cylinders to dental surgeries, veterinary practices and clinics, often for sedation or anaesthetic machines. It can intensify a fire, is held under pressure and can cause drowsiness or dizziness. It is also Class C under the Misuse of Drugs Act when not for legitimate use, so a stray cylinder deserves attention. Ownership decides the route, since most cylinders return to the supplier.

CAS number
10024-97-2
Form
Gas
Storage class
Oxidiser
Signal word
Danger
Usual EWC code
16 05 04*
  • Oxidising pictogramOxidising
  • Gas under pressure pictogramGas under pressure
  • Harmful or irritant pictogramHarmful or irritant

This chemical is a manual enquiry

This is held as a compressed gas. Cylinders are usually returned to the supplier or handled separately, and they do not go into a laboratory pack.

Held as a compressed or liquefied gas in a pressure container.

It cannot be priced through a form. Please do not open or move it. Call us or send an enquiry and we will talk through the safe next step, which is often a store assessment.

What to do this week

  1. Leave it where it is. If it looks old, crystalline or damaged, do not open or move it and keep people away from the shelf.
  2. Write down the label wording, the rough age and where it is stored, from a safe distance.
  3. Send us those details, and a photo if you can take one without touching it.

Safe storage in a school or lab

Medical cylinders are the usual form, standing on a sedation unit in a dental surgery, on a veterinary anaesthetic machine or in a small store nearby. Inside, much of the contents sit as liquid under pressure, so heat is the main thing to keep away. Give spare cylinders their own labelled space, upright and secured, away from flammable, organic and reducing materials, and on non-combustible shelving if possible. As an oxidiser it can intensify a fire, so keep solvents, cardboard and cleaning rags clear, and keep oil and grease off the valve. Because it is Class C under the Misuse of Drugs Act when not for legitimate use, know how many cylinders you hold and where they are. Do not puncture or vent one.

How to tell it has deteriorated

Dust on the shoulder and an old supplier label are usually the first things you notice on a forgotten cylinder, and neither says much about the gas. Nitrous oxide gives few visible signs of age, because it does not change in a sealed cylinder. The gauge is a poor guide as well: pressure holds steady while any liquid remains and falls only near the end. Worth reporting are rust, dents, a hissing valve and frost on a valve that is not in use. The classification also covers cold burns from refrigerated gas, so keep skin away from any frosted fitting. Staff feeling drowsy or dizzy in the room can point to a leak, so move people out and tell whoever is responsible for gases.

How it must be disposed of

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

Never vent a nitrous oxide cylinder to empty it, puncture it, or put it out with clinical or general waste. Most medical cylinders belong to the gas supplier and return to them, so check the label or the hire account before anything else. A practice that has closed or changed supplier may find cylinders nobody claims. Those need a manual enquiry giving the cylinder size, the supplier markings and the location. They are not quoted online, pressure containers do not go in a lab pack, and a store assessment is recommended. Keep each one upright, secured and where it is until advice comes. Given its Class C status outside legitimate use, keep a note of what left and who took it.

Waste codes and transport details for Nitrous oxide
EWC code, laboratory chemicals16 05 04*
Hazardous wasteYes

Gases in pressure containers are assessed by manual enquiry, usually with return to the cylinder owner.

The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.

Do not store with

  • FlammableOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidMany oxidisers release toxic gas or become unstable in contact with acid.
  • AlkaliSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • ToxicToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
  • CorrosiveCorrosive stock can react with oxidisers, releasing heat or fumes.

Named chemicals to keep apart

  • Acetic acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • AcetoneOxidisers can ignite flammable materials or make a fire far more intense.
  • Ammonia solutionSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • EthanolOxidisers can ignite flammable materials or make a fire far more intense.
  • FormalinToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
  • HexaneOxidisers can ignite flammable materials or make a fire far more intense.
  • Hydrochloric acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • Mercury(II) chlorideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
Show 9 more
  • MethanolOxidisers can ignite flammable materials or make a fire far more intense.
  • Nitric acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • Potassium hydroxideSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • Sodium cyanideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
  • Sodium hydroxideSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • Sulfuric acidMany oxidisers release toxic gas or become unstable in contact with acid.
  • Thionyl chlorideCorrosive stock can react with oxidisers, releasing heat or fumes.
  • TolueneOxidisers can ignite flammable materials or make a fire far more intense.
  • Zinc chlorideCorrosive stock can react with oxidisers, releasing heat or fumes.

Common quantities we collect

Usually held as: medical cylinder.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.

Where it is commonly held

Hazard statements

  • H270 May cause or intensify fire; oxidiser.
  • H280 Contains gas under pressure; may explode if heated.
  • H281 Contains refrigerated gas; may cause cryogenic burns or injury.
  • H336 May cause drowsiness or dizziness.
Precautionary statements
  • P220 Keep away from clothing and other combustible materials.
  • P244 Keep valves and fittings free from oil and grease.
  • P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P271 Use only outdoors or in a well-ventilated area.
  • P282 Wear cold insulating gloves and either face shield or eye protection.
  • P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
  • P319 Get medical help if you feel unwell.
  • P336+P317 Thaw frosted parts with lukewarm water. Do not rub affected area. Get medical help.
  • P370+P376 In case of fire: Stop leak if safe to do so.
  • P403 Store in a well-ventilated place.
  • P403+P233 Store in a well-ventilated place. Keep container tightly closed.
  • P405 Store locked up.
  • P410+P403 Protect from sunlight. Store in a well-ventilated place.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.

Substance as classified, dilutions may differ.

Questions

The gauge on our nitrous oxide cylinder reads low. Can we count it as empty?

No. On this gas the gauge falls only late on, and a cylinder reading low can still hold gas under pressure. Return it to the supplier as a used cylinder rather than releasing what is left. Never vent it to make it lighter or easier to send back.

Can nitrous oxide sit in the same cupboard as our alcohol based disinfectants?

No. An oxidiser can make a fire far more intense, and alcohol based products are the flammable stock most surgeries have to hand. Keep those in a different store and keep cardboard stock away from the cylinders too, because that is the usual clutter around a sedation unit.

We are closing the practice and have cylinders from a supplier we no longer use. What now?

Contact that supplier first, because most cylinders are theirs and go back to them. If they cannot be traced, send a manual enquiry with the markings and location. Do not hand the cylinders to a general waste contractor, and keep them secure given the Class C position when not for legitimate use.

Does nitrous oxide go off in a cylinder that has been stored for a long time?

It does not change in any way you can see, and old stock remains an oxidiser under pressure. Condition checks therefore focus on the valve, the label and the steel body. Medical stock past its date is a matter for the supplier, and nothing should be released to run it down.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula N2O. EC number 233-032-0.

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