What are aerosol cans, and why are they dangerous?

In short, an aerosol can is a self-contained dispensing system where a substance is stored inside a small metal canister and pushed out as a fine mist, a spray, or a foam. This mini dispensing system consists of five key elements which work together to deliver a consistent product.

Aerosols are Class 2 Dangerous Goods and must be treated with care.

Let’s look at each a little more closely.

1. Active Ingredient. This is the substance the consumer wants to use. In the workplace it is often hazardous chemicals like paint, insecticides, automotive sprays, adhesives, and solvents. But many cans also hold benign substances like cooking oil, whipped cream, and blini batter.
2. Solvent. The solvent regulates the consistency of the active ingredient — it controls the particle size and reduces the drying time. In real terms the solvent is making sure that spray paints don’t come out with lumpy bits and nasal sprays aren’t just big wet droplets. Methylal and dioxolane are solvents commonly used in aerosol cans.
3. Propellant. The propellant is the substance that pushes the active ingredient out of the can. It  usually remains in gaseous form, though it may liquefy under pressure. Aerosol food products generally use nitrous oxide or carbon dioxide as the propellant, while other substances (pharmaceuticals, paints and cosmetics) use flammable hydrocarbons.
4. Cans. Aerosol cans are leakproof and made from aluminium or steel. They protect the ingredients from contamination and evaporation as well as enabling the substances inside to be pressurised.
5. Valve. Most aerosol cans are activated by pushing a button on the top of the can which opens a valve. The valve is NOT the button, the valve itself is a set of (mostly) metal componentry consisting of (usually) a mounting cup, inner and outer gaskets, spring, valve seat, and dip tube.  

Despite the small size, each aerosol can actually contains a complex ecosystem, and this is the reason that many aerosol cans need to be shaken before you can use them.

Shaking the can mixes the active ingredient with the propellant and solvent. But it is also the combination of each of the five elements that compounds the risks and hazards of the cans. All of this stuff is going to be released if the can explodes. We’ll look at these next.

Why are Aerosol Cans Dangerous?

Aerosol cans are dangerous because of the unusual mix of substances stored under pressure inside THE metal canister. Even if the active ingredient is not a hazardous chemical (eg, food products) the can is still capable of exploding or turning into a dangerous projectile. The biggest problem with aerosol cans in the workplace is their potential to ignite or explode other Dangerous Goods and Hazardous Substances.

Here are four ways aerosol cans present a dangerous hazard in the workplace:

1. Active ingredient is a hazardous substance.

Adhesives, insecticides, automotive sprays, solvents, cleaners, paints, and varnishes are all hazardous substances and capable of causing injury if a workers inhales or absorbs the chemicals. It is so important for supervisors to check the Safety Data Sheets (SDSs) before allowing any new chemical into the workplace, sometimes this practice is forgotten when the substance arrives packaged in a neat little aerosol can.

2. Cans are overheated.

Many workplace accidents involving aerosols occur when the cans are left in the sun, in a car, or placed next to a hot machine. Two Australian workers were injured when they tried to use a can of spray paint which had been left in the sun. As one of the worker shook the can it exploded in his hand. Other workers have suffered burns and shrapnel injuries from exploding cans of cooking oil, adhesives, and electrical contact cleaner.

3. Can is ruptured or pierced.

A worker was using a can of spray paint to mark pieces of steel ready for cutting with an acetylene/oxygen cutting torch. A piece of molten metal fell onto the spray can which ruptured and the paint inside ignited. The worker was showered in burning paint and suffered terrible burns, but he was lucky the acetylene and O2 cylinders did not explode as well. Even empty cans must never be punctured or pierced as chemical residues can still present an explosion hazard.

4. Can is shaken, dropped or impacted.

A worker transferring unopened cartons of aerosol whipped cream was seriously injured when a can burst through the cardboard carton and hit him in the face. While it’s impossible to know what caused the metal canister to launch into a projectile, commercial warehouses and industrial worksites are rarely stable, temperature controlled environments. Aerosol cans (or bulk cartons) can be easily knocked over, dropped, or impacted by passing machinery and vehicles; potentially leaving the contents (active ingredients, propellant, and solvent) in a volatile state.

How to Store Aerosols Safely

The most important thing to remember about aerosol cans in the workplace is to always treat them as you would treat other Dangerous Goods. Read the Safety Data Sheets (SDS) and conduct a risk assessment before introducing them into the workplace for the first time.

Aerosol storage that meets the requirements of the Australian Standard will help keep your people, property and environment safe.

Then train your workers not to leave them lying around workbenches, inside vehicles, or near plant and machinery where they vulnerable to heat and ignition sources.

According to the AS/NZS 3833:2007 - The storage and handling of mixed classes of dangerous goods, in packages and intermediate bulk containers, aerosol cans must be:

• Protected from the weather and direct sunlight
• Stored at least 3 metres from heat and ignition sources
• Kept more than 1.5 metres from flammable liquids
• Stored in a way that prevents stacked cartons from falling over or collapsing

TIP: STOREMASTA design and manufacture a range of fully compliant aerosol cages ranging from 12 can - 432 can capacity. All are 100% Australian made by the in-house production team.

Aerosol Can Safety in the Workplace

Making sure your workplace operates legally and safely doesn’t happen by accident or chance — for more information about managing aerosols and other Dangerous Goods in the workplace why not download our free eBook Aerosol Safety and Storage. We explain your legal obligations when  handling and storing aerosol cans in clear, concise English and use plenty of real-world examples so you can relate the contents back to your own workplace. Download and read it today.