Your Hazardous Substances Inventory: What Has to Be In It

A list, not a folder

If you manage a workplace where hazardous substances are used, handled, manufactured or stored, you have to prepare and keep a list of them. That includes hazardous waste, which is the line most sites miss — the drum of spent solvent in the yard counts.

The point of the list is that someone can read it quickly and know what is here and how much. Fifty safety data sheets in a folder cannot do that job, because nothing in the folder tells you what is actually on site today or how much of it there is.

What each entry has to show

For every substance on the list you need:

• The name of the substance, and its UN number if it has one

• The maximum amount likely to be at the workplace

• Where it is kept

• Any specific storage and segregation requirements — either a current safety data sheet or a condensed version of the key information from it

Maximum likely, not what is there today

That third field trips people up. It is not a stocktake. It is the maximum amount likely to be on site, which means you are describing your normal operating ceiling, not Tuesday afternoon.

Get it wrong in the optimistic direction and two things follow. Emergency services plan against a number that is lower than reality, and you may fall the wrong side of a threshold you did not realise you were near.

One per site, and the fire service has to be able to read it

You need an inventory for each site you manage or control. A single group-level spreadsheet covering six branches does not satisfy six obligations.

It also has to be kept at the workplace and be readily accessible to emergency services attending during an emergency. “Readily accessible” rules out quite a lot in practice: a file on the operations manager’s laptop, a system only reachable through a login nobody on site has, a folder in the locked office whose key is with the person who has gone home.

Where location compliance certificates come in

These are a separate obligation and people routinely conflate the two. The inventory is the list. A location compliance certificate is a certification of the place, needed once you hold explosive, flammable, oxidising, toxic or corrosive substances above the regulatory thresholds.

WorkSafe gives examples such as more than 100 kg of LPG, or more than 50 litres of petrol. Published figures for flammable liquids vary depending on container size and whether they are open or closed, so check your own quantities against WorkSafe’s current guidance and calculator rather than against a number in an article — including this one.

Certificates are issued for one year for explosive, flammable and oxidising locations, and can run up to three years for toxic and corrosive ones. The certifier will want to see an inventory and a site plan showing where the substances are, which is the practical reason to have the list in order before you book the visit.

Why this is usually out of date

Almost nobody fails this requirement deliberately. The inventory gets built properly once, during a certification or an audit, and then drifts — a new product arrives, a supplier changes a formulation, a substance is quietly discontinued, and the list is updated when someone remembers.

The fix is not discipline, it is making the list the same object as the sheet. If adding a substance is what produces the inventory entry, the two cannot disagree. That is how the hazardous substances register in HazNode is built — the substance, its classification, its quantity, where it lives and its safety data sheet are one record, and the emergency inventory prints from it.