# OH₂S: Hazardous substances and their storage

URL: https://bhp-panic.pl/en/blog/how-hazardous-substances-act-and-how-to-store-them
Published: 2026-10-29
Author: Konrad Hyra
Language: en
Site: BHP Panic (bhp-panic.pl)

In the previous article we covered the basic hazards posed by chemical substances; we already know the routes of absorption and how hazardous substances are labelled. Now let us look at exactly how they act, and what conditions a warehouse must meet to store them safely.

## Toxic substances

As an example, take a worker at a galvanising plant, a steelworks or a battery recycling facility. This group of workers is exposed to lead, a highly toxic heavy metal that is easily carried by the bloodstream and therefore accumulates in the cells of organs such as the kidneys, brain and bones. Once it gets there, it can damage cells and disrupt their function, among other reasons because it displaces ions the body needs, such as calcium or zinc. Sounds frightening, doesn't it? With toxins it is especially important to prevent ingestion (through the digestive tract) and inhalation (through the respiratory tract).

The main mechanism by which toxins act on the human body is damage to cellular structures, disruption of enzyme function, and blocking or stimulating receptors. A toxin can therefore interfere with specific processes inside a cell or with communication between cells.

## Flammable substances

Flammable substances are materials capable of burning under the right conditions, that is, in the presence of an oxidiser and an ignition source, or once conditions that allow self-ignition are reached. Combustion is a chemical reaction that is usually accompanied by the release of heat and often light as well. The term “highly flammable” indicates a greater susceptibility of a substance to ignition. In practice, this means that relatively small stimuli, such as a spark, may be enough to ignite it.

A typical combustion process requires three elements (the so-called fire triangle): a combustible material, an oxidiser and an ignition source. Under normal conditions the role of the oxidiser is most often played by oxygen from the air. Some chemicals, however, can intensify combustion or enable violent reactions even where access to oxygen from the surroundings is limited.

## Safe storage, or which substances not to combine.

When planning the storage of the substances used in a plant, we should think about conditions such as temperature, sunlight and humidity. Some substances become dangerous once the boundary conditions of storage are exceeded. There are also those that become dangerous in the presence of another substance with which, for example, they react strongly. That is why, when setting storage rules, we must remember to avoid such combinations. In the following sections we will look at the most commonly described dangerous combinations.

## Acids and bases: the risk of a violent exothermic reaction.

You may have heard of a kitchen life hack for getting rid of burnt-on residue in a frying pan. First you sprinkle the burnt spot with baking soda (sodium bicarbonate), then you drizzle it with lemon juice. The effect is immediate: the mixture starts to foam and spatter slightly, and the burnt material is eaten away. You can remove it with a single swipe of a scourer. Even on this small, domestic scale, an acid and a base make for a rather spectacular process.

An acid-base reaction in chemistry is a process in which salts are formed as a result of mutual neutralisation between an acid and a base. “Neutralisation” may sound mild, yet the reaction can be very violent and release a large amount of energy in the form of heat. As a result, such a mixture of substances heats up strongly, and may even start to boil and spatter corrosive liquid.

### How do I know what is an acid and what is a base?

Under the pictogram on the label you will find the signal word: “Danger” or “Warning”. Look for key words in the description. Acids have the word “acid” in their name, e.g. sulphuric acid, hydrochloric acid, acetic acid. Substances with a basic (alkaline) reaction often have the word hydroxide in their name, or in household chemicals a name such as “soda base” or “caustic soda”, e.g. sodium hydroxide, soda base, caustic soda. If in doubt, it is best to check online whether a given substance is a base before deciding to store it next to an acid.

## Oxidisers and combustible materials: the risk of fire or a violent reaction.

The fire triangle is a concept worth understanding when we think about fire protection. It describes three elements that together cause a fire: a material that can burn, an oxidiser that strengthens the combustion reaction, and an ignition source. By storing oxidisers and combustible materials together, we leave only the last element missing, and even a single spark may be enough to start a fire.

The group of oxidising substances includes, among others, hydrogen peroxide, ammonium nitrate and nitric acid. Combustible materials can be in different states of matter: solid (such as polyethylene), liquid (e.g. acetone) or gas (e.g. hydrogen). Many oxidisers are not flammable themselves, but this should not lull our vigilance. Oxidisers do not need to burn in order to intensify the development of a fire involving other substances.

Let us look at an example of an extremely dangerous combination. Besides a deceptively similar name, oxygen and acetylene share a very high explosiveness. Oxygen is the basic oxidiser, while acetylene is a highly flammable gas. Combined with oxygen, it reaches one of the highest temperatures of all combustible gases, which can climb as high as 3300°C. Both gases are invisible, but technical acetylene has a sharp, unpleasant smell, which lets you detect it in the event of a leak. If both substances leak at once, a fire or explosion will spread instantly, at the same time producing a shock wave.

## How to properly organise a chemical storage area?

The basis is to separate substances that could cause a dangerous reaction if they came into contact. Oxidisers should be stored away from combustible materials or substances, at a minimum distance of 6 metres. All cylinders must be stored upright and secured against falling. They should also be sorted by type of gas and divided into used and full ones.

Acids and bases should be separated wherever their contact could lead to a violent reaction. The proper placement of chemicals should follow from the information in the safety data sheets and from an assessment of storage conditions. Depending on the type and quantity of the products stored, specialist cabinets, designated zones or separate rooms may be necessary.

To store liquid chemicals such as acids or bases safely, let us remember to keep them separate. Every substance must be in a tight container, preferably the original or a dedicated one, that is resistant to its effects. Remember that chemicals must never be decanted into drink bottles. If a substance is in a dedicated container, let us make sure it is labelled correctly, so that it tells us what substance we are dealing with and what hazards it carries. It is important that every substance has its own up-to-date safety data sheet!

There are several conditions a cabinet must meet for hazardous substances to be stored in it properly. Efficient mechanical ventilation is required, providing as standard 3–6 air changes per hour. The floor must be impermeable to liquids. Cabinets for storing chemicals must be suited to the type of chemicals stored. Special fire-resistant cabinets are used for storing flammable materials and oxidisers. A spill containment tray should be placed under the cabinet, also suited to the properties of the chemical. The tray should have a capacity equal to at least 110% of the volume of the largest container stored in it, or at least 25% of the volume of the cabinet. This way, in the event of a leak, we avoid overflowing the protective container.

## What to do if a chemical is spilled?

First of all, stop work and assess the situation from a safe distance. You must warn people nearby, restrict access to the affected area and establish which substance has just leaked. The container label and the safety data sheet (SDS) will help, in particular its section 6, which describes what to do in the event of accidental release. If there is a risk of poisoning, fire, explosion or a dangerous atmosphere forming, move to a safe place, warn others and call the appropriate services. Do not enter the vapour cloud or attempt rescue actions without proper training and equipment.

A small leak may be cleaned up by yourself only if the substance has been identified, the hazard has been assessed, and the worker has been properly trained and equipped with personal protective equipment and a spill kit.

Special materials called sorbents are used to clean up leaks. A sorbent is a material designed to absorb or bind a spilled liquid, which can then be easily collected from the surface and safely disposed of. Remember that choosing the right sorbent for the situation is important.

Not every sorbent is suitable for every product. A yellow or red sorbent is intended for hazardous substances such as acids, bases and corrosive substances. A blue or white sorbent absorbs hydrophobic substances, that is, oil, crude oil and petroleum products. A grey sorbent is universal, intended for milder chemicals, and absorbs water-based liquids as well as oils and coolants.

**Proper storage of chemicals and preparation for a possible leak reduce the risk, but do not eliminate it entirely. A worker may still be exposed to contact with a hazardous substance during its transport, dosing or everyday tasks. That is why in the next part of the OH₂S series we will look at personal protective equipment and check why its correct selection should always follow from the type of hazard we are dealing with.**