Singlet oxygen, simply explained

Anyone who starts looking into oxygen-based wellness devices runs into a term that sounds off-putting at first: singlet oxygen. It reads like a chemistry lecture, and most explanations online are written that way too. The idea underneath is simple. It is not a different substance. It is the same oxygen you are breathing right now — in a different energy state.

Not all oxygen is the same

The oxygen in the air is made of two atoms bonded together: O₂. Familiar enough. It gets interesting at a detail most of us skipped at school. In its normal state, oxygen has a property that makes it unusual among common molecules: two of its outer electrons spin in the same direction. Chemists call this state triplet oxygen.

That sounds like a technicality, but it has one large consequence — and it is the reason this article exists: that arrangement makes oxygen sluggish.

Which is fortunate. If oxygen in its everyday state were as eager to react as its chemistry suggests it should be, the world would look different. Wood, paper, fat — anything that could react with oxygen would do so far faster. The triplet state is the built-in brake.

What happens when the brake comes off

Add energy to the molecule and the arrangement of those two electrons changes. Their spins become opposed. The molecule moves into an excited state — the singlet state.

A picture that holds up well: imagine a rubber band lying loose on a table. That is triplet oxygen. Stretch it, and it stores energy and wants to return to where it started. That is singlet oxygen.

Two things follow. First: the singlet state carries more energy. There is literally more energy in the molecule than there was before. Second: it does not last. A stretched rubber band does not stay stretched. Singlet oxygen returns to its normal state after a short time and releases that energy as it goes. How short depends heavily on its surroundings — millionths of a second in liquids, considerably longer in air.

That return is the whole point. The energy does not disappear. It is handed to the surroundings.

Where this happens in nature

Singlet oxygen is not something artificial. It forms constantly, wherever light, oxygen and a particular kind of pigment come together.

The best-known example is photosynthesis. Inside a plant's leaves sits chlorophyll — the pigment that makes leaves green. Chlorophyll absorbs light energy. Part of it goes to the actual work of photosynthesis. Another part is passed to oxygen molecules nearby, which shift into the singlet state as a result.

A pigment that absorbs light energy and passes it on is called a photosensitiser. Chlorophyll is the most familiar one, and far from the only one. The same thing happens continuously in the atmosphere wherever sunlight meets air.

How a device reproduces the process

This is where it turns technical — and, at the same time, simpler than expected. Once you know that singlet oxygen needs three ingredients — light, oxygen and a photosensitiser — the design of a device follows naturally:

1. Draw in air. The oxygen is already there; it only needs to be moved past something.

2. Pass it over a photosensitiser. In a technical device this is usually a coated element, often described as a catalyst.

3. Illuminate it at a specific wavelength. Not just any light — the wavelength has to match the pigment, or the energy is not transferred.

The oxygen flowing across that surface shifts into the singlet state and back again. Over and over, for as long as air and light are present.

What happens to the released energy is described by the manufacturers of such devices this way: it is transferred to the water molecules in the air — ordinary humidity, in other words — and carried on the airflow to the person using the device, who breathes it in through a nasal cannula. At Forest Air this process is set out in our own documentation; you will find it on the technology page.

Why the design follows from the physics

The reason for that detour through water: singlet oxygen itself is very short-lived. It cannot be bottled, stored or sent down a tube. What leaves the catalyst is not the singlet oxygen itself, but the energy released as it falls back.

That explains why devices built on this principle look different from, say, an oxygen concentrator. There is nothing to dose and nothing to hold in reserve. The process runs while air and light are present, and stops when the device is switched off.

It also explains how the air reaches you. It is not a matter of treating a whole room: the energised air is breathed in directly, through a nasal cannula, the way you would picture an oxygen tube. According to the manufacturer, most people use it in sessions of 30 to 60 minutes a day, and the Pro model serves two people at the same time. Both devices are in the product overview.

What singlet oxygen is not

Three things get confused with one another regularly, and they have nothing in common.

It is not more oxygen. An oxygen concentrator raises the proportion of oxygen in the air you breathe. With the singlet principle the quantity stays the same — what changes is the state, not the concentration. Two entirely different approaches that happen to share the word "oxygen".

It is not ozone. Ozone is a different molecule: O₃, three atoms rather than two. It has different properties, different applications and an entirely different relationship with exposure limits. The confusion is common because both are marketed as "activated oxygen".

It is not ionisation. Air ionisers give particles an electrical charge. That, too, is a separate principle with its own technology.

The whole thing in four sentences

Singlet oxygen is ordinary atmospheric oxygen in a higher-energy state. It forms when light transfers energy to oxygen molecules by way of a pigment — in nature during photosynthesis, in a device by way of an illuminated catalyst. It is short-lived, and it hands its energy to the surroundings as it falls back. And it is neither ozone, nor more oxygen, nor ionised air, however often those get mixed up.

How this is put into practice at Forest Air is set out on the technology page. The two devices — one for the home, one for practices and studios — are in the product overview.

Note: Forest Air devices are wellness devices, not medical devices. Descriptions of the underlying process refer to the manufacturer's own documentation. They do not replace medical or professional care, and we make no health claims.