You remember the smell.

The mattress came sealed in plastic, and when you cut it open there was that chemical newness in the air. So you did what everyone does. You stood it up by the window, cracked it open, let it breathe for a day or two. The smell faded. You made the bed and moved on.

Here's the part nobody mentions: the smell was never the whole problem.

Some chemicals in a mattress are fast. They evaporate quickly, they smell, and airing out a room can clear a lot of them. Others are slower. They may not smell like anything at all, but they can still gradually move out of the materials around us.

Two studies published in April 2025 looked at chemicals in children's sleeping environments. The researchers found higher concentrations of several chemicals in the air immediately around where children slept than in the wider bedroom. They also found that some of these chemicals were coming from the mattresses themselves.

What did the researchers actually find?

Researchers from the University of Toronto looked at the question from two angles.

First, they studied the bedrooms of 25 children between six months and four years old. Small chemical-collecting sensors were placed in the bedroom and in the child's sleeping environment, close to the mattress.

They found chemicals in both places. But concentrations of several compounds were higher in the sleeping environment than in the bedroom air.

In other words, the air right around where a child sleeps can be different from the air across the room.

Then they went looking for the source.

In the second study, they bought 16 new children's mattresses and tested the foam and covers. They found 21 different semivolatile organic compounds, or SVOCs. The name sounds complicated, but the basic idea is simple: these are chemicals that can slowly move out of materials and into the air, dust and surfaces around us.

The chemicals did three basic jobs:

• Plasticizers, which are used to make materials softer and more flexible.
• Flame retardants, which are used to make materials harder to burn.
• UV filters, which help protect materials from breaking down when exposed to light.

Some of the results were particularly concerning. One mattress exceeded Canada's regulatory limit for a type of phthalate called DnBP. Five contained other phthalates at levels above Canada's limit for children's toys, even though those particular limits do not apply to mattresses. And one mattress contained a high level of TCEP, a flame retardant prohibited in Canada since 2014.

The researchers also found flame retardants in several mattresses even though they are not needed to meet flammability requirements in either Canada or the United States.

Why does it get worse when a child lies down?

This is the finding that stayed with us.

The researchers tested some of the mattresses at room temperature, then warmed them to approximately body temperature. They also applied weight to simulate a sleeping child.

The number of chemicals detected increased as the mattress was warmed and compressed.

A mattress sitting empty in a shop is not doing exactly what a mattress does at 2am.

Warmth can increase the release of these chemicals. So can pressure.

A sleeping child is warm, close to the mattress surface, and there for hours at a time. That doesn't mean every chemical detected reaches a child's body at a harmful level. It does mean that the sleeping environment deserves more attention than simply asking whether a mattress smells when you first open it.

Why are children more vulnerable to exposure?

There is a simple reason to pay particular attention to young children: they spend a lot of time sleeping, and their bodies are still developing.

Young children also take in more air relative to their size than adults. The researchers note that children breathe at around ten times the rate of adults. Their skin is also more permeable, with about three times the surface area relative to body weight.

The chemicals found in these studies include substances that have been associated in previous research with concerns around endocrine disruption and other health effects. Those associations do not mean that these particular mattresses were shown to cause those outcomes. The studies measured chemical exposure, not illness.

That distinction matters.

The researchers' concern is that children are being exposed to chemicals in their sleeping environment, sometimes from products that contain substances that are restricted or not necessary for the product to perform its basic function.

So why don't we know what's in a mattress?

Because there is surprisingly little information available to parents.

A mattress can tell you its size, its materials and how much foam it contains. But that doesn't necessarily tell you every substance added during manufacturing, what was used to treat the cover, or which additives are present in the finished product.

And the researchers found another problem: mattresses from the same brand could have different chemical profiles when purchased at different times. In other words, even knowing what one version of a mattress contains doesn't necessarily tell you what is in the next one.

This isn't a story about one bad company.

It is a story about a much bigger gap in consumer information.

We are generally told what a product is made from. We are much less often told what was done to those materials along the way.

What did the researchers suggest parents do?

Their recommendations are refreshingly ordinary.

What about the layer above the mattress?

This is where the research connects to something we can speak about, because AIZOME makes that layer.

We don't make mattresses, and we can't tell you what's inside yours.

What we can tell you is what's in the fabric that sits directly above it.

At AIZOME, we think the important question isn't only what a textile is made from. It's what happens to it along the way.

Our cotton starts with certified organic fibre from Turkey. It is dyed with plants including indigo, madder and gallnut using water and soundwaves rather than conventional synthetic dyeing chemistry. The finished fabric is independently tested, and every piece carries a batch number that can be traced back to its production records.

Our fabrics carry the STANDARD 100 by OEKO-TEX® Product Class I certification, the strictest product class, intended for babies and small children. They have also been tested by TÜV SÜD for PFAS, with none detected in any of our colours.

You don't have to take our word for it.

That's the point.

The takeaway

You can't easily audit what's inside a mattress. That's the honest answer, and no bedding company should pretend otherwise.

But you can decide what goes on top of it.

And you can ask about that layer the same question these researchers asked about mattresses:

Not just what is it made of, but what was done to it, and who checked?

You can ask that tonight.

It costs nothing.