# What is dust made of?

I was cleaning my blinds today, and wanted to know what the primary components of dust are. I know that it is made of microorganisms and other particles, but I do not want to guess that it will be $\ce{N}$ or $\ce{Si}$.

I can guess that other materials outside our house might have more than one component for dust. But what about inside the house?

• Interestingly, NIST has several dust standards, such as Urban Dust, Trace Elements in Indoor Dust and Organic Contaminants in House Dust. NIST is pretty much the best source for material analyses you can get, but it seems all the certificates are only for trace substances/elements. – Nicolau Saker Neto Apr 28 '15 at 20:28
• Wikipedia says, "Dust in homes, offices, and other human environments contains small amounts of plant pollen, human and animal hairs, textile fibers, paper fibers, minerals from outdoor soil, human skin cells, burnt meteorite particles, and many other materials which may be found in the local environment." – ron Apr 29 '15 at 2:52

The dust in the house mostly contains sand, dirt and dead skin cells.

First, let's start with the easiest, sand. The chemical formulae of sand is $\ce{SiO2}$, so it contains silicon and oxygen.

Next, dirt has rock, sand, and clay. Sand is made of silicon and oxygen. Rock is mostly made up of graphite (carbon) and some minerals like phosphorus and silicon. Clay is made up of silicon and oxygen and some minor minerals like aluminium.

Lastly, dead skin, like other organic compounds, contains carbon, hydrogen and oxygen, maybe some nitrogen as it may have protein in it.

So basically, dust is made up of carbon, hydrogen, oxygen, nitrogen, silicon, phosphorus and some minor minerals.

• Sand? Do you have a source for that? I don't think it is a particularly common component of house dust, which is what Asker seems to be talking about. Of course, the composition of dust varies wildly with where it is collected, since it is composed of any particle sufficiently small to remain temporarily aloft by air currents. Also, rocks are mostly made out of silicate minerals. – Nicolau Saker Neto Apr 28 '15 at 19:12
• @NicolauSakerNeto Well, the content of the dust will obviously be highly dependent on environmental conditions. For people living near beaches or deserts, there will definetly be a considerable amount of sand. – Molx Apr 28 '15 at 20:16
• While there are many rocks that have some graphite in them, I'm not sure I would say that rock is mostly made up of it, certainly not over silicates. – Michael DM Dryden Apr 28 '15 at 22:09

Dead skin, like other organic compounds, contains carbon, hydrogen and oxygen, maybe some nitrogen as it may have protein in it. So basically, dust is made up of carbon, hydrogen, oxygen, nitrogen, silicon, phosphorus and some minor minerals (Assan Reza chems. Hons.preparing civil service).

## There is no standard dust

The short answer is that dust is composed of particles small enough to be easily lofted by air currents.

The chemical composition varies dramatically from place to place; anyone who says "dust consists of x, y, and z" means "I took a sample, and it consisted of x, y, and z."

For example, the main component of office dust is simply paper; it is a very small component elsewhere. Some sources claim skin cells are a large component; most say they failed to detect more than traces.

In natural environments, soil particles and finely crushed, dried vegetable matter are often major constituents; in artificial environments, both are hugely outnumbered by clothing fibres.