Carpets

Why it matters indoors

A carpet is the one surface in a home that is simultaneously a source, a sink and a habitat. New carpet, backing and adhesive emit volatile organic compounds for a period after installation. After that the emission falls close to background, and the carpet’s role changes: it becomes a store of everything that lands on the floor.

Reservoir, not just a source

Particles settle out of the air onto the floor, and a textile surface holds them where a hard surface does not. That store contains house dust, allergens from dust mites and pets, semi-volatile organic compounds that partition out of the air onto dust, and material tracked in from outdoors. Walking, playing and vacuuming lift part of it back into the air, which is why the concentration measured at the height of a crawling child is not the concentration measured at a metre and a half.

Why the evidence points both ways

Two readings of the same mechanism, both defensible. One: the carpet removes particles from the air and keeps them out of the breathing zone, so a room with carpet can show lower airborne concentrations than the same room with a hard floor. The other: the store is only as good as the cleaning, and it is released exactly when people are most active. The literature on carpet and indoor chemistry and microbiology treats this as an open question rather than a settled one, and the answer depends on the occupants — a household with a person who has asthma or allergy is the case where the reservoir argument tends to win.

What changes the balance

Cleaning frequency and method, the pile type, and whether shoes come inside. A vacuum cleaner without an effective filter returns the finest particles to the air; the coarse fraction it removes is the one that was least likely to be inhaled. The honest summary is that carpet moves exposure around rather than removing it, and that the decision belongs to the household, not to a general rule.