VOC vs formaldehyde: what's the difference?

Formaldehyde is a VOC — the confusion comes from marketing that treats them as two separate problems. The difference that actually matters is behaviour: most renovation VOCs evaporate from applied coatings and clear within weeks, while formaldehyde is continuously generated inside the resins of composite-wood carpentry for years. The two therefore need different responses — one mostly needs time and ventilation, the other needs source treatment.

What VOCs are

VOC stands for volatile organic compound — a broad family of carbon-based chemicals that evaporate readily at room temperature. A fresh renovation releases dozens of them at once: toluene and xylene from paints, solvents from adhesives and sealants, and even limonene from the citrus-scented cleaners used at handover. Together they make up most of that sharp "new reno" smell.

Air-quality meters usually report these as a single TVOC (total VOC) number. Treat that figure as a trend indicator, not a health benchmark: it lumps harmless and harmful compounds into one aggregate, and there is no single TVOC standard to judge it against. A falling TVOC over days tells you the paint and solvent phase is passing — it says nothing specific about formaldehyde.

Formaldehyde vs typical renovation VOCs

What this means for treatment

Because ordinary VOCs dissipate on their own, a "VOC removal" package bought in the first weeks after renovation is largely riding on natural dissipation — the air would have cleared on a similar timeline anyway. Formaldehyde is the exception: its source is sealed inside your carpentry and keeps producing gas long after the solvent smell is gone, which is why it needs source treatment rather than waiting.

• Just painted, no new carpentry? Ventilate and wait — the smell is solvent VOCs and it will pass in weeks.
• New built-ins, wardrobes or MDF furniture? Test, and treat if readings are elevated — time alone works on the scale of years, not weeks.

For the fuller timeline of what off-gasses when, see new renovation smell: what off-gasses and for how long.

A note on "VOC-free" and E0/E1 board labels

Lower-emission boards are genuinely better: E1 and E0 grades cap how much formaldehyde a board may emit, and choosing them at renovation time is worth doing. But "low" is not "zero" — the labels limit emission per board, and a home fully lined with E1 carpentry can still sum above the WHO guideline once doors and windows are closed. The label is a starting point; the reading is the answer. See safe formaldehyde levels for what the numbers mean.