What does low-VOC paint mean, and how do you read the label?

"Low-VOC" means a paint contains relatively little of the solvents that evaporate as it dries. It is a useful prompt to look closer, but the phrase on the front of the tin is not the number that counts. Turn the tin round. UK regulations require the label to state the product's sub-category, the legal limit for that sub-category and the product's maximum VOC content, in grams per litre.

That figure lets you compare two tins directly, as long as you compare like with like. Here is how to read it, what it does not tell you, and what to do about the smell on the day.

What a VOC is

VOC stands for volatile organic compound: a carbon-based chemical that evaporates easily at room temperature. In paint, VOCs help the product flow and dry. Designing Buildings lists paints, lacquers and paint strippers among the household sources, and notes that exposure can cause irritation of the nose, eyes and throat, as well as nausea and headaches.

Public Health England's 2019 review, UK guidelines for VOCs in indoor spaces, proposed guideline values for selected compounds in homes and offices. Part of its stated purpose was to inform talk about controlling these chemicals at source, which in a decorating job mostly means your choice of product and how much air you let through the room.

Reading the label, line by line

The rule comes from regulation 5 of the 2012 VOC regulations. On a typical label you are looking for a short block of small print, usually near the safety information, with two parts.

The first part names the sub-category and its limit. The second gives the most VOC this product contains when ready to use. If a matt wall paint says its limit is 30 g/l and it contains a maximum of 1 g/l, that is a very different product from one which sits right up against the limit, even if both carry friendly wording on the front.

The limits, and why a low figure is relative

The legal ceilings vary widely by product type. These come from Schedule 2 of the regulations, as originally made. Legislation can be amended, so check the current version if you need the figure for anything formal.

Three things follow from that table. A water-borne trim paint is allowed more than four times the VOC of a matt wall paint, so "water-based" does not mean a door paint and a wall paint are equal. A shinier wall paint falls into a sub-category with a higher ceiling, which is one reason it is worth asking whether you need the shine. Our guide to finishes covers the regulation's gloss line. And the gap between water-borne and solvent-borne is greatest in primers and varnishes, so that is where a swap can change the most.

What the number does not tell you

The label figure describes what is in the tin. It says nothing direct about how quickly the paint gives off those chemicals in your room, whether other substances are present, or how strong the smell will be. A paint can smell quite noticeable and still have a low figure, or smell of little and contain more than you would guess. Your nose is a poor gauge in both directions, and fresh air is cheap whatever the label says.

Nor does a low figure settle how a paint performs. That depends on the product, and on how well the surface has been prepared. Anti-mould additives, fragrance claims and "breathable" wording are all separate matters and need reading separately.

On the day: air first

Designing Buildings' advice is plain: make sure there is plenty of fresh air and ventilation while painting. In practice:

• Open windows on opposite sides of the room or the house if you can, so that air moves through rather than sitting. A single window in a small bathroom will need the extractor fan running as well.
• Keep the door to the rest of the house closed while you work, so the air leaves through the window rather than travelling upstairs.
• Paint bedrooms early in the day and leave them airing for as long as you can before anyone sleeps there. We could not find an official figure for how long to wait, so treat "until the smell has gone" as a minimum.
• Stop if you get a headache or feel sick, and go outside. If the symptoms do not clear, or you have asthma or another lung condition and are worried, ask your GP or a pharmacist, or ring NHS 111.

Strippers deserve more care than paint, especially on old woodwork. If you are taking off layers in an older house, read our guide to lead paint first, since the dust and fumes there are a bigger concern than the solvent in a new tin.

Buying less, wasting less

Fewer litres also means fewer VOCs and less waste. Measure the wall, read the coverage on the tin and buy to suit. Then think about what is left over. Community RePaint, a network of paint reuse schemes, says more than 50 million litres of paint are wasted a year, most of it incinerated. It also warns against the two habits that seem easiest, the general bin and the drain, since both cause contamination.

The same page explains the local catch. Many household recycling centres will not take liquid paint because of the ban on sending liquids to landfill, and they usually ask you to dry it out first, for example with soil or sawdust in the tin. Some areas have reuse drop-off points where usable paint can go to someone else. Rules differ from one council to the next, so look at your council's waste page before you load the car.

Brushes and rollers

Wipe as much paint as you can back into the tin, then onto newspaper, before washing anything. Use a bucket rather than a running tap for the first rinse of a water-based brush, and let any solids settle. For solvent-based paint, follow the tin's instructions for cleaning and do not pour used white spirit down a sink. Ask your council how it wants that taken.