VOCs stands for Volatile Organic Compounds, which describes airborne chemicals. VOCs are both naturally occurring and manmade.

Harmful VOCs can cause health effects in both the short and long term. Health effects vary from minor eye, nose and throat irritations to more serious ailments, depending on the level of exposure to a particular chemical. It is important also to note that VOC sensors also simply detect chemicals associated with human or animal presence. So although some VOCs are not always bad for your health, they are important to monitor if consistently high and to experiment with ventilation.

They come from an array of everyday items including paints and varnishes, wax and cosmetics, cleaning and hobby products, and even cooking. When you have an enclosed space like a home or office, these emitted gases accumulate and can pollute our fresh air. VOCs are actually also produced by humans, and it is useful to monitor total VOC levels in rooms to see when it's a good time to ventilate or identify potential sources.

Anything that burns gives off fumes. Fireplaces and scented candles are especially harmful, so keep an eye on your levels while using them.

Humans and animals also produce VOCs. The sensor detects VOCs in peoples breath (and perfume and other smells)

Mothballs, room deodorizers and perfumes—anything with a fragrance, contain chemicals that should be avoided.

Cooking also creates gases that can be toxic. Always use a hood fan or open a window while cooking indoors. And keep the door closed when grilling outdoors.

New furniture, carpet, drapes, mattresses all contain chemicals that slowly release into the air, often for years after you bring them home.

While cleaning with soaps, detergents, furniture polish and glass cleaners be aware of terpenes and ethanol and ventilate accordingly.

Glue, paints, fabrics, wax, dyes, many craft products contain VOCs. Be sure to ventilate while using them.

Some hard plastics contain formaldehyde, and new fabrics emit toxins into the air. Look for BPA-free plastics or avoid plastics altogether, and wash toys before using them.

Lacquers, paint, industrial glues, paint thinner and harsh chemicals should not be kept in the home, even when they are locked tight they emit chemicals into the air.

Please see here for an example of how particular VOCs are classified: