People should open windows when they cook and stop drying clothes indoors to reduce air pollution in their homes, health chiefs have warned.
Official advice published today by the NHS regulator said people need to protect their health by reducing pollution in their homes.
This may come from cooking, damp, aerosols, fires, smoking or cleaning products, according to the National Institute for Health and Care Excellence (NICE).
These can be a 'considerable' source of pollution, government directors say, and can irritate the lungs or trigger asthma.
NICE's advice tells people to keep windows open or use extractor fans when using cookers, candles, aerosols, cleaning products or when having a bath or shower.
They should avoid air-drying clothes indoors but, if there is no choice, a window should be opened to let out the damp air.
The report said people should 'avoid moisture-producing activities' in general.
Although not thought of as an immediate danger, asthma can last for a lifetime, cause serious breathing difficulties and even fatal attacks.
More than five million people already have the condition in the UK.
Pregnant women, young children who spend a lot of time at home, older people and those with long-term illnesses may be most vulnerable to indoor pollution.
Tenants who rely on a landlord to make repairs, or people who live in poor-quality housing may also be more likely to suffer the damaging effects.
And other risks include living in a place with small rooms, too many people, damp or mould, or so much noise or pollution outside that people avoid opening windows.
NICE's guidelines also issued advice to local councils, architects and landlords for how they should make houses safe to live in.
Properties should be designed with windows that can be opened, good ventilation and extractor fans.
And issues such as mould and damp should be fixed quickly, the health bosses said.
As extra precautions for pregnant women, the report added mothers-to-be should avoid household cleaning sprays, air fresheners and candles.
Candles, incense and aerosols can cloud the home with particles called volatile organic compounds (VOCs), which are toxic over long periods of time.
