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Revealed: the hidden air pollution in your home

Which? tests reveal high levels of potentially harmful pollutants in homes, caused by everyday activities such as cooking

Everyday activities such as vacuuming, spraying air fresheners and cooking can all create air pollution in the home that could affect your long-term health, according to tests carried out by Which?.

Our lab technicians tested the air in three ordinary houses of different ages, before and after carrying out everyday household tasks.

We discovered surprisingly high levels of pollutants, with potential cumulative long-term health effects, in all of our test houses.

Read on for more on what we’ve found. You can also read our round up of the best air purifiers tested by Which?, as well as the Don’t Buy air purifiers that just aren’t worth your money.

Indoor air pollutants

The air pollutants our tests uncovered included particulate matter, volatile organic compounds (VOCs) and carbon dioxide (CO2). Some people are more susceptible to the effects of these indoor pollutants – for example, those who suffer from asthma, are sensitive to allergens indoors or have heart and lung disease.

Particulate matter

These particles are released during activities that involve combustion, such as smoking, wood and coal fires, gas cooking and even electric toasters and candles. If inhaled, it can increase the risk of lung and heart disease if the particulate matter is at persistently high levels.

There were large increases in particulate matter in all of our test house kitchens. In our 1950s house the particle counts rose by as much as a factor of 560. This was most likely due to a combination of using multiple gas rings, cooking a fry-up, burning toast in the toaster and introducing flowers – all exacerbated by poor ventilation.

Volatile organic compounds (VOCs)

VOCs evaporate into the air at room temperature, forming vapours that we breathe. They include limonene and pinene (familiar lemon and pine smells used in scented toiletries and bathroom cleaners), which can react with ozone from outdoor air to form the gas formaldehyde and other irritants. Exposure to very high levels of VOCs can cause eye, nose and throat irritation, headaches and nausea and, in the long term, even damage the liver, kidneys and central nervous system.

We found very high levels of VOCs (up to 34 times the UK Building Regulations recommended maximum level – although measured over a busy 30 minutes, not 24 hours) in every room we tested.

Carbon dioxide (CO2)

High levels of carbon dioxide over time can cause sleepiness and impaired thinking, and can particularly affect those with lung problems.

The carbon dioxide levels we measured frequently exceeded the established comfort guidance limits of 1,000 parts per million (ppm). In the kitchen of our Victorian semi they reached 2,950ppm, approaching three times the ‘comfort guidance’ (although measured over bursts of activity rather than a whole day).

Read more on how to improve the air quality in your home.

Indoor and outdoor pollution

Which? scientific adviser Dr Stephanie Kipling says: ‘The quality of the air we breathe outside is constantly monitored. Levels of outdoor air pollution and its health effects frequently make powerful headlines. But step in to your own home, and it’s a completely different story.

‘It’s up to us to take responsibility for our own homes and health. The easiest ways to do this are to maintain good ventilation – for example, maintain adequate background ventilation at all times and don’t block or close existing ventilation provision, such as air bricks.

‘Minimise exposure to these potentially harmful substances – for example, use air fresheners and sprays in moderation.’

It’s also important to look at the relationship between indoor and outdoor air pollution – for example, if you keep your car in an integral garage or live near a busy road. Our car emission tests have exposed the dirtiest and cleanest car makers.

You can read the full article, ‘Breathe Easy?’, in the April 2017 issue of Which? magazine. If you’re not already a Which? member, you can take a £1 trial to Which? to receive the magazine and get instant online access to the current and previous issues.

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