Indoor air pollution

What causes poor indoor air quality?

The quality of the air we breathe indoors is affected by many things. On this page we explore the most common causes of indoor air pollution and how you can avoid them.

The air indoors can be affected by:

The air indoors can also be affected by how a building is ventilated, room temperature, damp and condensation, and pollution that has come indoors from outside. Many people also experience allergies to things in their home such as dust mites and their pets. 


Can the chemicals in cleaning products affect my lungs? 

We use a wide range of household chemicals every day to clean and decorate our homes. These products can contain chemicals sometimes called VOCs - volatile organic compounds. Other cleaning products may contain bleach or ammonia.

VOCs evaporate into the air when we use them or sometimes even while they’re being stored. Products with fragrances such as citrus and pine can react when they are released into the air, forming new chemicals.  Some examples of VOCs are acetone, xylene and formaldehyde. It’s a good idea to avoid breathing in too many VOCs.

More rigorous research is needed before we can be certain about the effects of breathing in these chemicals in our homes. About half of studies suggest that being exposed to these chemicals increases your risk of developing an allergy or asthma.

One study recently found that women who clean at home or work have also been found to have an increased decline in their lung function.

If you use irritating cleaning products, such as those based on bleach, particularly if you apply them with a spray, you may get respiratory irritation and symptoms if you have a long-term lung disease. Studies have also found that if you use these products over a number of years it may cause asthma.

Formaldehyde is a VOC. You can sometimes find formaldehyde in carpets, furniture, shelving and flooring. It can irritate your lungs. This can be why some people say the smell of a new sofa or soft furnishing sets off their allergies or makes their asthma worse.

If this applies to you, try to avoid products containing formaldehyde. Products containing formaldehyde should be clearly labelled under EU regulations.

Where can I find VOCs?

You’ll find these chemicals in cleaning and DIY products, such as:

  • detergents
  • furniture polish
  • air fresheners
  • carpet cleaners
  • oven cleaners
  • pesticides and fungicides
  • paints and paint strippers
  • varnishes
  • glues

What can I do to avoid cleaning products with VOCs?

If you believe the chemicals you use in your home affect your health, there are a few things you can do.

  • Consider other ways of cleaning. The best way to avoid coming into contact with chemicals found in cleaning products is not to use them. If you can, use a damp cloth to clean instead.
  • Avoid chemical-heavy products. Look for products that are labelled allergy friendly, as these have lower levels of volatile chemicals and are usually fragrance-free.
  • Investigate using ‘natural’ paints. But be aware paints advertised as water-based or low VOC may still contain hazardous chemicals.
  • Avoid sprays. When possible, use solid or liquid cleaning products rather than sprays. Sprays get into the air, which means you can breathe them in more easily and they can get further down into your airways. If you think the smell of cleaning products triggers your symptoms, go for unscented products.
  • Ventilate your home. Always open a window when you are cleaning or decorating to make sure there is plenty of ventilation.
  • Bear young children in mind. Babies and very young children are more affected by chemical emissions than adults.
  • Read the label. Finally, always remember to follow advice on the labels of products about how to use them safely. Dispose of partly-used containers through your local recycling centre.

How does heating and cooking affect indoor air quality?

Cookers, heaters, stoves and open fires can release pollutants into your home.

Remember that inhaling any smoke is harmful. 

Heating and cooking can release two types of pollutants:

  • particulate matter (PM) – microscopic particles of dust and dirt in the air
  • gases – carbon monoxide, nitrogen oxides, sulphur dioxide

Exposure to these pollutants can lead to lung and heart disease. 

Once these pollutants are in your home, it’s essential to air your home with fresh air from the outside to dilute and remove them. That’s why gas heaters and cookers that have a flue, chimney, or other kind of vent that allows the polluted air out of your home, are better for lung health. Chimneys from solid fuel stoves and fireplaces need to be cleaned and swept regularly by a registered sweep. If this isn’t done devices become less efficient and carbon monoxide can build up.

Burning wood and coal

Burning wood and coal in a stove or on an open fire releases particulate matter. This can irritate your nose and throat, giving you a cough or breathing problems. It also causes early deaths from lung and heart disease.

If you have asthma, your symptoms might get worse. If you have COPD, it makes you more likely to have a flare-up. In the long term, your risk of getting lung cancer is also increased from burning coal or wood. 

If you live in an urban area, burning wood or coal, will add to outdoor urban air pollution.  Open fires produce greater emissions than stoves. 

Burning wood accounts for 23 to 31% of the particle pollution in London and Birmingham. Other cities will have similar levels as a result of burning wood. This problem is much worse on winter evenings.

Studies have shown that smoke from wood heating enters neighbouring homes too.  UK researchers have also suggested that wood burning in densely populated areas may lead to PM exposures comparable to those from traffic sources.

To reduce particulate pollution from burning wood, smoke control areas cover the UK’s largest cities. Ask your local council’s environmental health department to find out if you live in a smoke control area. If you do live in a smoke control area, this will restrict what you can burn and the types of stove you can use, although many wood-burning stoves are exempt from the requirements.  Find out what you can and can’t burn in a smoke control area.

There’s controversy about using wood-burning stoves, and the UK government has consulted about their use as part of their Clean Air Strategy. Given the contribution to environmental pollution, carefully consider the issues before you buy a new stove.

What about gas or electric heating and cooking methods?

When you cook with either gas or electricity, tiny particles are also released that are easily inhaled. Higher concentrations of these particles are released when cooking with gas. Gas cooking also produces gaseous emissions, including carbon monoxide, formaldehyde and oxides of nitrogen, all of which can cause respiratory health problems.

Carbon monoxide

The most dangerous pollutant is carbon monoxide, which can kill you within a few hours. It’s a poisonous gas with no smell or taste. Carbon monoxide is created when fuels like gas, oil, coal or wood don’t burn fully. It’s important to make sure cooking and heating appliances are serviced regularly, and that vents and chimneys are not blocked. Although carbon monoxide does not have a smell, if an appliance isn’t working properly it may produce more soot.

If you have mild carbon monoxide poisoning, the first symptom you might notice is a headache. You might also notice flu-like symptoms, but without the temperature.

If several people in one building develop flu-like symptoms without a temperature, then it could be due to a carbon monoxide leak – so act immediately. Switch off all gas appliances and ventilate the property. Call the gas emergency number 0800 111 999 or the Health and Safety Executive Gas Safety Advice Line on 0800 300 363.

How can I reduce the pollution produced during cooking and heating?

  • Make sure all your gas appliances are regularly maintained by a certified engineer.
  • Install extractor fans over your gas stoves and ranges, and always use them.
  • Avoid open fires and wood-burning stoves. If you can, use gas or electricity to cook and to heat your home.
  • If you must burn coal or wood, make sure the chimneys are inspected and swept regularly by a HETAS qualified sweep. If you’re thinking about buying a wood-burning stove, please think about the outdoor air pollution it will cause to your neighbours’ air quality and to the quality of the air entering your own home. And if you go ahead, choose a modern, lower-emission one. Only burn dry, unpainted and untreated wood. Look for wood with the ‘ready to burn’ logo. Don’t burn rubbish or packaging as this can create toxic substances. Lighting your fire with plenty of kindling and ensuring a good air supply in your stove fire box will reduce the particle emissions. In the future, the government will only allow the very cleanest stoves and fuels to be bought.
  • Avoid buying a wood-burning stove or using an open fire if someone in your household has a lung condition or if you live in a town or city.
  • Install alarms for both smoke and carbon monoxide - these are separate alarms. Check the batteries regularly.
  • For additional advice you may want to read the Department for Environment, Food and Rural Affairs’ practical guide on open fires and wood-burning stoves. 

Don’t light several candles or incense sticks in a small room such as a bathroom.

Candles and incense

Candles and incense sticks also emit particles and other pollutants when they burn. There is evidence linking incense burning to lung disease so high levels of exposure should be avoided. Incense sticks emit more than 100 times the number of fine particles as a candle. A single candle in a living room can also substantially increase the particle concentration in the air while it’s burning, but over a 24-hour period the increase is minimal.  Scented candles emit small amounts of formaldehyde and VOCs but if you only use them occasionally, are unlikely to pose much of a health risk.


How can building materials affect air quality?

The most significant building material with lung health risks is asbestos, which has been banned in the UK since 1999. But older properties may still have asbestos-containing materials.

Before its dangers were known, asbestos was often used in buildings for insulation, flooring and roofing and sprayed on ceilings and walls. If you breathe in asbestos fibres, this can lead to lung diseases decades later.

What should I do if there’s asbestos in my home?

If you find asbestos in your home, make sure it remains undisturbed. If it’s damaged or deteriorating, get it removed by accredited professionals.

Fibreglass and other synthetic mineral fibre products can release fibres when trimmed, cut or sanded. These products are often found in the loft space in homes. Larger fibres could irritate your skin, nose and throat. If you discover fibreglass in your home, don’t disturb it. If you come into contact with it, wear a mask and protective clothing.

Building materials can also contain VOCs (volatile organic compounds.) These include roofing and flooring materials, insulation, cement, coating materials, heating equipment, soundproofing, plastics, glue and plywood.

How can the land on which my home is built affect the air quality?

If your home is built on ground with a higher level of radon, you can take measures to reduce it. You can find out if your home is in a radon-affected area at UKradon.

What is radon?

Radon is a natural radioactive gas that comes from rocks and soil. It’s colourless and odourless.

Certain areas of the UK have higher levels of radon. The radon level in the air we breathe outside is very low, but it can be higher inside poorly ventilated buildings.

High levels of radon can cause lung cancer. The higher the level of radon, and the longer you are exposed, the greater the risk will be.

Indoor radon often varies from building to building. If your home is affected, UKradon has a tool to help you decide if you need to reduce the level and how. 

Which are the safest building materials?

Consider using building materials with low VOC emissions. Look for products and materials that show they are environmentally friendly and low in pollutants and emissions. You can find sustainable products on the website of The Alliance for Sustainable Building Products.

If I have asthma or COPD, what should I do if there is building work in my home?

If you - or anyone working in your home - use materials that might trigger your symptoms, keep your home well-ventilated during the building work and for a few days afterwards.

Ask the builder to do preparatory work such as cutting or mixing materials outside. You might even want to consider moving out while the work is going on.


Tobacco smoke in your home 

Smoking is the main cause of preventable illness and preventable death.

Second-hand tobacco smoke is also bad for our health. That’s why laws have banned smoking in enclosed public spaces, including public transport and workplaces, and in cars with children.

If anyone smokes in your home, tiny particles from tobacco smoke can drift all through your house. These particles can remain at harmful levels for up to five hours.

What are the effects of tobacco smoke?

If you breathe in this smoke, your nose or throat can get irritated and you might cough or have trouble breathing.

If you have asthma, your symptoms are likely to get worse. And if you have COPD, you are more likely to have a flare-up. In the long term, your risk of getting lung cancer is also increased.

Children are particularly at risk. Breathing in tobacco smoke affects how their lungs work and makes them more likely to develop a long-term lung condition when they grow up.

Using e-cigarettes is less harmful than tobacco smoking, but these devices are not completely harmless. If you decide to use an e-cigarette at home, it should be kept out of reach of children and if you are a parent or carer you should consider the benefits and drawbacks of permitting vaping in the home.

What can I do about tobacco smoke in my home?

  • Don’t smoke indoors, and don’t allow others to smoke in your home.
  • Don't smoke around children and make sure anyone looking after your children also doesn't smoke when they are with them.
  • If you smoke at home, rather smoke outside, close the door behind you and move away from the side of the house.
  • If you smoke, the most important thing you can do to improve your health is to quit.

Next: Allergies in the home >

Download our indoor air pollution information (302KB, PDF)

Last medically reviewed: September 2018. Due for review: September 2021

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.