Indoor air pollution

Indoor air pollution is mostly more polluted than outdoor air pollution, yet it receives far less public attention. As we often spend up to 90% of our time indoors (at home, work or at school), exposure to indoor air pollution is damaging our health in a more significant way. That is why the World Health Organisation considers indoor air pollution as one of the main health threats today, and states that around 3% of the global burden of disease is directly attributable to it.

FAQ about Allergies:

Indoor air pollution is a complex mixture of substances in the air that are potentially very harmful to health. The composition of this indoor air pollution mixture can vary greatly. For instance in a home in a non-urban setting, house dust mitepollen and mould spores can be a major cause of indoor air pollution. In a new-build home or office, it is mostly the off-gassing fumes from wall paints and insulation, new carpet and furniture that are significantly contributing to the pollution mix. Traffic and industry pollution also play an increasing part in indoor air pollution, especially in urban settings.

The size of the particles found in indoor air pollution range from 100 microns to smaller than 0.01 microns. The heavier particles tend to settle as dust but are easily stirred up again when someone walks through a room or even when a surface is dusted; damp dusting, not dry dusting, is needed to actually remove dust rather than just spread it around. Most carpets are a major reservoir for dust and for every six rooms in a house around 40 pounds of dust is generated in a single year.

The main components of dust which can affect your health indoors are:

  • House dust mite
  • Mould spores
  • Pollen grains
  • Soot
  • Pet dander
  • Particulate cigarette smoke

From 0.1 microns and smaller, pollution falls into the nanoparticle and molecular size range. Among the major sources of invisible gaseous and chemical pollution are:

  • The gaseous, non-particulate components of cigarette smoke.
  • Other combustion products such as carbon monoxide and nitrogen oxides from boilers and cookers.
  • Volatile Organic Compounds such as formaldehyde, which slowly 'outgasses' from Medium-Density Fibreboard often used in DIY or flat pack furniture, or carpet.
  • Volatile Organic Compounds are also found in a wide range of household products ranging from aerosol toiletries to paint.
  • Radon is a radioactive gas that is found in homes in certain parts of the country, if they are built of rocks containing uranium which naturally decays to radon.

  • Exposure to indoor air pollution can trigger attacks of asthmahay fever and other allergic conditions.
  • The adverse health effects of Second-Hand Smoke are well known: they include triggering asthma and increasing the risk of lung cancer. Exposure to radon has also been linked to lung cancer.
  • Exposure to Volatile Organic Compounds contributes to 'Sick Building Syndrome' and Multiple Chemical Sensitivity which are poorly understood chronic conditions marked by symptoms such as lack of concentration, headaches and fatigue.
  • Research has also shown that exposure to combustion products from wood burning stoves and gas cookers can have a number of adverse effects on heart and lung health.

Preventing indoor air pollution is sometimes easier than reducing or removing it.

  • If you smoke, it is best to do so outside and to ask smoking visitors to do likewise.
  • If you suspect you live in a radon-affected area, get the radon level in your home tested and take appropriate corrective advice and action.
  • Check any DIY products or household aerosols for VOC content. Read the label and note whether the product should not be used in an enclosed space. There are often more 'environmentally-friendly' alternatives to conventional paints, glues and similar products, so choose wisely.
  • Avoid MDF and other products which release formaldehyde into an enclosed environment.
  • Keep humidity low to discourage mould and house dust mite.
  • Use effective air filtration to target particular pollutants.

What role does ventilation play in reducing indoor air pollution?

Letting fresh air into the home, and releasing polluted air should be part of your strategy for improving indoor air quality. The exception is going to be if one of the main sources of pollution is coming from the outside – which unfortunately is often the case. We would recommend opening windows after bathing, showering or cooking so that damp and mould don't build up.

An effective air purifier will play an essential part in reducing indoor air pollution in your home or place of work. A mechanical air purifier fitted with a High Efficiency Particulate Air (HEPA) filter can remove over 99.5% of particles down to 0.003 microns in size. Electronic air purifiers rely upon placing electric charges on the particles so they stick to a surface either in the room (ionising air purifier) or inside the machine (electrostatic precipitator). The performance of these air purifiers will significantly vary. To remove gaseous and chemical pollution an absorbent material, such as activated charcoal, will need to be integrated into the air purifier. Otherwise, only particulate pollution will be removed.

What other tips will help cut down indoor air pollution?

  • Damp dusting traps dust better than a dry duster, which just spreads it around.
  • Getting rid of clutter, which attracts dust, will help remove mould spores, bacteria and house dust mite. Clutter includes old papers, old books and ornaments.
  • Carpet is a prime reservoir for house dust mite. Consider replacing your carpets with hard flooring.
  • Invest in a leakage free HEPA vacuum cleaner. When it comes to indoor air quality, your vacuum cleaner can be one of your best friends or worst enemies. To see the range of vacuum cleaners we recommend, visit our allergy vacuum cleaner page.

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