best air filter for old homesWhat is the best air filter for old homes?

If you live in an old house, the indoor air quality issues may be different from those found in a modern home. Unless a great deal of refurbishment or rebuilding has been done, an older home has less insulation and more cracks in the walls, doors and windows. Therefore, damp and accompanying mould spores may be an important element in indoor pollution as well as a constant influx of traffic related pollution. So what is the best air purifier for old homes?

In the modern home, with its energy efficient insulation, indoor air pollutant of a different kind are more likely to build up – because of lack of ventilation (modern houses are often compared to living in a plastic bag) – increasing exposure to a mixture of pollutants including Volatile Organic Compounds, such as formaldehyde, tobacco smoke (if smoking is allowed) and nitrogen dioxides from gas appliances. People in very modern buildings, whether home or office, may experience a cluster of symptoms known as Sick Building Syndrome (SBS). The symptoms of this poorly understood condition range from chronic fatigue and headache to sore throat and lack of concentration. Buildings both old and new are also permeable to pollution coming in from outside, such as pollen grains and particles from traffic exhaust – the latter being a particular problem if you live near a busy road or a large city.

Whatever the age of your house, and the type of indoor air pollution you are exposed to, the use of a proper air purifier will improve the air quality in the building and can significantly reduce any symptoms you may experience. There are two main types of air purifier:

  • High Efficiency Particulate Air (HEPA) filters. These are mechanical air purifiers containing a filter which captures the widest range of particles including pollen grains, mould spores, cigarette smoke and house dust mite. The filters are designed to remove particles by three different mechanisms: interception, impaction and diffusion, each of which is best at removing particles of a different size. A ‘true’ HEPA filter has a Minimum Efficiency Reporting Value of between 17 and 19 which, according to the United States Environmental Protection Agency, has an efficiency between 99.97 per cent and 99.999 per cent in removing particles of 0.3 microns in size (these are the ones that are least likely to be removed by the filter and particles of this size are used to test its performance). Note that a HEPA filter can only remove particles. If gaseous pollution, like formaldehyde, is a significant component of your indoor air pollution, then go for an air purifier that combines a chemical adsorbent, for the gases, with the HEPA filter.
  • Electronic air purifiers. There are two types, both of which give an electric charge to the pollutant particle. An electrostatic precipitator draws air into the system where the particles are charged and attracted to plates within the machine which bear an opposite charge. Ion generators release ions into the air which then attach themselves to airborne pollutant particles and charge them up. These charged particles then stick onto surfaces like walls or curtains, or combine with other particles and these heavier particles settle on the floor. Some ion generators are capable of producing ozone, which is itself a powerful pollutant that affects the lungs – these should not be purchased with a view to improving indoor air quality. As with the HEPA filter, electronic air purifiers can only remove particulate, not gaseous, air pollution.

So, if you live in an old home, first tackle the sources of indoor air pollution – like damp, or products that give off formaldehyde (such as foam-backed carpet) – and then consider which is the right air purifier for you. The model you choose will depend upon the pollutants you need to get rid of, and on the size and number of rooms where the air needs to be cleaned.  A good unit for the removal of mould is the Blueair range of air purifiers, which use ionisation in combination with a particle filter.  If you are not sure about exact type of pollution you want to remove, or you would like to remove a broad range of air borne pollution, we recommend the IQAir rage of air purifiers. The IQAir air purifier's medical filtration will virtually take all particle pollution out of the air and also provides best in class filtration for chemicals, odours and gases.