Ventilation and Health

Many buildings, particularly older ones, ventilate naturally by air passing through the building fabric. They also may have a ventilation system of some sort, but the question is “is it used?” You can air your homes by opening the windows. However, indoor air quality deteriorates very quickly when windows are closed again, e.g. when cooking or taking a shower, so we advise you to use whatever ventilation system you have in your home proactively.

The importance of ventilation is clearly recognised within Government backed building regulations that state the minimum levels of ventilation performance required in each home. However, awareness of regulations and ventilation requirements in the UK remains very low and many homes will show evidence of the health damaging side effects of poor ventilation.


If your home has evidence of mould (usually black/discoloured patches on the walls) or if any of the occupants are suffering from respiratory or allergy problems, you should take a good look at the ‘healthy balance’ of your home.

Common symptoms of poor indoor air quality

  • Coughing
  • Sneezing
  • Watery Eyes
  • Fatigue
  • Dizzines
  • Headaches

Deteriorating health, as a result of poor air quality inside the home, can be caused by the following pollutants in your home:

Biological Pollutants

Mould spores (microscopic particles) are found everywhere. They are released into the atmosphere by damp spots on walls, window frames or even decaying food. They can be common in houses which have little or no ventilation. Pollen can be a pollutant factor in your home, usually brought in from outside either by leaving your windows open in high pollen seasons or even by walking around the house in shoes you have worn outside. Dander is tiny particles, which come from feathers, skin, or hair, that may cause allergies.


A lot of everyday cleaning products contain chemicals known as volatile organic compounds (VOCs). VOCs can trigger asthma and are found in air fresheners, carpet cleaners, polish and oven cleaners.


Radon is a natural radioactive gas that comes mainly from the soil. It can enter a home through:

  • Cracks in solid floors
  • Construction joints
  • Cracks in walls
  • Gaps in suspended floor
  • Gaps around service pipes
  • Cavities inside walls
  • The water supply

Carbon Monoxide is a gas that has no odour or colour and can have a serious effect on your health. It is present in homes through:

  • Cooking
  • Heating
  • From the outdoor environment
  • Clogged chimneys
  • Wood burning
  • Incense burning
  • Cigarette smoke
  • Burning candles

Building Materials

Paint can contain lead and formaldehyde which can lead to health problems such as breathing difficulties, increased blood pressure and joint pain.

Asbestos is the name of a group of minerals with long, thin fibres that are so small you can’t see them. If you disturb asbestos, the fibres can float in the air. This makes them easy to inhale, and some may become lodged in the lungs.



If you can heat your home affordably and comfortably then look at your ventilation system to ensure it is working hard enough to improve the air quality in your home. If you don’t have any ventilation system installed, then look at the options below and consider an installation to suit your requirements.

Local Extract Ventilation

The most common method of ventilation in UK homes is a mix of natural and mechanical ventilation, for example trickle vents in the windows and intermittently running extractor fans in wet rooms, the kitchen, bathroom and toilet. Make sure that the trickle vents are open and unblocked and that extractor fans are clean and operating properly.

Don’t shy away from using the boost function if it is available at times when excessive moisture is being produced, e.g. when cooking or taking a shower. If your cooker hood or extractor fan is not working, buy one straight away to prevent further damage to your home and potential damage to your health.

Continuous Mechanical Extract Ventilation

If you have renovated your home with insulation and methods of reducing air leakage through the building fabric, you may find that the Local Extract Ventilation route is not effectively ventilating due to the larger amount of stale air and moisture that is created. In this situation it is best to invest in continuous ventilation which is either in the form of a central box system with ducts to applicable rooms or low level continuous running local extractor fans in the wet rooms. The latter approach is mostly applicable in existing homes where it is difficult to run ducted systems. Please note that although such fans run continuously, they can cost less than £5 per year to run so this is a tiny investment for such an important gain in your home, your personal comfort and your health.

Positive Input Ventilation (PIV)

These are central box systems (usually located in the loft in a house, or on a wall in a flat) with a duct that supplies fresh, filtered air into a landing area or hallway to ventilate the whole property. Rather than extracting air out, this method delivers air into the home to dilute, displace and replace high humidity levels to control condensation.

Mechanical Ventilation with Heat Recovery (MVHR)

MVHR is often applied in new, very air-tight and well-insulated buildings. Like Mechanical Extract Ventilation, they ventilate homes continuously but they give the added benefit of recovering heat from the extracted air and warming up the fresh air supplied to the building. In the future, it is expected that most new homes will be sold with these ventilation systems.

Please bear in mind that MVHR may not be the best solution if your home is poorly insulated and/or you leave your windows open.