Unhealthy Air

  • 11 November 2011
  • Home Energy Centre
Solvents, allergens, toxic spores - you could be inhaling them all.

When you think about air pollution, car fumes, smog and fumes from factories probably spring to mind. But, the reality is, the air inside your home could be more polluted than the air outside.

In many New Zealand homes - particularly newer ones - building materials, carpets and other finishings and furnishings emit chemicals that can be harmful to your health. These chemicals can cause asthma and a range of other ailments.

You can protect yourself and other members of your household by choosing the materials used in your home carefully, and by making some simple lifestyle choices - such as keeping your carpet clean.

Why do pollutants matter?

The health impacts vary according to the type of pollutant but can include asthma, headaches, fatigue, coughing, sneezing, dizziness, and eye, nose, throat and skin irritation.

The effects of pollutants can be acute and immediate (for example, allergens from dust mites) or chronic over a long term (for example, formaldehyde and spores from toxic fungi).

Exposure can occur soon after occupying a new home and may be ongoing during the life of the house.

While pollutant levels from individual sources may not pose a significant health risk by themselves, many homes have multiple sources of indoor air pollution that can accumulate and interact.

Types of pollutants

Volatile organic compounds

Volatile organic compounds (VOCs) are chemical substances that become airborne (and therefore able to be inhaled) at room temperature. They are emitted by a range of materials and household products including paints, cleaning products and many furnishings.

A common and toxic VOC is formaldehyde which is released from some composite wood products such as plywood, fibreboard (MDF), furniture and glues.

Asthma research has found a link between home exposure to VOCs and incidence of asthma in young children.

In general, you'll be exposed to more VOCs from building materials, furniture and finishings when the materials are new and when conditions are hot and humid.

Some materials emit pollutants continuously, although the quantity can decrease over time.

Other common pollutants

Other common pollutants include:

  • airborne particles from fireplaces, wood stoves, kerosene heaters and tobacco smoke
  • noxious gases such as carbon monoxide and nitrogen dioxide from unflued gas heaters, leaking chimneys, wood and gas stoves, automobile exhaust in attached garages and tobacco smoke
  • airborne sprays from air fresheners, cleaners and pesticides used indoors, and from products used on lawns and gardens that drift or are tracked inside the house
  • biological contaminants from bacteria, moulds, animal fur, dust mites and pest droppings - these create fine breathable particles that contribute to allergies and respiratory disease
  • chemicals used on carpets to repel insects and stains.


Renovation can release toxic substances (such as lead-based paint dust), so check materials at the start and take the necessary advice and precautions. Contact your local Occupational Safety and Health (OSH) office for advice. The OSH website has contact details for local offices and a national freephone number.

Dealing with pollutants

By making informed choices about materials, products and how you live inside your home, you can reduce the levels of pollutants in the air and keep your home healthy.

Choose safe materials

When renovating or building, choose products and building materials with low or no likelihood of toxic emissions. In particular, look for products and materials that:

  • are pre-dried or quick drying
  • are breathable
  • use water as the solvent
  • are classed as having zero or low VOCs.

Read the product's material safety data sheet, and check with your builder and designer about how safe the product is.

See materials for more detail on choosing products and materials for different areas of your home.


Effective ventilation will help to remove airborne pollutants from your home and bring in cleaner air that's healthier to breathe. See ventilation for more detail.

Avoid unflued gas

Don't use gas heaters unless they're vented outside with a flue and don't use gas cooktops without an extractor fan. Burning gas releases moisture inside your home and also releases other pollutants which can be unsafe for you and your family.

Air filters

Air filters may be necessary:

  • where there is a lot of road dust or industrial pollution
  • for people with high chemical sensitivity
  • if pollutants cannot be reduced or ventilation improved.

Daily living options

Other ways to reduce your exposure to airborne pollutants inside your home include:

  • keeping carpets clean so they don't act as reservoirs for dirt, dust mites and pollutants
  • choosing cleaning and maintenance products that don't contain pollutants
  • where possible, controlling pests with non-aerosol, low-toxicity products (such as pyrethrum or essential oils) or using traps
  • sealing problem materials such as composite wood, or lead paint that can't be removed, with low-emission finishes
  • ensuring that any internal door to the garage is well sealed to keep fumes out of the house - ideally there should be two doors between the garage and internal rooms
  • keeping compost heaps and bins away from the house - they can be a source of fungal spores.
Read Unhealthy Air and more.

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