Managing pollution and unhealthy air

Last updated: 9 August 2023

passive ventilation

Solvents, allergens, toxic spores – you could be inhaling them.

Breathe easy in your home

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. We spend between 75 to 90 per cent of our time indoors, more for infants and the elderly.

In many New Zealand homes – particularly newer ones – building materials, paint, glues, carpets and other finishes and furnishings emit chemicals that can be harmful to your health. These chemicals can trigger asthma and a range of other ailments.

Houses that are damp provide the perfect conditions for mould and dust mites to grow. These also have associated health risks.

You can protect yourself and other members of your household by carefully choosing the materials used in your home, keeping your home warm, dry and well-ventilated, 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 irritation of the eyes, nose, throat and skin.

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

Exposure can occur soon after occupying a new home and may be ongoing during the life of the house if the sources are not addressed.

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 interact together.

Types of pollutants

Volatile organic compounds

Volatile organic compounds (VOCs) are chemical substances that become airborne at room temperature and can be inhaled. 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 plywood, fibreboard (MDF), furniture and glues.

Some studies have found a link between home exposure to VOCs and incidence of asthma (see the European Respitory Review website).

In general, you'll be exposed to more VOCs from building materials, furniture and finishes when:

  • the materials are new
  • conditions are hot and humid
  • the house isn’t adequately ventilated with fresh air.

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

Mould and dust mites

According to a national housing survey by BRANZ and Stats NZ, 37 per cent of New Zealand's homes have mould. Mould, with its tiny spores, is at the root of many respiratory illnesses and asthma as well as some forms of gastroenteritis. Dust mites also thrive in humid environments, which can exacerbate allergies in some people.

BRANZ Study Report SR482 - Housing condition and occupant wellbeing: Findings from the Pilot Housing Survey and General Social Survey 2018/19 has more information.

Other common pollutants

Other common pollutants include:

  • airborne particles from fireplaces, wood stoves and tobacco smoke
  • noxious gases such as carbon monoxide and nitrogen dioxide from unflued gas heaters, leaking chimneys, wood and gas stoves, car exhaust gases 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
  • other biological contaminants include bacteria, animal fur 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.

Older homes can have asbestos, in the form of:

  • cement panel products
  • pipes and flues
  • glues and sealants
  • roof cladding
  • insulating board and lagging on pipes
  • decorative texture coatings on ceilings and walls
  • lino or tile backing.

Checking a property for contamination and house condition has more information.

Contact WorkSafe for advice and local contact details including a national freephone number.

Dealing with pollutants

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-finished
  • 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.

Construction systems has more information 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.

Ventilation has more details.

Ventilation is particularly important when you are building or renovating. Ensure newly built or renovated rooms are well-ventilated during and after renovation to remove VOCs. Ideally, it is best not to use these rooms for one to two months after renovation – particularly for babies' rooms.


A warmer house is healthier for your family.

Mould multiplies fastest in damp, poorly insulated and heated, and badly ventilated houses.

In cold temperatures the moisture naturally in the air condenses on cold surfaces such as uninsulated walls, ceilings and windows. Condensation and humidity greater than 70 per cent are the perfect conditions for growing mould.

The Warmer Kiwis study by Motu Economic & Public Policy Research found every dollar spent on retrofitting insulation and improved heating resulted in about $4.40 return in health and wellbeing benefits (see the EECA (Energy Efficiency & Conservation Authority website).

Avoid unflued gas

Only use gas heaters which are flued (vented) to the outside, and make sure the range hood or extraction fan is on when you cook with gas. Burning gas releases moisture inside your home and also releases a range of pollutants that can be harmful to you and your family.

Heating your home has more information about unflued gas heaters.

Air filters

Air filters on any ventilation systems that bring air into the house are standard, and should be replaced or cleaned at intervals specified in the manufacturer’s literature. Special types of filters may be required:

  • 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 using a vacuum with a HEPA filter so they don't recirculate air with dirt, dust mites and pollutants
  • choosing non-toxic, biodegradable cleaning and maintenance products
  • 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-VOC 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 bacterial and fungal spores.

Eco Choice Aotearoa has lists of products that have been assessed as eco-friendly.

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: