Once the building has been assessed as safe to enter, an assessment of the property can be made.

An initial assessment is a report that can be used by remediators and insurance companies to plan how to return the property to pre-fire condition.  The assessment helps answer the following questions:

• What is the air quality on site like?
• Which items on site require remediation to return to pre-fire state?
• What should be removed? What can be cleaned?
• Is there risk from other non-fire contaminants (biological (mould/ bacteria) or asbestos)?

The assessment is performed by specialists that have a background in assessing the air quality risks as a consequence of fire damage. To do this they used highly specialised instruments.

Depending on the property and the extent of the fire, this can include:

• Scanning and mapping of VOCs (volatile organic compounds), particulate (dust) and gases using electronic instruments to assess affected areas.
• Itemising and assessment of materials for smoke and fire damage.
• Asbestos assessment and sampling. If asbestos materials have been damaged in the fire, we can conduct air, dust and soil sampling to assess contamination. If refurbishment work is required, a survey is necessary.

Smoke is a complex mixture of toxic gases and particles. The composition and amount of these toxic compounds depend on the materials involved and the fire circumstances.

The amount of energy given off by a material when it burns, known as its heat release rate (HRR), is a good predictor of how quickly smoke and harmful chemicals form. Among everyday furniture, sofas with upholstery burn particularly fast. When things like polyurethane foam and nylon carpets burn, they give off carbon monoxide and hydrogen cyanide. These substances pose a significant health risk if there's a fire.

Check out our article on the Auckland Convention Centre fire for more information.

After a fire, typical contaminants include PAHs (polycyclic aromatic hydrocarbons), benzene, isocyanates, dioxins and furans, aldehydes, inhalable fibers, and tiny particles. These combustion products can enter your body through breathing, skin contact, or swallowing. To make matters worse, many of these compounds are linked to causing cancer.

Toxins from a smoke and a fire will be absorbed into the building material and contents.  The hotter the temperature and the closer to the seat of the fire the greater the effect.  Rooms a good distance from the fire can be affected.  Off-gassing of these material can change with seasons.  As the ambient temperature rises, more can off gas.

Smoke rises so higher areas can be expected to be affected more than lower areas. Porous materials such as wood and soft furnishings have holes in them allowing material to be trapped.

Gases like nitrogen dioxide and carbon monoxide are expected to be flushed out over a shorter period. They would not be expected to be present after a week of good ventilation.

Do not enter the property until it is safe to do so.

Once you are able to enter, an assessment of the property should be made.  People making the assessment must be skilled in the chemistry of fires and what is affected and what is not.  They must also understand which material needs to be removed and what material can be cleaned. K2 Environmental can assist with this.

Some materials may be able to be cleaned, while others should be discarded. This will depend on the type of material, the exposure to smoke, the type of fire (such as wet or dry) and other factors like the value of the item.

In most cases, professional restoration companies should engaged so materials can be properly cleaned and de-odourised.

However, some things will not be able to be cleaned and no amount of cleaning, ozone treatment or fogging will restore the material to its pre-fire condition.

See Fire and Emergency NZ's advice on what to do after a fire for more information on how to deal with specific items.

After restoration has been completed, post-remediation testing can verify the house has returned to pre-fire conditions.

Post-remediation testing typically involves an in-depth assessment of the toxins present and how they compare against international good air quality standards. Some toxic compounds have been identified to off-gas for over two years after a fire. An in-depth analysis can determine if these are present and if they are likely to be a risk to health. Assessments consider people occupying the property for 24 hours in domestic situations.

Treatments of fire damaged properties vary as does the effectiveness. To ensure the occupants are not put at risk an in-depth assessment is required.

We are experienced with a wide range of testing and assessments that may apply after a fire. This includes:

• Asbestos assessments and sampling
• Mould and bacteria testing
• VOC (volatile organic compound) testing

If you are unsure of the level of contamination in an area, it is always advised to wear a properly fit-tested mask. Organic cartridge filters can remove harmful compounds and odour from your breathing zone.

If you are working in smoke or fire-damaged properties regularly, it is strongly advised to get your mask properly fit-tested to ensure it is working. If you can smell any smoke that is a sign that there still exists toxins in the property.

K2 Environmental offers a mask fit testing service to ensure you and your employees are protected.