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Arsenic and treated timber

Arsenic detected in Nelson South area

A report commissioned by the Council on air quality in the Nelson South area (Victory/Washington Valley/Hospital area) has detected high levels of arsenic.
Click here to download a copy of the report. (3.4MB PDF)

How much arsenic is in the air?

The average annual concentrations indicates that the New Zealand Ambient Air Quality Guideline for arsenic (5.5 ng m-3 annual average) is substantially exceeded every year in Nelson South, with the highest concentrations during winter (maximum around 90 ng m-3).

The arsenic was strongly associated with the solid fuel burning and is considered to be from the use of copper chrome arsenate (CCA)-treated timber as fuel for domestic fires.

How much would we have to have before we become sick?

People will have differing tolerance levels and more studies are required to answer this question.

Levels below the national guideline are considered to be safe for exposure over a life time. The Nelson report reveals elevated levels over winter periods. However, it is very easy to significantly reduce the risk by not burning CCA treated timber.

What happens when CCA treated wood is burned?

Poisonous chemicals are released into the air and affect people and the environment. Arsenic can also build up in the ash and be breathed in or contaminate the disposal area.

Is it safe to burn treated wood in an enclosed fireplace or wood burner?

No. It is likely that people burning treated timber might expose themselves to even higher levels of arsenic inside their homes as arsenic will be released directly from burning or when wood burners are loaded or cleaned.

Burning CCA treated timber in any fire is banned because releasing arsenic into the air is also harmful to other people and the environment.

What is CCA?

CCA treated wood has been treated with chrome, copper and arsenic. The arsenic is used to resist to rotting and decay.

How can I tell if wood has been treated with arsenic?

It can be difficult to tell. Most timber that is used outside is treated with arsenic. It can have a green stain, but sometimes this is difficult to see if the timber is old or weathered.

Most outdoor building timbers have been treated with arsenic.

cca treated wood june14

CCA treated pine off-cuts (H3.2)

Do not burn
CCA treated wood for outdoor use, such as fencing or decking, outdoor furniture or cladding.

Other wood products that release chemicals when burned include

  • Any wood product with a coating, such as melamine or formica
  • Painted, stained or varnished wood
  • MDF or custom wood, chip board or plywood (these contain glues and binding agents)

Do not collect wood off-cuts from building sites and - if in doubt, throw it out!

How do I dispose of off-cuts?

All treated, coated or manufactured wood products should be taken to the transfer station to be disposed of.

What timber can I burn?

The safest timber to use in your fireplace or BBQ is natural 100% untreated wood. Some building materials may be safe to burn. Ask your building supplies specialist
how the timber has been treated when you purchase it.

A reliable, safe source of wood is the Council’s Good Wood suppliers.