• Pressure treated wood is chemically treated in order to withstand weather, fungal decay and insects. Applications include decking, fencing, or any outdoor wood-based projects. 1 There are two main kinds of pressure treated wood: Copper Azole pressure treated and Alkaline Copper and Quaternary Ammonium (ACQ) pressure treated. 1, 4, 5


  • The pressure treatment process can be applied to a variety of wood types but is generally used on softwoods and most commonly Southern Yellow Pine. 3 Common chemicals used in the treatment process are: Alkaline Copper Quaternary, Copper Azole, Sodium Borate, and Micronized Copper Quaternary. 3


  • Sourcing of lumber may lead to deforestation in cases of unsustainable forest management. Mining for minerals such as copper may lead to water system contamination and/or habitat destruction. Small amounts of fungicides are added to pressure treated wood to prevent decay and may be detrimental to local ecosystems and waterways. 4

Human Health

  • Chemicals used to treat pressure treated wood contain known carcinogens and may cause reproductive harm such as birth defects. 2 Chemicals used in Copper Azole pressure treated wood are classified by OSHA as hazardous. 4


Safe Use and Exposure

  • Cut and sand outdoors whenever possible. If indoors, ensure proper ventilation and wear respirator. Dust may become combustible at high concentrations. Keep away from any sources of ignition.4 Wear chemical resistant gloves. 4

Proper disposal

  • Banned in all shops. Dispose of in dumpster.

Safe Alternatives

  • ACQ pressure treated wood has a lower rate of toxicity than Copper Azole but still contains many harmful chemicals. Cedar, however, can be used as an alternative due to the preservative qualities of its natural oils. With a treatment of linseed oil, cedar is appropriate for outdoor applications. 7


  1. “How to Choose Pressure Treated Wood”, Home Depot,
  2. “What is California Proposition 65”, Home Depot,
  3. “Your Guide to Working With Pressure-Treated Lumber”, Popular Mechanics,
  4. Copper Azole MSDS,
  5. ACQ Pressure Treated Wood MSDS,
  6. “Golden Lumber: Southern Yellow Pine”, North Crest Forest Products,
  7. “Alternatives to Pressure Treated Wood ( Outdoor Lumber)”, Chasing Green,