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In general, MGO boards are considered very safe to use and are often marketed as a healthier and more environmentally friendly alternative to traditional building materials like drywall and plywood. Their safety comes from their core composition and performance characteristics.

1. Non-Toxic and Chemical-Free

• Natural Ingredients: MGO boards are made from naturally occurring mineral components, primarily magnesium oxide and other minerals like perlite. High-quality MGO boards do not contain harmful chemicals.
• No Formaldehyde or Asbestos: Unlike some older building materials or treated wood products, MGO boards are free of toxic substances like formaldehyde, asbestos, and crystalline silica. This makes them safer for both the installers and the occupants of the building.
• No VOCs: MGO boards do not off-gas volatile organic compounds (VOCs), which can contribute to poor indoor air quality and cause health issues like respiratory irritation and headaches.

2. Safety in a Fire

• Non-Combustible: MGO boards are non-combustible and have a very high fire rating (often rated A1). This means they do not catch fire or contribute fuel to a fire.
• No Toxic Fumes: A major safety advantage of MGO boards is that they do not emit toxic smoke or fumes when exposed to high heat. This is a significant improvement over materials like plywood, which can release dangerous gases when burned, and contributes to a safer evacuation path during a fire.

3. Resistance to Mold and Pests

• Moisture and Mold Resistance: Because the boards are made from inorganic materials, they do not provide a food source for mold, mildew, or fungus. This makes them an excellent choice for moisture-prone areas and for maintaining healthy indoor air quality.
• Pest-Proof: MGO’s inorganic composition also makes it impervious to pests like termites and carpenter ants.

Important Safety Consideration: The “Weeping” Issue

While MGO boards are generally very safe, there is one important issue to be aware of, which is tied to their specific chemical makeup.

• Magnesium Chloride (MgCl₂): Some early or lower-quality MGO boards use magnesium chloride as a binding agent. In high-humidity environments, magnesium chloride is hygroscopic, meaning it absorbs moisture from the air. This can cause the boards to “weep” or “cry,” releasing a salty, corrosive liquid onto the surface. This liquid can cause severe corrosion of metal fasteners, steel studs, and even aluminum, potentially compromising the structural integrity of the assembly over time.
• Magnesium Sulfate (MgSO₄): To address this, many modern, high-quality MGO boards use a different binder, magnesium sulfate. This formulation is not hygroscopic, so it eliminates the risk of weeping and corrosion, making it a much safer and more reliable choice, especially for projects in humid climates.

Conclusion:

MGO boards are a very safe building material due to their non-toxic, non-combustible, and mold-resistant properties. The primary safety concern is related to the specific binder used. To ensure safety, it is critical to source high-quality MGO boards from a reputable manufacturer and confirm that they are a magnesium sulfate-based formulation rather than a magnesium chloride-based one, particularly for applications in humid or exterior environments.