Mould Hazard Classes Some countries have adopted a mold hazard class system to place molds in different categories based on their health risks. They are broken into Mould Hazard classes A, B and C: Mould Hazard Class List Mould Hazard Class A:Moulds in this group are either directly hazardous to health due to risk of infection or creation of toxins. They should … [Read more...] about Mould Hazard Classes