We assessed the prevalence of potential health hazards to intervention staff and cannabis growers in Belgian indoor cannabis plantations. Surface mold swab samples were taken at 16 Belgian indoor plantations contained mostly Penicillium sp. and Aspergillus sp. However, their precise health impact on intervention staff and illicit growers is unclear as no molds spore concentrations were measured. Atmospheric gas monitoring in the studied cannabis plantations did not reveal dangerous toxic substances. Health symptoms were reported by 60% of 221 surveyed police, but could not be linked to specific plantation characteristics. We conclude that Belgian indoor cannabis plantations pose a potential health threat to growers and intervention staff. AS there are currently no clear safety guidelines for seizure and dismantling of Belgian indoor cannabis plantations, we recommend first responders to follow strict safety rules when entering the growth rooms, which include wearing appropriate personal protective equipment.