Which of the following is a common indicator of mould presence in indoor environments?

Visible water stains are a common indicator of mould presence in indoor environments because they signal areas where moisture has accumulated. Mould typically thrives in damp conditions, and water stains can signify previous or ongoing water intrusion from leaks, condensation, or high humidity. These stains often appear on ceilings, walls, or floors and can indicate a problem that may lead to mould growth if not addressed.

Identifying and addressing the source of water stains is crucial for preventing mould proliferation, as mould spores can pose health risks and structural issues if the dampness is allowed to persist. Effective mould management includes inspecting areas with water stains for current moisture problems and addressing any underlying issues, such as plumbing leaks or inadequate ventilation.