Given the size (a large dinner tray) and the dampness, this is beyond a DIY cleaning project. The wall cavity likely has more mold, and simply wiping the surface won’t solve the moisture source. Your children’s coughing is a significant indicator that spores are airborne.

After notifying management, engage a professional remediation company. They will identify the moisture source, contain the area to prevent spore spread during removal, and safely dispose of contaminated materials. In Dubai’s climate, hidden condensation behind furniture placed against external walls is common, but the dampness you feel suggests a more serious issue. A proper remediation includes fixing the water source and verifying with post-clearance testing that the space is safe. For health-related cases like yours, a company with its own microbiology lab can provide the specific identification and post-remediation verification that gives you confidence the issue is resolved.