Black dust from AC causing cough: mold and who to call?« Back to Previous Page

This is most likely a combination of mould growth and fine particulate matter from degraded duct lining or insulation. The correlation between your symptoms and time spent in the room strongly indicates the AC system is the source. In Dubai's climate, with high humidity and year-round AC use, condensation inside ducts creates a perfect environment for mould if not thoroughly dried and treated.

For a problem this persistent, a standard duct cleaning is insufficient. You need a professional who specializes in indoor air quality diagnostics, not just cleaning. Look for a provider that uses a borescope inspection to see inside the ductwork and, crucially, offers surface and air sampling to be analysed by an accredited microbiology lab. This lab analysis is the only way to definitively identify the mould species and the concentration levels, which dictates the remediation protocol.

The black dust suggests it could be Stachybotrys, commonly called "black mould," which is associated with the symptoms you describe, though other types like Cladosporium can also appear dark. A proper fix may involve replacing contaminated insulation or sealing leaking ducts to prevent moisture intrusion, which is the root cause. Any reputable company should provide a detailed report with before-and-after lab results to verify the issue is resolved.