Abstract
This 24-month longitudinal study tracked mould growth patterns in 180 Singapore residential properties across multiple monsoon cycles. Northeast monsoon (Nov-Mar) showed 280% increase in new mould cases compared to inter-monsoon periods. Properties without dehumidification showed 4.2x higher mould incidence during peak monsoon months.
Seasonal Patterns
| Season | Period | Avg. Humidity | Mould Index* |
|---|---|---|---|
| NE Monsoon | Nov - Mar | 87% | 280 |
| Inter-monsoon | Apr - May | 82% | 120 |
| SW Monsoon | Jun - Sep | 79% | 100 |
| Inter-monsoon | Oct | 83% | 140 |
*Mould Index: Baseline of 100 during SW Monsoon
Key Findings
- Peak Risk Period: December-January (highest rainfall + humidity)
- Most Affected: Ground to 5th floor units (42% higher incidence)
- Property Type: HDB corner units showed 65% higher mould rates
- Dehumidification Impact: 76% reduction in mould growth with active humidity control
High-Risk Factors During Monsoon
- Windows left open during rain (direct moisture ingress)
- Wet laundry dried indoors without ventilation
- Infrequent AC use allowing humidity buildup
- Poor bathroom ventilation after showers
Monsoon Season Recommendations
- Run dehumidifier 8-12 hours daily during NE monsoon
- Keep windows closed during and after rain
- Increase AC runtime or set to dehumidify mode
- Check for water ingress around windows and doors
- Dry laundry outdoors or use dryer during monsoon
- Schedule professional inspection before November