An evaluation of strategies to reduce transport of pollutants from garages to homes

Five houses with attached garages were tested for contaminant transport into the living space. Sulphur hexafluoride tracer gas was intentionally released periodically in the garage, and concentrations were measured in air samples taken from various points within the living space, garage, and ancillary spaces. Progressive interventions, including passive/mechanical ventilation, and air/duct sealing were implemented to evaluate their impact on contaminant transport. Quantification of the contaminant transport and the effectiveness of the interventions were evaluated using the ratio of maximum sulphur hexafluoride concentration detected in the living space relative to the garage. Air sealing was effective only in some cases, and appears to be most applicable for sites without HVAC equipment located in the garage. Mechanical exhaust ventilation was effective to some degree at all sites, and was the only reliable method at sites with HVAC equipment in the garage. Although no interventions completely eliminated the transport of tracer gas into the living space, continuous mechanical exhaust ventilation was able to consistently reduce concentrations in the living space. The largest evaluated exhaust flow rate (290 CFM, 8.2 m³/min) resulted in living space concentrations less than 1% of that reached in the garage, and the smallest evaluated flow rate (50 CFM, 1.4 m³/min) reduced it to that level in 3 of the 5 houses.