One disadvantage of the dilution ventilation system is its inability to provide clean, safe air to breathe when the outdoor air is more polluted than indoor air or when the ventilation system is polluted. After all, this particular system does not remove all the contaminants from the air.
Additionally, a dilution ventilation system tends to be slow to respond to sudden acute exposure to contaminants. It is important to note that a dilution ventilation system can hardly extract metal fumes, vapour, dust, and other gases. Finally, it can be ineffective in regulating temperature, thereby creating comfort issues.
The local exhaust, on the other hand, can be problematic when there are numerous contaminant sources.