Dilution ventilation is not effective for surges of contaminants.

Dilution ventilation is not effective for surges of contaminants.

• A. It Is Not Effective for Surges of Contaminants
• B. It Is Effective for Surges of Contaminants
• C. It Has No Effect on Surges of Contaminants
• D. It Always Prevents Surges

Answer: (A)

Dilution ventilation lowers contaminant levels by mixing outdoor air with indoor air, and it works best when emissions are steady and ongoing. For a sudden surge of contaminants, the release can rise faster than the ventilation can dilute and transport it away. There’s a lag as fresh air mixes and plumes dilute, so the peak concentration may spike before dilution brings it down. Because of this immediate, short-term behavior, relying on dilution ventilation alone isn’t effective for handling bursts of contamination. To protect occupants during surges, you’d use local exhaust at the source, containment, or rapid isolation and other source-control measures in addition to general ventilation. That’s why the statement that dilution ventilation is not effective for surges of contaminants is correct.

Dilution ventilation lowers contaminant levels by mixing outdoor air with indoor air, and it works best when emissions are steady and ongoing. For a sudden surge of contaminants, the release can rise faster than the ventilation can dilute and transport it away. There’s a lag as fresh air mixes and plumes dilute, so the peak concentration may spike before dilution brings it down. Because of this immediate, short-term behavior, relying on dilution ventilation alone isn’t effective for handling bursts of contamination. To protect occupants during surges, you’d use local exhaust at the source, containment, or rapid isolation and other source-control measures in addition to general ventilation. That’s why the statement that dilution ventilation is not effective for surges of contaminants is correct.