Category 2 Smoke is defined by which ventilation rate range and burn times?

Category 2 Smoke is defined by which ventilation rate range and burn times?

• A. Ventilation Rate 17,250–34,499; 0900–1600 EST
• B. No burning allowed at this category
• C. Ventilation Rate 34,500–51,749; 0900–1700 EST
• D. Ventilation Rate 51,750–68,999; Daytime all hours

Answer: (A)

Category 2 Smoke is about selecting a middle-ground ventilation rate that allows enough air movement to disperse smoke while keeping burn timing within a daylight window when dispersion is generally favorable. The chosen range, 17,250–34,499, sits in the lower-middle portion of the ventilation scale, which corresponds to moderate smoke production that can be managed with a mid-morning to mid-afternoon burn window. The burn times from 0900 to 1600 EST align with typical daytime mixing conditions, avoiding the poorer dispersion often seen in early morning inversions or late afternoon stagnation. The other options either imply no burning at all, or use higher ventilation rates with longer or all-day windows, which would lead to more extensive smoke and fall outside Category 2’s defined, moderate conditions.

Category 2 Smoke is about selecting a middle-ground ventilation rate that allows enough air movement to disperse smoke while keeping burn timing within a daylight window when dispersion is generally favorable. The chosen range, 17,250–34,499, sits in the lower-middle portion of the ventilation scale, which corresponds to moderate smoke production that can be managed with a mid-morning to mid-afternoon burn window. The burn times from 0900 to 1600 EST align with typical daytime mixing conditions, avoiding the poorer dispersion often seen in early morning inversions or late afternoon stagnation.

The other options either imply no burning at all, or use higher ventilation rates with longer or all-day windows, which would lead to more extensive smoke and fall outside Category 2’s defined, moderate conditions.