Smoke from forest fires is most likely to affect air quality over larger areas for many days when

Smoke from forest fires is most likely to affect air quality over larger areas for many days when

• A. A persistent atmospheric inversion exists in the region
• B. High wind speeds remove pollutants quickly
• C. Heavy rainfall occurs in the region
• D. High relative humidity improves dispersion

Answer: (A)

A stable layer of air that traps pollutants near the surface is the key idea. When an atmospheric inversion forms, the warmer air above acts like a lid, preventing the cooler, smoke-filled air from rising and mixing upward. With vertical mixing limited, the smoke stays concentrated close to the ground and is carried along by regional winds. If this inversion persists for many days, the same air mass keeps accumulating pollutants and spreads them over a wide area, causing poorer air quality across large regions for an extended period. Strong winds would dilute and move pollutants away more quickly rather than locking them in, so the impact wouldn’t linger in one area for days. Heavy rainfall would remove particles from the air, cleaning it rather than sustaining the pollution. High relative humidity doesn’t inherently improve dispersion in a way that would promote long-lasting, wide-area pollution; it can even affect particle behavior in other ways, but it doesn’t produce the persistent, broad-reaching effect that a lasting inversion does.

A stable layer of air that traps pollutants near the surface is the key idea. When an atmospheric inversion forms, the warmer air above acts like a lid, preventing the cooler, smoke-filled air from rising and mixing upward. With vertical mixing limited, the smoke stays concentrated close to the ground and is carried along by regional winds. If this inversion persists for many days, the same air mass keeps accumulating pollutants and spreads them over a wide area, causing poorer air quality across large regions for an extended period.

Strong winds would dilute and move pollutants away more quickly rather than locking them in, so the impact wouldn’t linger in one area for days. Heavy rainfall would remove particles from the air, cleaning it rather than sustaining the pollution. High relative humidity doesn’t inherently improve dispersion in a way that would promote long-lasting, wide-area pollution; it can even affect particle behavior in other ways, but it doesn’t produce the persistent, broad-reaching effect that a lasting inversion does.