Question

why do garages usually have low air quality?
they are outside.
chemicals are stored in garages.

Explanation:

Garages often store chemicals like paints, solvents, and car maintenance products. These chemicals can release volatile organic compounds (VOCs) and other pollutants into the air. Also, cars in garages (even when not running) can emit residual exhaust fumes. Poor ventilation in many garages (as they are often closed - off spaces) traps these pollutants, leading to low air quality. The option "They are outside" is incorrect as garages are usually attached to homes (not truly 'outside' in the sense of open - air environments) and even if detached, they are enclosed spaces.

Answer:

Chemicals are stored in garages.