A ventilation system keeps indoor air in buildings, factories, or other enclosed spaces fresh and safe by removing stale air, contaminants (dust, fumes, moisture, odors, vapors), and excess heat, while bringing in fresh outside air. In industrial or commercial settings, ventilation systems are critical for worker health and safety—helping prevent respiratory problems, controlling humidity to protect materials & equipment, averting buildup of volatile or flammable gases, and keeping working conditions within legal or comfort thresholds. They also play a big role in energy efficiency, as properly designed systems reduce heating or cooling losses and maintain more stable indoor climates.