Ventilation and air filtration systems are key to achieving good indoor air quality compared to outdoor air. Heating, Ventilating, and Air Conditioning (HVAC) systems in buildings can control the flow of air, remove pollutants, and dilute indoor contaminants. These systems can create more healthy indoor spaces and reduce the impact of outdoor air on indoor air quality.
Ventilation: Ventilation systems help control the flow of outdoor air into indoor spaces. They also remove stale indoor air. Proper air flow is needed to dilute indoor pollutants, control humidity, and provide fresh air to occupants. These systems include:
- Natural ventilation: This relies on the natural flow of air through windows, doors, and other openings. It can be useful in areas with good outdoor air quality but is not so good in areas with high outdoor pollution levels.
- Mechanical ventilation: These systems use fans and ducts to actively move air in and out of the building. Mechanical ventilation provides more controlled air flow. This helps maintain good indoor air quality even when outdoor air quality is poor.
- Balanced ventilation: Balanced systems (e.g., energy and heat recovery ventilators), combine parts of supply and exhaust ventilation. These systems bring in fresh outdoor air and remove stale indoor air while cutting down energy loss.
Air filtration: Systems with air filters trap particles and contaminants on media. These systems can be distinctly helpful to reduce the impact of outdoor air pollution on indoor air quality. Some common systems include:
- HVAC filters: These filters are part of the building’s HVAC systems. They help remove particles from the air circulating through the system. Filters must be replaced and maintained to maintain good indoor air quality.
- Portable air purifiers: Stand-alone air purifiers with high-efficiency particulate air (HEPA) filters can be effective to remove particles, allergens, and some pollutants that are gases from indoor air. They can be especially helpful in rooms with poor air flow or during times of poor outdoor air quality.
- Activated carbon filters: These filters can help remove gaseous pollutants, such as volatile organic compounds (VOCs) and odors. The filters attract and hold pollutants onto the filter’s surface.
When ventilation and air filtration systems are combined, good indoor air quality can be maintained even when outdoor air quality is not good. Regular maintenance of these systems is key to ensure their effectiveness over time.