Infiltration: Outdoor air can infiltrate through cracks and gaps around windows, doors, and other openings in the building envelope. This process is known as infiltration, and it can bring in pollutants such as particulate matter (PM), nitrogen dioxide (NO2), and volatile organic compounds (VOCs) from outside.
Mechanical ventilation: Many buildings use mechanical ventilation systems to supply fresh air and remove stale air. However, if the outdoor air is polluted, the ventilation system can bring in these pollutants and distribute them throughout the building. This is especially concerning for buildings with inadequate air filtration systems.
Attached garages: If you have an attached garage, pollutants from vehicles, such as carbon monoxide (CO), nitrogen oxides (NOx), and VOCs, can enter your home through the garage door and migrate into the living space.
Open windows and doors: During hot weather, people often open windows and doors to let in fresh air. However, this can also allow outdoor pollutants to enter the home. Keeping windows and doors closed during peak pollution hours can help reduce indoor air pollution.
Resuspension of particles: Outdoor particles can be tracked into the home on shoes, clothing, and pets, and can also be resuspended into the air from carpets, furniture, and other surfaces. These particles can contribute to indoor air pollution, especially if they contain harmful substances such as heavy metals or chemicals.
Chemical reactions: Outdoor pollutants can react with indoor chemicals to form new pollutants. For example, ozone (O3), which is a common outdoor pollutant, can react with indoor surfaces and furnishings to produce VOCs and formaldehyde. These secondary pollutants can further contribute to indoor air pollution.
Inadequate ventilation: Buildings with poor ventilation or inadequate airflow can trap outdoor pollutants indoors, leading to higher indoor air pollution levels. This is especially concerning for buildings without mechanical ventilation systems or with limited natural ventilation.
To mitigate the impact of outdoor pollution on indoor air quality, it's essential to maintain a tight building envelope, use high-quality air filters in ventilation systems, and minimize the entry of outdoor pollutants into the home. Additionally, regular cleaning and maintenance of indoor surfaces can help reduce the accumulation of pollutants and improve indoor air quality.
