HVAC systems can pose a number of risks to both the building and its occupants. Poorly maintained systems can lead to the spread of airborne contaminants, such as mold, bacteria, and viruses, which can cause health problems. Additionally, HVAC systems can be a source of carbon monoxide poisoning if not properly maintained. Improperly installed systems can also lead to the release of hazardous gases, such as carbon dioxide and nitrogen dioxide, which can cause respiratory problems. Finally, HVAC systems can be a source of fire hazards if not properly maintained. Poorly maintained systems can lead to the accumulation of dust and debris, which can create a fire hazard.