Pollutants & Sources
What radioactive gas is found in many basements and poses a cancer risk?
Radon?
What is the main purpose of ventilation in HVAC systems?
To supply fresh air and remove pollutants
Name one common mechanical air-filter material.
Fiberglass or pleated media
When should ducts be cleaned?
When mold, pests, or excess dust are present
What is the recommended indoor relative-humidity range for homes?
40–60 percent
What type of smoke contains more than 40 carcinogenic compounds?
secondhand smoke
What does HRV stand for and what does it recover?
Heat Recovery Ventilator — recovers heat from exhaust air
What does HEPA stand for?
High Efficiency Particulate Air
What should you check before cleaning ducts for safety reasons?
Presence of asbestos
Explain why heated air feels dry.
As air heats, it expands and spreads out moisture
List two biological contaminants that can affect indoor air quality.
Dust mites, mold, bacteria, viruses
How is an ERV different from an HRV?
ERV transfers both heat and moisture; HRV transfers only heat
How does an ion generator help clean air?
It charges particles so they stick together and are easier to filter
Why should a vacuum exhaust to the outdoors during duct cleaning?
To prevent dust recirculation
Name one type of evaporative humidifier.
Bypass, plenum-mount, or pad-type
What building material can release formaldehyde (CH₂O)?
Plywood, particleboard, insulation, furniture finishes
Why is intake-location security important for outdoor air openings?
To prevent pollution or contaminant entry and improve safety
What type of light kills microorganisms in HVAC systems?
Ultraviolet (C or UV-C)
List two components that should be cleaned during duct maintenance.
Coils, drain pans, grilles, registers
What controls the operation of a humidifier based on moisture level?
Humidistat
What condition describes health problems caused by spending time in poorly ventilated buildings?
Sick Building Syndrome (SBS)
What standard sets the minimum ventilation requirements for acceptable indoor air quality?
ASHRAE 62.1
What substance in air purifiers removes odors and organic gases?
Activated charcoal
What organization’s standards should be followed for duct cleaning procedures?
National standards (NADCA guidelines)
List two common problems found during humidifier maintenance.
Water overflow, dust buildup, stuck float, low/high humidity