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Indoor Air Quality Overview Reference

Reference Equipment Updated Jul 24, 2026 ยท HVAC · Cleaning

Why this matters

Indoor air quality (IAQ) affects customer's health + comfort. Many service calls relate to IAQ - allergies, asthma, mold, odors. The tech who understands IAQ basics + remediation can help customers significantly. This is the field card.

What IAQ involves

Air quality factors:

  • Particulate matter (dust, pollen, dander)
  • Volatile organic compounds (VOCs)
  • Carbon dioxide
  • Carbon monoxide
  • Mold spores
  • Humidity
  • Temperature

Health impacts:

  • Allergies
  • Asthma triggers
  • Respiratory irritation
  • Sometimes long-term concerns

Common IAQ issues

Particulates:

  • Dust
  • Pollen
  • Pet dander
  • Smoke
  • Construction debris

VOCs:

  • New furnishings (off-gassing)
  • Paint
  • Cleaning products
  • Building materials

Mold + mildew:

  • Damp areas
  • Health risk
  • Smell

Combustion gases:

  • CO (lethal)
  • NO2
  • Combustion equipment

Humidity:

  • Too high (mold)
  • Too low (dryness)

Stale air:

  • Inadequate ventilation
  • CO2 buildup
  • Comfort issues

IAQ assessment

Customer reports:

  • Allergies worse at home
  • Headaches
  • Fatigue
  • Respiratory issues
  • Smells / odors

Investigate:

  • Sources
  • Equipment
  • Ventilation
  • Identify root cause

Testing options

Particulate counter:

  • Counts particles per volume
  • Identifies high particulate
  • Sometimes filterable; sometimes not

CO2 monitor:

  • Ventilation indicator
  • Above 1,000 ppm = inadequate ventilation
  • 400-600 ppm = good

Humidity / temp:

  • Hygrometer
  • Comfort range 30-50% RH
  • Above 60% mold risk

CO detector:

  • Safety device (mandatory)
  • Diagnostic during HVAC service

VOC meter (specialty):

  • Total VOCs
  • Sometimes specific gases
  • Less common

Mold testing (specialty):

  • Air sample to lab
  • Spore identification
  • Use specialist

Common IAQ improvements

Source reduction:

  • Remove pollutant source
  • Most effective
  • Sometimes simple

Filtration:

  • Equipment upgrade
  • Per filtration article
  • Higher MERV

Ventilation:

  • Mechanical OR natural
  • Fresh air introduction
  • Sometimes ERV / HRV

Humidity control:

  • Whole-house humidifier / dehumidifier
  • Per humidity article

UV light (HVAC):

  • Coil sterilization
  • Air-stream UV
  • Per UV article

Air purifiers (standalone):

  • Single-room
  • HEPA filtration
  • Optional add-on

Source identification

Trace customer's symptoms to source:

At home (symptoms worse):

  • Indoor source
  • Investigate

Better away from home:

  • Indoor IAQ issue likely
  • Identify pollutant

Worse during specific activity:

  • Cooking (range hood inadequate)
  • Cleaning (chemical sensitivity)
  • New furniture / paint (off-gassing)

Seasonal patterns:

  • Allergens (pollen)
  • Heating season (combustion)
  • Cooling season (mold)

Customer's health considerations

Family member with:

  • Allergies
  • Asthma
  • Respiratory disease
  • Multiple chemical sensitivity

Higher IAQ standards needed:

  • More filtration
  • Source reduction
  • Sometimes specialist consultation

Common HVAC IAQ improvements

Filter upgrade:

  • Higher MERV (11-13)
  • More frequent change
  • Significant improvement

UV light:

  • Coil sterilization
  • Reduces mold
  • Standard add-on

Duct cleaning (sometimes):

  • Heavy buildup
  • Specialty service
  • Customer's preference

Whole-house air cleaner:

  • HEPA OR similar
  • Equipment investment
  • Significant filtration

Customer's mold situation

Visible mold:

  • Find source (moisture)
  • Address moisture
  • Remediate mold

Small (less than 10 sq ft):

  • Customer can DIY (with caution)
  • N95 mask + gloves
  • Bleach OR specialty product

Larger:

  • Professional remediation
  • Specialty contractor
  • Don't disturb until properly equipped

Customer's allergy customer

Common improvements:

  • Filter upgrade
  • HEPA whole-house OR room
  • Duct cleaning (sometimes)
  • Reduce pet dander (cleaning)
  • Humidity control

Customer may also need:

  • Medical advice (allergist)
  • Lifestyle modifications
  • Air purifiers

Common service request

Customer with allergies / asthma:

  • "Can my HVAC help?"
  • "What can I do for IAQ?"
  • "Should I clean my ducts?"

Recommend:

  • Filter upgrade first
  • Source reduction (pet dander, etc.)
  • Humidity control
  • Sometimes equipment upgrade

Duct cleaning controversy

Effectiveness varies:

  • EPA: not routinely recommended
  • Sometimes beneficial (visible mold, rodent, major contamination)
  • Sometimes minimal benefit

Customer's situation:

  • Heavy buildup visible = consider
  • New construction debris = consider
  • Routine = often not needed

Customer education

For each customer:

  • IAQ basics
  • What you observe
  • Recommendations
  • Customer's choices

Specific scenarios

Customer's child with asthma:

  • IAQ priority
  • Multiple improvements
  • Discuss with allergist sometimes

Customer's "musty smell" reported:

  • Mold likely
  • Investigate sources
  • Address

Customer's new home off-gassing:

  • Ventilation increased
  • Time (off-gassing reduces)
  • Air purifier

Customer's pet allergies:

  • Filter upgrade
  • Regular cleaning
  • HEPA in problem rooms

Combustion equipment IAQ

Gas equipment:

  • CO testing
  • Combustion analysis
  • Vent integrity

Wood-burning:

  • Particulate
  • Cleaning frequency
  • Air sealing

Cooking:

  • Range hood essential
  • Vented outside
  • Customer education

Outdoor air quality impact

Customer's indoor affected by:

  • Local air quality
  • Pollen seasons
  • Smoke (wildfires)
  • Industrial nearby

Limited control:

  • Filtration helps
  • Time-of-day windows
  • Sometimes air sealed

Ventilation balance

Too little ventilation:

  • Pollutants accumulate
  • CO2 builds
  • Stale air

Too much ventilation:

  • Energy loss
  • Outdoor pollutants enter
  • Sometimes humidity issues

Right amount:

  • Per ASHRAE 62.2
  • Modern tight homes need mechanical

ERV / HRV systems

Energy / Heat Recovery Ventilator:

  • Fresh air in
  • Stale air out
  • Heat exchange between
  • Energy efficient

For tight homes:

  • Required code sometimes
  • IAQ benefit significant
  • Capital investment

Smart sensors

IAQ monitors (consumer):

  • CO2
  • VOC
  • Particulate
  • Sometimes mold
  • Customer awareness

Cost vs benefit:

  • Customer's interest
  • Sometimes diagnostic value
  • Customer's choice

When to refer specialist

For:

  • Comprehensive IAQ audit
  • Mold remediation (large)
  • Asbestos / lead
  • Severe symptoms
  • Sensitive customer

Specialists:

  • IAQ consultant
  • Mold remediation
  • HVAC IAQ specialist
  • Sometimes medical

Customer's home age impact

Newer construction:

  • Tighter (better insulation)
  • More mechanical ventilation needed
  • Off-gassing common (new materials)

Older homes:

  • Leakier (more natural ventilation)
  • Old materials sometimes hazard (asbestos, lead)
  • Different IAQ approach

Cross-trade IAQ observations

References

  • EPA Indoor Air Quality resources
  • ASHRAE 62.2 (Ventilation Indoor Air Quality)
  • ASHRAE 55 (Thermal Environmental Conditions)
  • AAFA (Asthma + Allergy Foundation)
  • Manuall internal: Indoor Air Quality Testing, Common HVAC Add-Ons

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