Best HVAC Setup for Allergies & Asthma: Air Quality Guide

The Indoor Air Quality Problem

The EPA estimates indoor air can be 2-5 times more polluted than outdoor air. For allergy and asthma sufferers, this is especially problematic since we spend 90% of our time indoors.

Your HVAC system circulates air throughout your home constantly - making it either part of the problem or part of the solution.

Understanding Airborne Allergens

Common Indoor Allergens

• Dust mites: Microscopic organisms in bedding, carpets, upholstery
• Pet dander: Tiny skin flakes from cats, dogs, birds
• Mold spores: From damp areas, spread through air
• Pollen: Enters through open windows and doors
• Bacteria/viruses: Circulate through HVAC system

Particle Sizes

• Dust mite allergens: 10-40 microns
• Mold spores: 3-40 microns
• Pollen: 10-100 microns
• Pet dander: 2.5-10 microns
• Bacteria: 0.3-10 microns
• Viruses: 0.02-0.3 microns

Why This Matters: Different filtration captures different particle sizes.

Step 1: Upgrade Your Air Filter

Understanding MERV Ratings

MERV (Minimum Efficiency Reporting Value) indicates filter effectiveness:

MERVCapturesBest For

1-4Large particles onlyBasic protection 5-8Dust, lint, pollenMinimal allergies 9-12Small particles, moldModerate allergies 13-16Bacteria, smokeSevere allergies 17-20Viruses, ultrafineMedical settings

Our Recommendation for Allergy Sufferers

MERV 11-13 provides excellent filtration without straining your system.

Important: Higher MERV isn't always better. Filters above MERV 13 can restrict airflow in residential systems not designed for them.

Filter Change Schedule

For allergy sufferers:

• Check monthly
• Replace every 1-2 months (not 3)
• During high pollen seasons, replace more frequently

Step 2: Consider Air Purification

Types of Air Purification

1. HEPA Filtration (Bypass Systems)

• 99.97% effective at 0.3 microns
• Installed in ductwork
• Doesn't strain main system
• Cost: $800-1,500 installed

2. UV Light Systems (UV-C)

• Kills bacteria, viruses, mold
• Installed near evaporator coil
• Doesn't filter particles
• Cost: $500-1,200 installed

3. Ionizers/Plasma Systems

• Charges particles to clump together
• Easier for filter to catch
• Some produce small amounts of ozone
• Cost: $800-2,000 installed

4. PCO (Photocatalytic Oxidation)

• Breaks down VOCs and odors
• Combines with UV light
• Good for chemical sensitivities
• Cost: $700-1,500 installed

Best Combinations

• Allergies: HEPA + standard filtration
• Asthma: HEPA + UV light
• Multiple sensitivities: HEPA + PCO

Step 3: Control Humidity

Why Humidity Matters

• Too High (above 50%): Promotes dust mites, mold growth
• Too Low (below 30%): Dries airways, increases irritation
• Ideal Range: 35-50%

Solutions

For High Humidity:

• Whole-house dehumidifier ($1,500-3,000)
• Ensure AC is properly sized
• Fix any moisture sources

For Low Humidity:

• Whole-house humidifier ($400-1,000)
• Important in heating season

Step 4: Ensure Proper Ventilation

The Dilemma

Sealing your home for efficiency can trap pollutants inside. You need fresh air without bringing in outdoor allergens.

Solutions

1. ERV (Energy Recovery Ventilator)

• Exchanges indoor/outdoor air
• Filters incoming air
• Recovers energy from exhaust
• Cost: $1,500-3,500 installed

2. HRV (Heat Recovery Ventilator)

• Similar to ERV
• Better for colder climates
• Cost: $1,500-3,500 installed

3. Smart Ventilation Controls

• Brings in fresh air when pollen counts are low
• Integrates with air quality monitors
• Cost: $200-500 add-on

Step 5: Maintain Clean Ductwork

When Duct Cleaning Helps

• Visible mold growth
• After major renovation
• Rodent infestation evidence
• Previous owner had pets (if you're allergic)

Duct Sealing

Often more important than cleaning:

• Prevents unfiltered air from entering
• Stops allergens from attic/crawlspace
• Improves overall air quality
• Cost: $1,000-2,500

The Complete Allergy-Friendly HVAC Setup

Budget-Conscious Approach (~$300-500)

1. Upgrade to MERV 11-13 filters 2. Change filters monthly 3. Use exhaust fans in bathrooms/kitchen 4. Vacuum with HEPA vacuum weekly

Moderate Investment (~$1,500-3,000)

Add to above: 1. UV light system 2. Whole-house dehumidifier or humidifier 3. Annual duct inspection/sealing

Maximum Protection (~$4,000-8,000)

Add to above: 1. HEPA bypass filtration 2. ERV/HRV for fresh air 3. Smart air quality monitoring

Bay Area-Specific Considerations

Pollen Seasons

• Trees: February-May (heaviest March-April)
• Grasses: April-July
• Weeds: August-October

Strategy: Run HVAC fan continuously during peak hours with high-MERV filter.

Fog Belt Considerations

San Francisco, Daly City, Pacifica:

• Higher humidity = mold concerns
• Dehumidification more important than humidification

Fire Season Smoke

During wildfire season:

• Upgrade to MERV 13 temporarily
• Run fan continuously
• Consider portable HEPA for sleeping areas

Common Mistakes to Avoid

1. Using HEPA filters in standard systems: Can damage equipment 2. Ignoring humidity: As important as filtration 3. Never changing filters: Clogged filters are useless 4. Closing vents: Causes pressure problems, can increase dust 5. Ignoring mold sources: Filtration won't fix root cause

Our Recommendation

For most allergy/asthma sufferers, start with: 1. MERV 11-13 filter (change monthly) 2. UV light system (kills biologicals) 3. Proper humidity control

This combination addresses 80% of indoor air quality issues at reasonable cost.