Air Quality

Managing Seasonal Allergies Through Your HVAC System

How to configure your HVAC system to reduce seasonal allergy symptoms throughout the year.

6 min read
Published: February 28, 2025
Updated: December 9, 2025

Each season brings different allergens. Here is how to adjust your HVAC strategy throughout the year.

Spring Allergies

Primary Allergens - Tree pollen (oak, birch, cedar) - Early grass pollen - Mold from winter moisture

HVAC Strategies - Upgrade to MERV 11+ filter - Change filter more frequently - Run fan to continuously filter - Keep windows closed on high pollen days

Bay Area Spring Notes - Tree pollen peaks February-May - Check daily pollen counts - Afternoon typically has highest levels

Summer Allergies

Primary Allergens - Grass pollen - Weed pollen - Mold spores - Dust mites (thrive in humidity)

HVAC Strategies - Maintain good filtration - Control humidity with AC - Consider dehumidifier if needed - Keep home sealed on bad air days

Bay Area Summer Notes - Grass pollen peaks May-July - Fire season can bring smoke - Air quality varies significantly

Fall Allergies

Primary Allergens - Ragweed and weed pollen - Mold from fallen leaves - Dust mites (indoor time increases)

HVAC Strategies - Clean ducts if not done recently - Fresh filter for heating season - Address any mold issues before winter - Consider air purifier for problem rooms

Bay Area Fall Notes - Weed pollen peaks August-October - Fire season continues - Monitor air quality alerts

Winter Allergies

Primary Allergens - Dust mites - Pet dander (more indoor time) - Mold - Indoor pollutants

HVAC Strategies - Maintain proper humidity (30-50%) - Continue regular filter changes - Use exhaust fans to control moisture - Consider whole-house humidifier if too dry

Bay Area Winter Notes - Mold increases with rain - Indoor allergens become primary concern - Heating can dry air excessively

Year-Round Strategies

Filtration - Minimum MERV 11 for allergies - MERV 13 for severe allergies - Change filters regularly - Consider whole-house air cleaner

Humidity Control - Keep between 30-50% - Too high: Dust mites and mold thrive - Too low: Respiratory irritation

Cleaning - Regular vacuuming with HEPA - Dust with damp cloth - Wash bedding in hot water weekly

Air Purifiers - HEPA purifiers for bedrooms - Especially during peak seasons - Size appropriately for room

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