Indoor Air Quality: How Your Air Conditioner Affects Your Health

We spend up to 90% of our time indoors, and the quality of the air we breathe at home significantly impacts our health. Your air conditioner doesn't just control temperature—it influences humidity, filters particles, and circulates air throughout your living space. Understanding this relationship helps you create a healthier indoor environment for your family.

How Air Conditioners Affect Indoor Air Quality

Air conditioners interact with indoor air quality in several important ways, both positive and potentially negative.

The Positive Effects

• Filtration: Air passes through filters that capture dust, pollen, and other particles
• Humidity control: Removing excess moisture reduces mould growth and dust mites
• Circulation: Moving air prevents stagnant pockets where pollutants accumulate
• Exclusion: Running AC with closed windows keeps outdoor pollution and allergens outside
• Temperature regulation: Comfortable temperatures reduce heat stress and improve sleep

The Potential Negatives

• Poor maintenance: Dirty filters and coils can harbour and distribute mould, bacteria, and allergens
• Over-drying: Excessive use can make air too dry, irritating airways
• Recirculation: Without fresh air, indoor pollutants can accumulate
• Noise: Some units create sleep-disrupting noise levels

Understanding Air Filtration

Filtration is your AC's primary tool for improving air quality. Understanding how it works helps you maximise its benefits.

Standard AC Filters

Most residential air conditioners come with basic mesh filters designed primarily to protect the equipment, not optimise air quality. These filters:

• Capture larger particles (dust, lint, pet hair)
• Require regular cleaning (every 2-4 weeks)
• Don't capture fine particles, allergens, or pathogens
• Are sufficient for general use in healthy households

Advanced Filtration Options

Many modern air conditioners offer enhanced filtration:

• HEPA filters: Capture 99.97% of particles 0.3 microns and larger, including most allergens and some bacteria
• Activated carbon filters: Absorb odours, chemicals, and volatile organic compounds (VOCs)
• Plasma/ionisation: Generate charged particles that attach to airborne contaminants
• UV-C lights: Kill bacteria and viruses passing through the system
• Catechin filters: Feature anti-bacterial coatings that inhibit microbe growth

Humidity and Your Health

Air conditioning significantly impacts indoor humidity levels, which affects both comfort and health.

Why Humidity Matters

Ideal indoor humidity is between 40-60%. Outside this range, problems occur:

Too high humidity (above 60%):

• Promotes mould and mildew growth
• Increases dust mite populations
• Creates musty odours
• Makes temperatures feel hotter (reduced evaporative cooling from skin)
• Can trigger asthma and allergies

Too low humidity (below 40%):

• Dries out skin, eyes, and airways
• Increases susceptibility to respiratory infections
• Aggravates eczema and other skin conditions
• Creates static electricity
• Can worsen asthma symptoms

Managing Humidity with Your AC

Your air conditioner naturally dehumidifies as it cools—moisture condenses on the cold evaporator coil and drains away. To optimise humidity:

• Use "dry" mode: Most split systems have a dedicated dry/dehumidify mode that prioritises moisture removal
• Don't overcool: Running the AC extremely cold then turning it off creates humidity swings
• Size correctly: Oversized units cool quickly but don't run long enough to dehumidify properly
• Consider a separate dehumidifier: For very humid climates or specific rooms

Maintaining Clean Air

The key to healthy air from your AC is consistent maintenance. Neglected units become sources of contamination rather than solutions.

Critical Maintenance for Air Quality

• Clean filters regularly: Every 2-4 weeks during heavy use; monthly minimum
• Clean indoor unit: Wipe exterior monthly; professional coil cleaning annually
• Check drain line: Blocked drains create moisture problems and mould risks
• Inspect for mould: Look for black spots or musty smells—signs of mould growth
• Annual professional service: Technicians clean areas you can't access

Beyond Your AC: Comprehensive Air Quality

While your AC helps, it's not a complete air quality solution. Consider these complementary measures:

• Ventilation: Periodically open windows to introduce fresh air (when outdoor air quality is good)
• Source control: Reduce indoor pollutants (avoid smoking, use low-VOC products, control dust)
• Standalone air purifiers: For additional filtration in problem areas
• House plants: Some evidence suggests they help remove certain pollutants (though impact is modest)
• Regular cleaning: Vacuum with HEPA filters, dust surfaces, wash bedding frequently

Air Quality and Australian Conditions

Australian homes face specific air quality challenges that interact with air conditioning use.

Bushfire Smoke

During bushfire seasons, outdoor air quality can become hazardous. Your AC can help:

• Keep windows closed and run AC to filter indoor air
• Units with HEPA or plasma filtration are particularly effective
• Recirculation mode prevents drawing in smoky outdoor air
• Change/clean filters more frequently during smoke events

Tropical Humidity

Northern Australia's high humidity creates specific challenges:

• Mould growth risk is elevated—maintenance is critical
• Use "dry" mode liberally
• Consider units with enhanced dehumidification
• Ensure condensate drains properly

Dust in Dry Regions

Inland and western regions experience significant dust:

• Clean filters more frequently
• Check outdoor unit for dust accumulation
• Seal gaps around windows and doors to reduce dust entry

Choosing an AC for Better Air Quality

If air quality is a priority, consider these features when selecting a new unit:

• Advanced filtration: HEPA, plasma, or photocatalytic options
• Self-cleaning function: Automatically dries the evaporator to prevent mould
• Humidity control: Dedicated dehumidification modes
• Quiet operation: Especially for bedrooms (look for 19-24 dB rated units)
• Inverter technology: Runs more consistently, better humidity control

Creating a Healthier Indoor Environment

Your air conditioner is a powerful tool for improving indoor air quality when used correctly. The key principles are:

1. Maintain religiously: Clean filters, annual servicing, prompt attention to issues
2. Control humidity: Use dry modes in humid weather, don't over-cool
3. Consider upgrades: Enhanced filtration for allergy sufferers or poor outdoor air quality
4. Supplement wisely: Ventilate when appropriate, use additional purifiers if needed
5. Reduce sources: Address indoor pollution sources directly

By understanding and managing these factors, you can ensure your air conditioning system contributes to a healthier home environment for you and your family.

For maintenance best practices, see our complete AC maintenance guide.