Indoor Air Quality: How Your HVAC System Helps

You’re sitting inside on a hot day with the windows closed. Your kid starts sneezing. Your allergies kick in. You assume it’s pollen blowing in from outside, but the windows are shut.

The problem is inside your house. And your HVAC system is either making it better or making it worse.

Concerned about indoor air quality? Call 919-864-0824 to discuss air filtration options, or contact Salmon’s Heating and Air.

Most people don’t think of their AC system as an air quality tool. They think it just cools. But your HVAC system pulls air from your house, filters it, and circulates it back. That’s how you control what you’re breathing.

What’s Actually in Your Air

Indoor air contains more than temperature. It contains:

• Dust and dust mites — Dead skin cells, fibers, pet hair
• Pollen — Tracked inside on clothes, blown through vents, settling on surfaces
• Pet dander — Tiny skin flakes from dogs and cats
• Mold spores — From bathrooms, basements, or damp areas
• Bacteria and viruses — From people, pets, and surfaces
• VOCs — Volatile organic compounds from paint, cleaners, furniture, carpeting
• PM2.5 — Fine particulate matter from cooking, candles, outside air

Your filter catches some of this. But the type of filter matters a lot.

Filter Grades and What They Catch

HVAC filters are rated by MERV (Minimum Efficiency Reporting Value). Higher MERV = better filtration.

MERV 8 (Basic Filter):
Catches large particles: dust, pollen, pet hair. Misses small stuff like bacteria and mold spores. This is the minimum. If you have allergies or pets, this isn’t enough.

MERV 11-13 (Mid-Grade):
Catches dust, pollen, pet dander, mold spores, and some bacteria. Good for most households. If anyone in your family has allergies, start here.

MERV 16 (High-Grade):
Catches fine particles, bacteria, and viruses. Nearly as good as a HEPA filter. Moderately more expensive but effective if you’re serious about air quality.

HEPA Filters:
Hospital-grade filtration. Catches 99.97% of particles down to 0.3 microns. Requires a specialized system because they restrict airflow. The EPA lists HEPA filtration among the most effective air purification methods.

Real talk: Most people with allergies should use MERV 13. It provides excellent filtration and is only slightly more expensive than basic filters.

The Filter Replacement Reality

A better filter only works if you change it regularly.

• MERV 8-11: Change every 30 days during cooling/heating season
• MERV 13-16: Change every 30-45 days (they trap more so they clog faster)
• If you have pets: Change every 15-20 days
• If you have allergies: Change every 20-30 days

Most people buy high-quality filters and then forget to change them. A clogged filter is useless—it restricts airflow and forces your system to work harder.

Pro tip: Set a phone reminder. It takes 30 seconds to swap a filter.

Beyond the Filter: Other Air Quality Solutions

Your main filter does most of the work. But you can add more:

UV Light Purifiers

UV lights inside your ductwork kill bacteria and mold. Benefit: Reduced airborne bacteria, especially helpful if someone in your house is frequently sick. Installation is moderately priced.

HEPA Filter Systems

A secondary HEPA filter adds another layer. Benefit: Hospital-grade air. Probably overkill for most homes, but can be valuable for serious allergies. Installation is a significant investment.

Humidity Control

Excess humidity (above 55%) promotes mold and dust mites. Low humidity (below 30%) causes dry skin and respiratory irritation. A whole-house humidifier or dehumidifier keeps humidity between 35-55%, with options at various price points.

Ductwork Cleaning

Every 3-5 years, ducts accumulate dust, mold, and debris. Professional duct cleaning removes this buildup at a reasonable cost. It’s helpful if your family has allergies or asthma.

Fresh Air Intake

Sealed houses trap stale air and VOCs. A fresh air intake system brings outside air in and mixes it with your recirculated air. This helps if your house smells stale or you have chemical sensitivity. It’s a more significant investment. Salmon’s Heating and Air can help with ductwork and installation services to set this up properly.

Simple Changes That Actually Help

You don’t need expensive solutions. Start here:

1. Upgrade to MERV 11 or 13 filters — Inexpensive, change every 30 days. Impact: 80% of air quality improvement.
2. Change your filter on schedule — Set a phone reminder. A clogged filter defeats everything else.
3. Clean or vacuum your vents and registers monthly — Dust buildup blocks airflow and recirculates dust. Takes 5 minutes.
4. Keep humidity between 35-55% — Use an inexpensive humidity meter to check. Use a dehumidifier in summer if needed.
5. Seal air leaks around windows and doors — Outside air sneaks in. Caulk gaps and weatherstrip doors.
6. Reduce sources of pollution — Fewer scented candles, fewer harsh cleaners, good ventilation when cooking.

In Closing

Your HVAC system is your air quality tool. A good filter changed regularly catches dust, pollen, pet dander, mold, and bacteria. That’s 80% of the battle.

For the remaining 20%, consider humidity control and maybe UV lights if allergies are a problem. But start with the filter.

Take time this week to check your current filter. If it’s gray or brown instead of white, it’s clogged—change it now. Then set a reminder to change it monthly. You’ll breathe better and your family will be healthier.

Want to improve your indoor air quality? Call 919-864-0824 to discuss filter upgrades and air quality solutions, or contact Salmon’s Heating and Air. We serve Durham, Burlington, Hillsborough, Haw River, and Mebane.