How to Improve Your Home's Air Quality This Fall

How to Improve Your Home's Air Quality This Fall

Somewhere around the middle of October, most Vancouver and Portland homes close up for the season. Windows shut, doors stay shut, and the furnace or heat pump begins pushing the same air through the same ducts for the next five months. Whatever is in that air in October is largely what you are breathing in February.

That matters more here than in drier parts of the country. Northwest fall brings damp air, leaf mold, wood smoke from the first fires of the season, and a heating system that has been sitting untouched since spring. Put those together and indoor air quality stops being an abstract idea. It becomes the difference between a comfortable winter and five months of dust, stuffiness, and allergy symptoms nobody can quite explain.

Here is what actually moves the needle, in rough order of impact.

1. Start With the Filter, and Get the Rating Right

A fresh filter is the obvious first move. The part people get wrong is which one to buy.

Filters are rated by MERV, a scale that describes how small a particle the filter can catch. Higher numbers catch more. A MERV 11 to 13 filter traps pollen, mold spores, and most of the fine dust that a cheap fiberglass panel lets sail straight through into your blower and your living room.

The catch is that a filter too dense for your equipment restricts airflow. A restricted system runs hotter than designed, works harder for the same heat, and on a gas furnace can trip its high-limit switch and shut down entirely. Most residential systems in our area are comfortable somewhere in the MERV 8 to 11 range. Jumping to 13 or higher is a question worth asking the person who services your system rather than deciding in a hardware store aisle.

For most homes the practical answer is a pleated MERV 11, checked monthly once heating season is underway. Filters load up faster here than the printed 90 day interval suggests, because our long mild winter means the system runs far more hours than the label assumes.

2. Control the Moisture Before You Chase the Dust

Most national air quality advice is written for dry climates and tells you to add humidity. Here, the opposite is usually true.

Indoor humidity is best kept between 30 and 50 percent. Northwest homes in fall regularly drift above that, and damp indoor air is what mold, dust mites, and that faintly musty smell all depend on. The tell is condensation collecting on the inside of your windows on a cool morning. If you are seeing it regularly, your house is holding more moisture than it should.

The fixes are unglamorous and they work:

• Run bath fans longer. Twenty minutes after the shower ends, not just while you are in there. A fan that shuts off with the light switch is doing about half a job.
• Use the kitchen fan every time you cook. Especially anything simmering, which puts a surprising amount of water into the air.
• Check the crawlspace vapor barrier. A torn or missing barrier lets ground moisture rise into the house all winter. This is one of the most common causes of a damp home we find in older Vancouver and Portland properties.
• Do not let the dryer vent indoors. It happens more often than you would think, usually after someone disconnects a duct to move the machine.

3. Ventilate on Purpose

An older leaky house exchanges its air whether you want it to or not. A newer tight house does not, and that is exactly the point of building it that way, but it means fresh air has to be deliberate.

On a dry fall afternoon, open windows on opposite sides of the house for fifteen minutes. You lose very little heat and you flush out the accumulated cooking, cleaning, and off gassing from everything in the house. Do it before the wet season locks in and the opportunity gets rare.

If your home is newer and genuinely airtight, ask about a heat recovery ventilator. An HRV brings in outdoor air continuously while capturing most of the heat from the air it exhausts, which is the only way to get real ventilation through a Northwest winter without paying for it in heating costs.

4. Clean the Blower, Not Necessarily the Ducts

Duct cleaning gets marketed hard every fall and it is genuinely useful less often than the ads suggest. What almost always needs attention is closer to the equipment.

The blower wheel sits behind your filter and collects a felt like layer of dust over the years, particularly in homes that ran cheap filters or none at all. A dirty blower wheel moves less air, wastes energy, and sheds what it has collected into every room. The indoor coil collects the same buildup and, because it gets damp, can grow biological film that you will smell before you see.

Duct cleaning is worth doing when there is a specific reason for it: a remodel that filled the system with drywall dust, evidence of rodents, visible mold, or ducts that have never been touched in a house several decades old. Absent one of those, spend the money on maintenance instead.

5. Handle the Sources You Can Actually See

A few minutes of housekeeping in fall outperforms most equipment purchases:

• Clear leaves and needles away from your outdoor unit and any fresh air intake. Decomposing leaf litter is a mold source sitting right where your system breathes.
• Have the chimney or wood stove inspected before the first fire. Wood smoke is one of the largest fine particle sources in Northwest homes during winter.
• Vacuum with a HEPA equipped machine, and do it weekly once the windows close.
• Put a real doormat at every entrance. A large share of household dust walks in on shoes.
• Wash bedding in hot water through the season if anyone in the house has allergies. Dust mites thrive at exactly the humidity our winters provide.

6. Add Equipment Last, Not First

Air purifiers are the step most people want to start with. They work, but they work best after the basics are handled, and the right one depends on the problem.

A portable HEPA unit sized for the room is genuinely effective in a bedroom, where you spend eight hours a night. A whole home media filter cabinet, which uses a four to five inch filter instead of a one inch panel, gives you high filtration with far less airflow restriction than cramming a dense filter into a standard slot. Both are reasonable investments.

Be more skeptical of add on devices that promise to sanitize your air. Some have real evidence behind them, some do not, and a few generate ozone as a byproduct, which is itself a lung irritant. Ask what problem the device solves in your specific house before agreeing to it.

When to Service Your HVAC Before Winter

The second half of fall preparation is timing, and the timing is narrower than most people assume.

Book Between Mid September and the End of October

That window exists for practical reasons rather than tradition. Book inside it and you get a scheduled appointment, at a normal rate, with parts available if something turns up. Wait until the first genuinely cold week and you are calling the same companies as everyone else whose heat just failed, and routine maintenance moves behind every emergency call in the queue.

Parts availability is the part people underestimate. If a technician finds a failing inducer motor or a cracked heat exchanger in October, the repair gets ordered and scheduled while you are still comfortable. Find the same problem in January and you are choosing between space heaters and whatever can be sourced overnight.

Do Not Skip It Because You Have a Heat Pump

Heat pump owners often assume a spring air conditioning check covers them. It does not, because heating mode uses parts that cooling mode never touches: the reversing valve, the defrost control, and the backup electric heat strips. A system that cooled perfectly in July can still fail on its first defrost cycle in November.

Our damp climate makes this more than theoretical. Heat pumps here run all winter in wet air, and the defrost cycle is what keeps the outdoor coil from icing over. It is worth confirming it works before you need it.

Signs You Should Move It Up the List

• The system has not been professionally serviced in more than a year
• It sat completely unused from spring through summer
• You noticed anything unusual last winter that never got looked at
• The equipment is more than fifteen years old
• Anyone in the house has asthma or significant allergies

What the Visit Does for Your Air

Maintenance is usually sold on efficiency and lifespan, but several parts of it are directly about what you breathe.

The heat exchanger inspection is the one that matters most. A crack in a gas furnace heat exchanger can leak carbon monoxide into your living space, and there is no reliable way to check for it yourself. A technician also cleans the blower and coil, verifies the condensate line is draining rather than sitting as standing water near your equipment, and checks that duct connections in crawlspaces and attics are still sealed, so your system is not pulling crawlspace air into your bedrooms.

If you want the full pre winter checklist, we walk through it separately in our post on preparing your HVAC system for winter in the Pacific Northwest. This one is about the air itself and the calendar.

The Short Version

• Fresh pleated filter, MERV 8 to 11 for most homes, checked monthly all winter
• Keep humidity between 30 and 50 percent, and treat window condensation as a warning
• Run bath and kitchen fans longer than feels necessary
• Air the house out on dry fall days before the wet season sets in
• Clean the blower and coil before paying for duct cleaning
• Clear leaves from the outdoor unit and inspect the chimney before the first fire
• Book professional service between mid September and the end of October, heat pump included

Most of this list is free and takes an afternoon. The equipment side is not, which is exactly why it is worth doing while you still have the option to schedule it.

If it has been more than a year since your system was serviced, or your home never quite feels fresh once the windows close, our team works throughout Vancouver WA and the Portland metro area. Get in touch and we will take a look before the weather turns.