How to Improve Indoor Air Quality in Winter
There’s something you probably haven’t thought much about: the air inside your home right now. During a Minnesota winter, especially in the Brainerd Lakes Area where temperatures demand that homes be tightly sealed from November through March, indoor air quality can be significantly worse than outdoor air. We’re talking 2 to 5 times worse, according to the EPA.
That might sound alarming, but it makes sense when you think about it. Your home is buttoned up all winter. You’re breathing the same air over and over. Combustion appliances, cooking, cleaning products, furniture off-gassing, pets, and moisture all contribute to what builds up inside. Without the natural ventilation that open windows provide, these pollutants concentrate.
The good news: there are practical, meaningful steps you can take to improve your indoor air quality, and most of them aren’t complicated or expensive.
Understand What’s in Your Winter Air
Before addressing the problem, it helps to know what you’re dealing with. Common winter indoor air pollutants include:
- Dust and particulates, from everyday activities, skin cells, fabric fibers, and pet dander
- Volatile Organic Compounds (VOCs), from furniture, flooring, cleaning products, paints, and personal care products
- Carbon monoxide, from combustion appliances (furnaces, water heaters, gas stoves) if not properly vented
- Carbon dioxide, from breathing; high CO₂ levels cause fatigue and difficulty concentrating
- Mold spores, thriving in areas of excess moisture
- Allergens, pet dander, dust mites, and cockroach allergens (common even in clean homes)
- Radon, a naturally occurring radioactive gas that seeps from soil; Minnesota has elevated radon levels compared to national averages
In winter, most of these are trapped inside with you at higher concentrations than they’d be in warmer months.
1. Change Your Furnace Filter Regularly
This is the single most impactful thing most homeowners can do for indoor air quality, and it also keeps the HVAC system running efficiently. Your furnace filter is the primary barrier between recirculating air and the stuff you don’t want to breathe.
Filter recommendations:
- Replace standard 1-inch filters every 30–90 days during heating season
- Choose filters with a MERV rating of 8–12 for meaningful particulate filtration without restricting airflow
- If allergies or asthma are concerns, consider a MERV 13 filter, these capture finer particles including some bacteria and viruses
- Don’t go too high on MERV for a standard system, MERV 16+ filters can restrict airflow and strain your furnace
A dirty, clogged filter not only fails to clean your air, it pushes contaminated air back through the system. Check your filter monthly in winter, not quarterly.
2. Address Humidity, The Minnesota Winter Problem
This one is specific to our climate and critically important. In the Brainerd Lakes Area, winter air is extremely dry, outdoor humidity is low, and heating that air further reduces its relative humidity. Many Minnesota homes hover at 10–20% relative humidity in January. The ideal range is 30–50%.
Effects of low humidity:
- Dry skin, chapped lips, irritated sinuses
- Increased susceptibility to respiratory infections (dry mucous membranes are less effective at trapping pathogens)
- Static electricity (the classic Minnesota winter shuffle)
- Damage to wood floors, furniture, and musical instruments
- Feeling colder at the same temperature (humid air feels warmer)
Solutions:
- Portable humidifiers can help in specific rooms but require daily maintenance (cleaning) to prevent mold and bacteria growth
- Whole-home humidifiers installed on your furnace are a much better long-term solution, they add moisture to the entire air distribution system automatically. This is what we typically recommend for Brainerd Lakes Area homes.
Be careful not to over-humidify. Humidity above 50% in winter creates its own problems, condensation on windows, mold growth in walls and crawlspaces, and dust mite proliferation. A hygrometer (humidity gauge) lets you monitor your levels; they cost $10–$20 at any hardware store.
3. Upgrade Your Filtration with an Air Purifier
Furnace filters handle particles in the air as they pass through the system. But air purifiers can address what filters miss, and can work on air in rooms that may not circulate through the system frequently.
Types of air purifiers:
- HEPA air purifiers (High-Efficiency Particulate Air): The gold standard for particle removal. True HEPA filters capture 99.97% of particles 0.3 microns and larger, including most allergens, dust, and many bacteria. Great for bedrooms and living spaces.
- Activated carbon filters: Excel at removing odors, VOCs, and gases that HEPA can’t capture. Often paired with HEPA in quality units.
- UV-C purifiers: Use ultraviolet light to deactivate bacteria and viruses. Effective when combined with HEPA filtration.
- Whole-home air purifiers: Installed in your ductwork, these treat air as it passes through the system. High-end options include electronic air cleaners and UV systems that address both particles and biological contaminants.
For allergy or asthma sufferers, whole-home systems represent the most comprehensive solution. For most households, a combination of quality furnace filtration and a portable HEPA purifier in bedrooms covers the bases well.
4. Ensure Proper Ventilation
In an airtight Minnesota home, fresh air doesn’t come in on its own, you have to provide it. There are several approaches:
Exhaust fans: Run your kitchen and bathroom exhaust fans regularly. They pull stale, humid air out and create slight negative pressure that draws fresh air in through small gaps. This simple habit makes a real difference.
Energy Recovery Ventilators (ERVs) and Heat Recovery Ventilators (HRVs): These devices exchange stale indoor air for fresh outdoor air while recovering most of the heat (or cool) from the outgoing air. An HRV can recover 70–80% of the heat from exhaust air, making fresh air ventilation energy-efficient even in Minnesota winters. If your home is well-sealed and you’re noticing stuffiness or condensation issues, an HRV or ERV is worth serious consideration.
Strategic window cracking: When outdoor temperatures are above 20°F and wind is calm, cracking a window briefly for 10–15 minutes provides meaningful ventilation without excessive heat loss. Even in winter, brief ventilation helps flush accumulated pollutants.
5. Test for Radon
This one often gets overlooked because radon is invisible, odorless, and tasteless. But Minnesota has significantly elevated radon levels, it’s estimated that 2 in 5 Minnesota homes have radon levels above the EPA action level of 4 pCi/L.
Radon is the second leading cause of lung cancer in the US after smoking. It’s produced by uranium decay in soil and rock and seeps into homes through foundation cracks and openings. In winter, with homes sealed and negative pressure pulling air in from the ground, radon concentrations can be at their highest.
Testing is easy and cheap. DIY radon test kits are available at hardware stores for $15–$30. If your levels are above 4 pCi/L, mitigation systems (sub-slab depressurization) are effective and relatively affordable, typically $800–$2,500 installed.
6. Reduce Pollution at the Source
Air purification is most effective when you also reduce what you’re purifying against:
- Use low-VOC or zero-VOC cleaning products, many conventional cleaners release significant VOCs
- Avoid synthetic air fresheners, they mask odors with VOCs. Use baking soda, activated charcoal, or good ventilation instead.
- Keep your combustion appliances properly maintained, a well-tuned furnace produces far less CO and particulates than a neglected one
- Don’t idle vehicles in attached garages, even briefly, exhaust can infiltrate the living space
- Vacuum regularly with a HEPA-filtered vacuum, standard vacuums often just redistribute dust
Breathe Better This Winter
Improving your home’s air quality doesn’t require a dramatic overhaul. Start with the basics, filter changes, humidity control, exhaust fans, and build from there. For Brainerd Lakes Area homeowners who want to take it further, a whole-home humidifier, HRV, or air purification system installed by Maverick’s Heating & Air can make a genuine, noticeable difference in how you feel at home all winter.
Contact us to discuss indoor air quality solutions for your home, we’re happy to help you breathe easier.