When winter arrives and we seal up our homes against the cold, indoor air quality often suffers. Homes in New Jersey are closed up tight to keep heat in, which means pollutants can accumulate and humidity levels drop. Stale, dry indoor air isn’t just uncomfortable – it can also aggravate allergies, spread illnesses more easily, and affect your health. Fortunately, by paying attention to a few key factors – including filters, humidity, and HVAC maintenance – you can keep your indoor air healthy throughout the winter.
Filter First: Keep Your Air Clean
Your furnace or heat pump’s air filter is the first line of defense for indoor air quality (IAQ). In winter, the heating system runs frequently, so the filter is constantly capturing dust, pet dander, pollen, and other particulates. Check and replace your HVAC filters regularly (about every 30-90 days) during winter. A clean filter not only protects your equipment, but it also significantly improves the air you breathe by removing airborne particles.
Consider upgrading the filter if you haven’t already done so. Standard fiberglass filters are pretty flimsy (capture only larger dust). High-quality pleated filters with a MERV rating around 11-13 can trap much finer particles, including mold spores, dust mite debris, and even some bacteria. For most home systems, MERV 11-12 is a good balance of filtration and airflow. Note: Check the MERV rating of your system – very high MERV ratings (like 14-16 or HEPA filters) may be too restrictive for a residential furnace blower without modifications. However, a decent pleated filter will significantly improve indoor air quality.
Additionally, winter is often associated with cold and flu season. A quality filter can reduce circulating viruses and germs to a degree, especially if it’s a higher MERV or combined with technology like UV or electrostatic purifiers. HEPA filters (MERV 17+) are typically used in portable air cleaners or specialized whole-house units – they remove 99.97% of tiny particles, including many viruses. While most furnaces can’t accept a true HEPA directly, you might use standalone HEPA air purifiers in bedrooms or the living room to supplement filtration during winter gatherings or if someone is sick.
Remember, dirty filters not only pollute your air, they also make your heating system work harder (meaning higher energy bills and potential breakdowns). So put a filter change on your monthly checklist in winter. It’s one of the simplest and most impactful improvements you can make to your IAQ.
Humidity: Finding the Sweet Spot
Does the air in your home feel Sahara-dry in winter? You’re not imagining it. Cold outdoor air carries very little moisture, and when it’s heated indoors, relative humidity can plummet to 20% or even lower. By contrast, a comfortable indoor relative humidity (RH) in winter is typically around 30-50%. When humidity is too low, you’ll notice static electricity zapping you, dry, itchy skin, chapped lips, and irritated sinuses. Low humidity can also make you feel colder than the actual temperature (dry air holds less heat), sometimes leading to cranking the thermostat higher.
To improve IAQ and comfort, consider using humidification in winter: –
Whole-House Humidifier: These attach to your furnace and add moisture to the warm air as it circulates. They typically have a humidistat so you can set a target RH. Whole-house units are great because they treat all the air passing through the HVAC system. If you have one, ensure it’s cleaned and the water panel (evaporator pad) is replaced annually. Then set the humidistat to around 35-40% for winter (if it’s extremely cold outside, you might need to dial it back a little to avoid condensation on windows).
Portable Humidifiers: If a whole-house unit isn’t an option, use portable room humidifiers in key areas (bedrooms, living area). Opt for cool-mist or ultrasonic models for safety. Be diligent about cleaning them according to the instructions to avoid mold or bacterial growth. Having even one good humidifier in the bedroom can significantly improve sleep in winter, resulting in a less dry throat and less congestion in the nasal passages.
Monitor levels: Get an inexpensive hygrometer to keep an eye on indoor humidity. Aim for a target of around 40%. A reading that is too high (>60%) can encourage mold growth, while a reading that is too low (<30%) can cause discomfort and static. In winter, hitting 50% might cause fog or ice on windows on frigid days, so typically shoot for a 30-45% range.
Proper humidity not only helps comfort, but it can also reduce the transmission of viruses. Research indicates that many viruses survive longer in environments with low humidity. Raising humidity into the optimal range can make the environment less hospitable to flu and cold viruses, potentially reducing their spread. It also helps your respiratory system’s natural defenses (mucus membranes) stay moist to trap germs.
Bonus: Maintaining high humidity also protects wood furniture and flooring from excessive shrinkage and cracking that can occur in arid air.
Heating System Maintenance for Cleaner Air
During furnace tune-ups (which ideally occur in the fall), technicians clean the burner and flame sensor, and inspect the venting – this ensures clean combustion and prevents the production of carbon monoxide or soot. A well-maintained furnace or boiler will burn fuel more cleanly, producing minimal carbon monoxide. However, indoor air quality is also about safety: ensure you have carbon monoxide detectors in your home, especially near sleeping areas and on each level of your home. Before heavy winter use, it’s critical to check that fuel-burning appliances are venting properly and no CO is leaking. According to the CDC, hundreds of people die in the U.S. each year from accidental CO poisoning, and thousands more are hospitalized, often in winter when heating systems run. So maintenance and detectors are literally life-savers.
Maintenance also includes cleaning out dust from ductwork (if needed) and ensuring proper ventilation:
Duct Cleaning: Not every home needs frequent duct cleaning, but if you have older ducts with a lot of dust buildup, or if you’ve had a major remodeling, cleaning ducts can remove that trapped dust and even mold. Be wary of duct cleaning scams, though; have it evaluated by a reputable pro. If you see dust blowing out of vents or smell musty odors whenever the blower runs, an inspection is warranted.
Ventilation: In winter, ventilation tends to be lowest because windows are closed. Some newer homes have ERVs/HRVs (energy recovery or heat recovery ventilators) that bring in fresh air in a controlled manner. If you have one, ensure it’s running and that the filters in it are clean. If you don’t have a mechanical fresh air system, consider briefly opening a window each day (yes, you’ll lose a bit of heat, but it brings in oxygen and flushes stale air – many IAQ experts recommend airing out for a few minutes even in winter). Cooking and cleaning activities release pollutants – use exhaust fans (such as kitchen range hoods and bathroom fans) to clear moisture and fumes, but don’t forget to allow some fresh air to make up for what’s exhausted.
Indoor pollutant sources: Keep an eye on other contributors to winter IAQ issues: for example, if you use a wood stove, have it cleaned and ensure good draft so smoke isn’t spilling inside. Avoid burning candles excessively or using strong chemical cleaners without ventilation, as these add particulates and VOCs to indoor air. Many winter-scented candles or air fresheners, while cozy, can degrade air quality – moderation and ventilation are key.
Additional IAQ Enhancements
If you want to go further: –
Air Purifiers: Consider an air purifier with a good HEPA filter for rooms where you spend a lot of time. They can remove additional fine particles and allergens that your HVAC filter might miss. Some also have activated carbon to adsorb odors and VOCs (volatile organic compounds) from sources such as paints or cooking.
– UV Lights: Some HVAC systems can be outfitted with UV-C lights near the coil. These help kill mold or bacteria on the coil and in the air that passes through it. They’re not a cure-all, but they can reduce bio aerosols. Especially useful if you’ve had mold issues in the past.
– Keeping it Clean: Simply upping your regular house cleaning routine helps – vacuum (preferably with a HEPA-filter vacuum) and dust frequently. This removes settled dust that could recirculate. To control dust mites, wash your bedding regularly in hot water. Winter means more time indoors, so a cleaner house equals cleaner air.
The Moisture Balance
Winter IAQ isn’t just about adding humidity – sometimes there’s moisture in the wrong places. Watch for condensation on windows or around doors – persistent wet spots can foster mold growth. If you notice any mold starting to grow (perhaps on a bathroom ceiling or around a window frame due to condensation), clean it promptly with an appropriate cleaner (such as a mild bleach solution or an antimicrobial cleaner) and address the underlying cause (which could be excess humidity in that room or poor insulation causing cold spots). Proper ventilation in bathrooms and kitchens helps alleviate moisture that can lead to mold growth. Run bathroom exhaust fans during and 15 minutes after showers (and check that those fans vent outside, not just into an attic). In the kitchen, use the range hood when cooking, mainly when boiling water or frying (introduces moisture and particulates).
Breathe Easy in Winter
By focusing on filter quality, maintaining a comfortable humidity level, and keeping your heating system and home clean, you can significantly improve your indoor air quality in winter. The result? You’ll likely notice fewer morning sore throats, a less dry cough, less static shock annoyance, and an overall fresher feeling at home, even when everything is closed up. Good IAQ practices also contribute to better health – potentially reducing allergy and asthma triggers and minimizing the spread of winter illnesses. Winter may mean hibernating indoors, but it doesn’t have to mean stuffy, dry air. A little attention to your home’s air systems will ensure that the air you breathe is as inviting as a warm blanket on a cold day. Stay warm, stay hydrated (inside and out!), and enjoy a healthier indoor environment all season long.
