As environmental engineering, safety & health consultants, we provide clients in MD, PA, NJ & NY with services to address their environmental concerns.

Indoor Air Quality in Winter

By on Feb 16, 2016 in Air Quality, Blog, Mold | 2 comments

How Does my Indoor Air Quality Change in the Winter?

In the winter months we are bombarded with blogs, news articles, and inserts that accompany our bills advising us to button up our home, seal all the cracks, and insulate everything to keep heating costs down. But have you asked yourself “What does this do to my indoor air quality?”

By reducing or eliminating the fresh air coming into our homes, we increase the number of allergens, irritants and pollutants indoors, creating an environment that can greatly decrease our overall health and comfort.

What Should I Be Concerned About?

There are a large variety of indoor pollutant, irritant, and allergen sources in our houses, and by sealing all the airflow pathways, these sources can quickly become a problem. Common sources include:

Combustion Equipment: Furnaces, oil/kerosene heaters, wood stoves, etc all use combustion to produce heat. Combustion is a chemical change that occurs in the presence of oxygen to produce heat, among other products. Two of the biggest concerns when combustion occurs indoors are the release of carbon monoxide and nitrogen dioxide, both of which are colorless and odorless. Carbon monoxide poisoning is a serious and potentially fatal problem, and should be taken very seriously. Nitrogen dioxide exposure could lead to respiratory problems such as chronic bronchitis.

Cleaning Products: Without the influx of fresh air during the winter months, the vapors from cleaning products can linger, leading to exposure to Volatile Organic Compounds (VOCs) and other potentially harmful gases.

Cat on bedding.

A cat relaxes on bedding.

Pets: As much as we love our fuzzy friends, they can be a source of allergens, especially in the cold months when they are inside more often. Pet dander can seriously impact the comfort of those who are allergic.

Mold: People often associate mold and mildew growth with the hot, humid summer months, but we often see mold growth in the winter as well. Occupants in a home are a large source of moisture as cooking, showering, and doing laundry can greatly increase the indoor atmosphere’s moisture content. The more moisture in the air, the higher the air dew point temperature will rise. The indoor air only has to come in contact with a cool surface (windows or poorly insulated walls, for example) and condensation will occur. From there, mold can and will grow quickly.

Potential Allergen

Dust Mite

Dust Mites: These miscroscopic creatures love to munch on our dead skin cells, which make up a large part of the dust in our homes. In the winter, we spend more time indoors, and therefore shed more of our skin cells indoors. With more food come more dust mites, and those who are sensitive to dust mite allergens will definitely take notice!

How Do I know if I Have a Problem?

Symptoms of exposure to indoor pollutants, irritants, and allergens can vary widely from one person to the next, particularly if one person is sensitized to an irritant while another is not. In most cases, paying attention to your own health and what is normal for you can tell you a great deal about your indoor environment. Are you experiencing shortness of breath, frequent headaches, rashes, or any other symptoms that seem to occur when you have been inside for a while? These symptoms may be indicative of an indoor air quality problem in your home.

Certain pollutant exposures can be detected with monitoring devices. For example, carbon monoxide detectors are readily available at home improvement stores, and can detect the presence of the deadly gas. Carbon monoxide detectors are an extremely cost effective method to alert home owners and occupants to exposure and are highly recommended, particularly if you have a natural gas furnace or hot water heater. It is best however, not to rely solely on these detectors. Perform regular maintenance on your heating equipment to ensure everything is working properly and the danger of carbon monoxide exposure is at a minimum.

mold growth

Mold grows on a surface.

Be on the look-out for mold and mildew growth that may indicate the humidity in your home is too high. During the winter, pay special attention to the windows and other cold surfaces in your home.

How Can I Improve my Indoor Air Quality?

According to the EPA, the first step to improving the indoor air quality in your home during any season is to identify and correct the source. Second, the EPA recommends improving ventilation in your home. This may be difficult in the winter months, when no one wants to open the doors or windows to let the cold air inside. However, if there are any mild weather days, it is beneficial during the winter to open the windows a bit and allow fresh air to enter your home. Finally, the EPA recommends air purifying or cleaning equipment, if necessary. Air purifiers can be purchased at home improvement or department stores. Keep in mind that air purifiers mainly only remove particulates from the air (and filters must be changed regularly). Purifiers with activated carbon filters are necessary to remove VOCs from the air as well.

In addition to the EPA’s suggestions, you can do simple things to improve your home’s indoor air quality, especially during the cold winter months.

  • Clean regularly. Remove dust (and therefore the dust mites’ dinner!) and pet dander.
  • Choose low VOC and or non-toxic products when possible.
  • Replace/clean (if filters are non-disposable) HVAC/purifier filters regularly. Most manufacturers recommend every three months or so.
  • Change bedding regularly. Dust mites can live on our sheets, and many people let their pets sleep on their bed as well. Reduce your dust mite and dander exposure by replacing your dirty sheets with clean sheets on a regular schedule.
  • Duct cleaning. Having your ducts professionally cleaned can reduce the exposure to certain irritant and allergens that may be re-circulating throughout your house via the duct system.
  • Choose another time of year for home improvement/renovation projects. Some building materials (paint, new carpet) can give off VOCs and reduce the quality of your indoor air. Choosing a time of year when you can open windows/doors during projects can significantly help reduce your exposure.

Winter can be great: warm blankets, hot chocolate, and your cozy home. But beware of hidden indoor air quality dangers that can lurk during the cold months when we tend to seal our homes up as tightly as possible. Allow your house to breath, keep it clean, and hope the Spring comes soon!


Kelly Mays

Environmental Consultant


For more information, visit these sites:

Should I Have my Air Ducts Cleaned?

EPA Recommendations on Improving Air Quality:




Designed by Interlace Communications & goMAaVA | Powered by Karl Environmental Group

Karl Environmental Group provides environmental services to residential customers, business clients, school districts (both public and private) and government agencies. Our clients represent a variety of industries and backgrounds and we pride ourselves in being able to meet their individual environmental needs with quality and efficiency. Our services include lead water testing, asbestos testing, asbestos abatement, environmental site assessment, lead paint inspection, mold sampling, and industrial hygene. We also provide certification for the OSHA Hazwoper Certification, General Industry Certification, Construction Industry Certification, EPA Lead Renovator Certification, Asbestos Worker Certification, First Aid Certification, and Basic Life Support courses. Find us on Facebook, call us at 1-800-527-5581, or find our PA location 20 Lauck Road, Mohnton, PA 19540 Tel: (610) 856-7700 or our NJ location 200 Whitehead Road, Unit #222, Hamilton, NJ 08619 Tel: (609) 365-9635