Indoor Air Quality in Winter

The weather outside may be frightful, but the air inside could easily be worse. Although the holiday season is here, it’s important to think about the effects that winter will have on your indoor air quality.

Why does indoor air quality get worse in winter? Unfortunately, the cold season is one of the worst times of the year for indoor air quality, either at home or at work. People stay inside tightly-sealed buildings while reducing the amount of warm air escaping outdoors, replacing ventilation for heating. This means people are breathing a greater amount of recirculated — not fresh — air. This traps pollutants and moisture in, including dust, pollen, spores, and more, which increase the concentration of contaminants in the air.

But now, with Covid-19, and people being cooped up indoors up to 90% of the time and with Christmas and New Year holidays around the corner, it also increases the risk of spreading the virus in enclosed environments.

What Makes Indoor Air Quality Dangerous?

1. Sealing in the pollution

When it’s cold, everyone shuts up all their windows and doors. However, this traps in VOCs, dust, and other harmful airborne molecules, which significantly decreases air circulation. According to the EPA, this is a cause of indoor air pollution, exacerbated by the winter when people sealed off their windows and doors.

2. Wood and Other Heat Sources

For homes with a fireplace, wood is often preferred to avoid high electricity and gas bill. However, wood smoke, if left unchecked, can raise PM2.5 to hazardous levels. Other sources such as a heater can make the air warmer but very dry, which can cause cracked skin and lips. Beyond the skin, excessively dry air can cause a dry nose and throat, which lowers our immunity and increases the chance of getting sick.

3. Over-humidifying

Cold air is usually dry, so people tend to compensate this by turning on their humidifiers. A humidifier will add moisture to the air and reduce dryness of your skin, lips, nose and throat. Just be sure to use a humidistat to prevent the humidity from getting too high, which could lead to mould growth and dust mites, which can cause serious problems for both buildings and people’s health.

4. Being Indoors For Too Long

The air we exhale emits a lot of water vapor every minute. Tiny water droplets floating in the air, including our body odor, are trapped inside, which creates a smell. This slowly increases air temperature, which also increases the humidity. With higher humidity and zero air circulation, the environment is quicker to be less hygienic and prone to bacteria and viruses.

So, What Can We Do?

  1. Open the windows occasionally to ventilate with fresh air, but beware of outdoor air pollution.
  2. Use an air purifier and check the air filter from time to time, replacing them as needed.
  3. Safely store toxic chemicals (paint, spray, etc…) in a cabinet instead of leaving them out in the open.
  4. Avoid smoking indoors.
  5. Clean your home occasionally (vacuum the floor, wash the bed sheets, etc…) to avoid indoor pollutants from piling up.
  6. Use an indoor air quality monitor and act when needed when readings are not in the safe zone. Like PiCO Home!

Using PiCO Home

With PiCO Home in our office, we are able to monitor the air quality levels throughout the day. It seems that the air quality is good when we’re home, but is high when we work, due to the heater and humidifier. Knowing this, we adjust them as needed and turn on our air purifier to keep our environment safe and healthy!

Our quality levels in our office from Monday through Wednesday.

PiCO Home is our flagship smart home device that measures the air quality around you to keep you and your family safe. In addition to humidity, VOCs, carbon dioxide, and the temperature, it also measures PM 2.5 and PM 10.

The device comes with a smart mobile app that informs you when pollution levels are bad, thus playing a crucial role to help you protect yourself from unhealthy air during this chilly, winter season!

PiCO Home is available now on Amazon.

To inquire more about Brilliant & Company, please do not hesitate to drop us a line:



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Brilliant & Company

Brilliant & Company


We are based in Seoul, South Korea. Our mission is to create a healthier living environment.