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Indoor air quality (IAQ) is an increasingly important topic as more people spend most of their time inside. Poor IAQ can cause a variety of health issues, including allergies, asthma, and other respiratory problems.1  
This blog post covers some of the most frequently asked questions about IAQ and what can be done to improve the air quality for homes, offices, etc.  


What causes poor indoor air quality? 
The most common sources of indoor air pollution include CO2, mold, pet dander, cleaning chemicals, pesticides, radon, and tobacco smoke. Contemporary buildings are sealed to preserve heat and air conditioning. However, poorly ventilated buildings can trap pollutants inside, making internal air more polluted than outside. 


How can I tell if my indoor air quality is poor?  
There are a few signs that can indicate poor IAQ, such as frequent headaches, dizziness, fatigue, and respiratory problems.2 If you notice any of these symptoms, it may be a sign that the air needs to be improved. Any visible mold growth or musty odors can also be a sign of poor IAQ. 
Another way to check is by using an air monitor like the Aranet4 Home. These devices are wireless, portable, and give regular updates regarding health-centric metrics like CO2.  


What can I do to improve indoor air quality? 
We recently published a blog detailing several tips to keep IAQ optimal. However, here’s a quick breakdown of ways to improve things: 

  • Regularly open windows and doors. This will allow CO2 to disperse and allow fresh air to circulate. 
  • Regularly clean and vacuum homes and offices to remove dust and other particles. 
  • Use natural cleaning products or make your own cleaning solutions to avoid harsh chemicals. 
  • Buy some houseplants for homes and offices. These actively absorb CO2 and release clean oxygen.  
  • Install air filters in heating and cooling systems to remove pollutants. 
  • Avoid smoking inside and/or use air purifiers to remove smoke particles. 
  • Test areas for radon and take steps to fix the problem if elevated levels are found. 
  • Keep moisture levels low. This helps prevent mold growth. 
  • Regularly maintain your heating, ventilation, and air conditioning systems. Older systems can often become dirty, requiring cleaning, filter changes, or other maintenance. 


Are air purifiers effective for improving indoor air quality? 
Air purifiers can be effective in removing pollutants from the air, but they are not a substitute for good ventilation and regular cleaning.3 It does help to choose an air purifier with a high-efficiency particulate arrestance (HEPA) filter. These filters are specially designed to remove particles as small as 0.3 microns. Lastly, it is important to regularly change air purifier filters to ensure they continue functioning effectively.


Is it safe to use essential oils to improve indoor air quality? 
While some sources disagree, the latest research points to essential oils increasing indoor pollution.4 Furthermore, some essential oils, such as tea tree and eucalyptus, can be dangerous if ingested or applied directly to the skin in large concentrations.  
While they do smell fantastic, essential oils cover smells, rather than reducing pollution.  


Is it necessary to have my indoor air quality tested? 
It is not always necessary to have your indoor air quality tested, but it can be helpful if you suspect there may be a problem. 
An easy way to test air quality is by using an air monitor to track the concentration of contaminants like CO2. As the presence of CO2 correlates with the concentration of airborne pathogens like influenza and the common cold5, air monitors are simple, real-world indicators of indoor air quality.  

What is a normal CO2 concentration? 
A normal CO2 concentration is about 400 ppm outdoors. Inside a well-ventilated building, normal CO2 levels range from 400-1000 ppm.  
When the saturation of CO2 is greater than 1000 ppm, people start to experience drowsiness. Levels above 2000 ppm are associated with sleepiness, headaches, and other unpleasant side effects.6  


Does the humidity level affect indoor air quality?  

Yes. Humidity levels affect indoor air quality. The recommended humidity level is between 30-50%. Too high a humidity, and mold and bacteria are more likely to grow. On the other hand, low humidity is associated with dryness and respiratory illnesses. 7 


Do houseplants help improve indoor air quality? 
Maybe. One famous study conducted by NASA identified plants as removing pollutants. However, this was in small environments simulating a space-like scenario.
However, plants are proven to increase humidity, release oxygen, and absorb CO2. The Spider Plant, Snake Plant, Boston Fern, Golden Pothos, and Dracaena are closely associated with air-cleaning abilities.  




  1. Indoor Air Quality.
  2. 10 Signs of Poor Indoor Air Quality. 
  3. Do Air Purifiers Work? 
  4. Are Essential Oils Hurting Your Indoor Air Quality? 
  5. Exhaled CO2 as a COVID-19 Infection Risk Proxy for Different Indoor Environments and Activities. 
  6. Carbon Dioxide.
  7. Indirect health effects of relative humidity in indoor environments. 
  8. A study of interior landscape plants for indoor air pollution abatement. 

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