A Volatile Organic Compound (VOC) is defined as any compound containing carbon that can be readily vaporized, except methane. VOCs, are measured as the totality of its mixed gases indoor environments from cleaning and disinfecting products, paints, wood preservatives, carpeting, building materials, aerosols, insect repellents, microbial growth, and a host of other sources.

At elevated levels, VOCs can cause eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidneys, and central nervous system. Some organics (such as benzene) are suspected or known to cause cancer. Key signs or symptoms associated with exposure to elevated levels of VOCs include eye infections and irritation, nose and throat discomfort, headaches, allergic skin reactions, shortness of breath, signs of poisoning, nausea, vomiting, nose bleeding, fatigue, and dizziness.

According to Indoor Air Quality standards such as the WELL Building Standard and the US Green Building Council (USGBC), VOC levels are considered elevated above 300-500 microgram/m3. Depending on the mix of the VOCs and their individual molecular weights, that can be translated to about 200 - 450 ppb (parts per billion); OSHA does not generally regulate the total combination of VOC compounds, instead it regulates limits for some specific VOC compounds

Carbon dioxide (eCO2) equivalents, or for short eCO2, are derived from the measurements of the mixed gases, tVOCs, and describe the quality of indoor air in equivalent units of eCO2. Traditionally, indoor air quality indices have been limited to the measurement of temperature, humidity, and carbon dioxide alone. eCO2, however, tracks changes in eCO2 levels but also contains information about additional harmful mixed gases and odorous events. In contrast, a eCO2 sensor detects just the exhaled eCO2 from the room’s occupants.

396 ppm (parts per million) was the mean average annualized global outdoor eCO2 level reported at the end of August 2013 by NOAA. OSHA states that 1,000 ppm should be used as an upper limit for indoor levels, as a guideline for occupant comfort; a level higher than 1,000 ppm indicates inadequate ventilation. EPA testing recommends Carbon Dioxide levels to not exceed 800 ppm. American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) and the American Society of Testing and Materials (ASTM) suggest indoor levels should not exceed 700 ppm and 650 ppm above outdoor air, respectively. At levels above 2,000 ppm for an extended period of time complaints such as headaches, fatigue, and eye and throat irritation are typical and more widespread.

Relative humidity (rH) is among the most common of indoor air environmental factors implicated in occupant discomfort. Elevated humidity has been shown to be associated with a worsened perception of Indoor Air Quality. High %rH is also an indicator of conditions favorable to mold and microbial growth.

ASHRAE (American Society of Heating Refrigeration and Air-Conditioning Engineers) recommends a maximum of approximately 56%rH at 80°F and up to approximately 86%rH at 67°F (at standard atmospheric pressure). Clothing, radiant heat and many other factors influence the recommendations of this standard. This is based on their standard Graphical Comfort Zone Method. Per ASHRAE there are not any established lower humidity limits for thermal comfort. However, non-thermal comfort factors such as skin drying, irritation of mucus membranes, dryness of the eyes, and static electricity generation, may place limits on the acceptability of very low humidity environments.

The latest version of the lüft app includes a Mold Risk Indicator. The app analyzes the CURRENT condition of temperature and humidity and determines how likely it is that mold will develop. The Mold Risk is provided on a 5-level scale from very low to very high risk. Very low risk means it would take more than a year at this condition to develop mold, if any. Very high risk means it would only take three or fewer days for surface mold to develop. Please not that the device does not measure mold but indicates risk of mold developing. Additionally, other surfaces within the house, such as windows and outside walls, may begin to see mold developing at lower risk levels.  This is a function of the differential temperature and humidity conditions prevailing on any given wall or window surface as compared to readings taken in open air.

When your lüft monitor reports Radon levels above 2pCi/l for extended periods of time, please, contact a Radon Inspection and Mitigation professional. When VOC or eCO2 levels are persistently high, contact a certified Indoor Air Quality professional to seek advice or to perform additional testing. Improving home ventilation will temporarily mitigate the health concerns but it does not address a potential underlying that is giving rise to elevated readings.