WHY DO WE CARE?
We spend 90% of our time indoors. Indoor air quality is a problem throughout the worl and indoor pollution levels are up to 8 times higher than outdoors. Indoor air pollution is linked to various deadly diseases like ischaemic heart disease and lower respiratory infection. The darker and cooler colored zones represent areas with higher indoor air pollution, while the lighter, warmer colored zones represent areas with lower indoor air pollution. (A specific threshold has not been determined internationally for what is a dangerous level, but PM levels in the Cognitive Effects study mentioned in the last post found levels ranging from 1.26 to 3.35 ug/m3.)
VOCs are one component of indoor air quality that we can mitigate through our selection of healthy materials. As mentioned in the last post, "conventional" VOC levels --meaning those that occur in a building that does not selectively choose materials with occupant health in mind-- have been linked to reduced cognitive function.
WHAT IS A VOC?
A VOC or volatile organic compound is any compound of carbon (excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates and ammonium carbonate), which participates in atmospheric photochemical reactions. The graph below shows which VOCs were the worst offenders in the recent study: "Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments."
31 of the most common VOCs are:
- 1,2, 4 Trimethylbenzene
- acetone benzene
- freon 113
- heptane hexane
- methylene chloride
- toluene trans-1,2-Dichloroethene
- "aldehyde" compounds like formaldehyde sometimes count as separate from VOCs (especially by large companies that will measure VOCs for one price and aldehyde components at an additional cost.)
HOW DO WE MEASURE VOC LEVELS?
VOC levels can be measured either by collecting an air sample or by continuous monitoring. Each has its own cost and benefit.
A Summa Canister or Passive Badge Air Sample can be used to measure the VOC content of captured air from a space. This is the most scientifically accurate methodology as it captures the full profile of VOC offenders and gives an accurate measure of each individual VOC type. Multiple measurements are typically taken to ensure accuracy since different locations in the same space and measurements taken at different times may have different results.
Continuous monitoring is possible with mountable and hand held devices, however unlike the air sample collection method, it does not provide full analysis of theVOCs. It only provides the ppm measurement of the total VOC content. The mountable one from E-instruments can gather up to 2,000 points and be read remotely using a bluetooth sensor.
Foobot and its competitors Koto Air and Withings provide at-home VOC monitoring in a sleek, user friendly format. Withings offers continuos, remotely accessible VOC monitoring, blinking red and sending a notification when unhealthy levels are reached.
Aircuity is a device that has been installed in schools, offices, laboratories and healthcare facilities. It continuously monitors VOCs and CO2 levels and kicks up the ventilation in a space whenever certain levels are exceeded. For example, envision a school cafeteria - for most hours of the day, there are no students there. The Aircuity system would kick up the ventilation rates when it senses more students present (through increased CO2 levels) to keep the air clean. It has been helpful in creating NetZero spaces by reducing overall building energy use. This is the system installed in the Net Zero Lab building that Z reviewed in a Monday morning meeting a several weeks back.