Every office has some employees with headaches.  What number of headaches would you deem excessive? What’s normal?

Indoor air contaminants are present in every home, school and office.  But are the concentrations high enough to warrant concern?  What’s safe?

When measuring indoor air quality parameters such as carbon monoxide, VOCs, mold or allergens, you’ll be faced with interpreting the results.  Your clients want straightforward answers to two common questions, “Is this normal?” and “Is this safe?”  At first glance, these questions seem identical, but there is an important distinction I would like to highlight in this post.

“Is this normal?” looks at the concentrations found in similar building types in a similar climate zone during a similar time of year. Concentrations of contaminants are usually in flux, leaving a normal, lognormal or other distribution.  Plotting out historical data from similar buildings will typically create a bell shaped curve that can help answer the question, “Is this normal”?  When taking measurements, you may record a reading that falls a few standard deviations from the mean.  This is a good indication that the level is not normal. (more…)