Indoor Air Quality Assessments

Our office receives calls almost daily regarding indoor air quality concerns.  During certain months of the year, i.e., winter months, we seem to receive more calls than usual, likely due to it being flu and/or allergy season.  The calls are very similar in terms of the employee concerns.  We attempt to identify specific concerns to help with our assessment.  For example, are the employees voicing concerns about an odor, do they all have scratchy eyes, or does the problem occur more in the afternoon rather than the morning.  Answers to these questions can assist in our assessment.

In many situations we evaluate common indoor air quality measurements including levels of carbon monoxide, carbon dioxide, temperature, humidity.  Measurements can be easily and quickly taken with direct reading instrumentation at numerous locations throughout the workplace.  It is also common to obtain measurements for particulate matter of various sizes.  We may also do particulate identification.  Lastly, we may take measurements for mold spores.  These are the most common measurements made when we receive a call on indoor air quality.

Although there are Cal/OSHA Permissible Exposure Limits (PELs) for carbon monoxide and carbon dioxide, the PELs are substantially higher than what would be expected to find in an office environment.  We evaluate the levels differently since these substances may be an indicator of the air quality and effectiveness of the building’s heating, ventilation and air-conditioning (HVAC) system.  The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) recommends that maximum carbon monoxide (CO) levels not exceed 9 ppm more than once per year or the ceiling limit of 35 ppm more than once per year.  A number of state public health agencies, as well as the US Environmental Protection Agency (EPA) and NIOSH (National Institute for Occupational Safety and Health) have issued recommendations on carbon dioxide levels for indoor air quality.  Carbon dioxide is naturally occurring in the air we breathe.  All of the above-named health groups concur with the 1,000 ppm limit for carbon dioxide (CO2).  ASHRAE has established Standard 62.1-2016, “Ventilation for Acceptable Indoor Air Quality,” which provides guidance on comfort for building occupants.  The ASHRAE guideline generally concurs with the 1,000 ppm recommendation, but states that “maintaining a steady-state CO2 concentration (indoors) of no greater than 700 ppm above outdoor air levels will indicate that a substantial majority of visitors entering a space will be satisfied with respect to human bioeffluents (body odor).”  Whenever we conduct an indoor air quality assessment, these are the common standards we use for our evaluation.

Air temperature and relative humidity are indicators of general office occupant comfort, but high humidity levels may also be indicative of conditions that could promote mold growth.  In their “letter of interpretation” for indoor air quality dated February 24, 2003, the U. S. Occupational Safety and Health Administration (OSHA) recommend that temperatures be controlled to between 68 and 76 degrees Fahrenheit and that relative humidity be controlled to between 20 and 60 percent for indoor office environments.  ASHRAE 62.1-2016 Section 5.9.1 states that relative humidity in occupied spaces should be limited to 65 percent or less.

Concerning particulate matter (dust on surfaces is a common complaint we hear), Cal/OSHA again has PELs, however, these levels are generally far higher than what one would commonly find in an office setting.  One approach is to evaluate the indoor environment against acceptable outdoor standards since these levels are established to minimize the impact on public health.  The California Air Resources Board (CARB) and the EPA have both set standards of exposure that we believe can be used to evaluate indoor air quality.

Feel free to call our office if you are experiencing an indoor air quality concern and we’d be happy to conduct a formal assessment for you.