"Dear Dr. Dougherty,
In response to your request, a compliance assistance visit was conducted at your facility on October 26, 2022 to provide you with assistance regarding air quality concerns. The concerns that you were specifically interested in assistance with pertained to odor complaints stemming from a previous sewer leak in the crawlspace beneath the elementary school. A walk through of this area of concern was conducted. The sewage leak was previously cleaned up by a professional vendor and the space was currently under constant dehumidification. Some standard screening measurements were taken during this visit to evaluate general indoor air quality as well as determine if an immediate atmospheric hazard existed. First, oxygen, hydrogen sulfide, explosive atmosphere, and carbon monoxide was measured. These are appropriate to screen for when trying to assess an atmosphere for immediate safety since hydrogen sulfide (toxic in sufficient levels) and methane (explosive in sufficient quantities) are major constituents of raw human sewage. Hydrogen sulfide, carbon monoxide, and lower explosive limit (measures explosivity of atmosphere) all read 0 throughout the areas visited. Oxygen levels read 20.9 % throughout the walk around, which is the natural atmospheric level of this gas in our atmosphere. Carbon dioxide (CO2) is a normal constituent of exhaled breath and, if monitored, can be used as a screening technique to evaluate whether adequate amounts of fresh air are being introduced into a given area to dilute residual nuisance odors. The American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE Standard 62.1 - 2004, Ventilation for Acceptable Indoor Air Quality – Atlanta, GA) and the National Institute for Occupational Safety and Health (NIOSH) have both established an upper guideline of 1000 parts per million (ppm) of CO2 in indoor air. When CO2 concentrations are more than 1000 ppm (3 to 4 times the outside level), building occupant complaints tend to increase. Carbon dioxide values in exceedance of this comfort guideline can be decreased, along with the associated complaints, by increasing the amount of fresh air introduced into the ventilation system. The highest CO2 value measured during the walk around was 892 ppm which is well below the comfort guideline of 1000 ppm as well as the permissible exposure limit of 10,000 ppm. No strange odors were detected by the hygienist. No visible mold was detected. A possible air contaminant source could not be found."
Peter J. Moles,
New York State Department of Labor Public Employee Safety & Health Bureau Consultation Program
Associate Industrial Hygienist