Hazardous Materials Response teams and individuals performing Health Hazard investigations (Health Inspectors, Fire and Safety Inspectors) are many times called to School and Public Building occupancies. Typical responses are for hydrocarbon releases, hydrocarbon based chemical spills,
or "Unknown Source" odors, with individuals complaining of symptomatic exposures.

Tests are run on site, and many times follow up environmental testing is performed. Initial tests are compared to levels identified as Immediately Dangerous to Life or Health (less than 19.5% O2, greater than 20% of the lower explosive limit of a combustible vapor), and other on site testing, such as those tests performed with organic vapor analyzers or length of stain testing equipment, are performed.

Initial tests show NO Immediately Dangerous to Life or Health (IDLH) atmospheres, yet symptoms or odors persist.  The question raised by school officials or operators of public buildings in situations such as this is: IS THIS BUILDING SAFE TO OCCUPY?

Typically, test data collected on site by HAZMAT or Health Hazard personnel is compared to a variety of standards.  These include the Permissible Exposure Limits (PEL) developed by the US Department of Labor, Occupational Safety and Health Administration; the Recommended Exposure
Limits published by the US Public Health Service, Centers for Disease Control and Prevention: National Institute for Occupational Safety and Health (NIOSH) ; or those of other groups with recommendations in this area, such as the American Industrial Hygiene Association (AIHA) or the American Conference of Governmental Industrial Hygienists (ACGIH). 

These recommendations, however, are designed to protect the occupational population, typically adults over the age of 18.  It is these individuals who are allowed by law to work in dangerous environments. The levels cited do not and are not designed to protect at risk populations such as children in schools or the elderly.

Personnel investigating these occurrences may next turn to the US Public Health Service: Agency for Toxic Substances and Disease Registry (ATSDR) published Minimal Risk Levels (MRL). These levels are designed to serve as a screening tool to help investigators decide where adverse health
effects are not likely to occur, and they take into account the most sensitive populations (children, the elderly and those with compromise immune systems). MRL are published for acute exposures (less than 2 weeks), for intermediate exposure ( 2 weeks to 1 year) and for chronic exposures
(greater than 1 year).

Many times the chronic exposure levels are used as re-occupancy criteria by health departments after the release of hazardous substances, and these are sometimes referred to as the "walk-away" levels.

HAZMAT personnel at a site which exhibits characteristics above the ATSDR acute risk level may wish to recommend evacuation for all but brief (which may be construed as up to two week) exposures.

The dilemma, however, is this:  the ATSDR criteria, and similar criteria published by the US Environmental Protection Agency (EPA), are re-occupancy or ACCEPTABLE levels, those at which there is no appreciable risk of an adverse effect occurring. The question remains, at what levels
should recommendations be made to evacuate these target occupancies, IMMEDIATELY!

To address this issue, the Pennsylvania Department of Health has researched and issued guidelines for the evacuation of schools (and by interpretation, public occupancies with school age children in them). 

These can be found on the PA Department of Health Website at www.state.pa.health/site, or by searching the PA Department of Health web site for the "Tools for Schools " criteria. The PA DOH has RECOMMENDED THE EVACUATION OF SCHOOLS WHERE 10 PPM OR MORE OF TOTAL HYDROCARBONS ARE PRESENT, OR .1 PPM OR MORE OF BENZENE IS PRESENT.  These levels are above the ATSDR minimal risk levels, but well below the occupational exposure criteria.

Additional information relative to toxins in these specialized environments can be found on the web page as well, such as the re-occupancy criteria for schools after the release of mercury.

Hazardous Materials personnel in Pennsylvania, as well as in other jurisdictions who choose to adopt or reference the PA DOH evacuation criteria, should be prepared to test on site for total hydrocarbons and benzene to the referenced levels, and subsequently recommend evacuation of
structures due to health hazards when these levels are identified.

NEXT: Testing for the 10 PPM total hydrocarbon level or the .1 ppm benzene level on site, OR, equipment and tests that are useful when investigating releases or potential releases of hydrocarbons and unknown odors in SCHOOLS and Public Occupancies.

More information on this subject can be acquired from Dr. Joseph Cocciardi