Evaluating Potential Mercury Exposure in Schools

Posted on April 14th, 2020

Gym flooring - a common source for mercury exposure in schools

Gym flooring – a common source for mercury exposure in schools

Beginning in the 1960s, companies began manufacturing synthetic flooring widely used across the country in gymnasiums, multipurpose rooms, cafeterias, auditoriums, stages, nursing homes and indoor and outdoor tracks. Based on published Safety Data Sheets (SDS), several brands of this synthetic flooring material are known to contain a chemical catalyst called phenyl mercuric acetate (PMA). Over time this chemical begins to break down and emit odorless and colorless vapor into the air, primarily in areas of deterioration, high temperatures or poor ventilation.

Mercury is a neurotoxin which affects the central nervous system, brain, kidneys, lungs, skin and eyes. According to the Agency for Toxic Substances and Disease Registry (ATSDR), long-term mercury exposure can lead to headaches, tremors, insomnia, twitching, muscle atrophy, increased anxiety and changes in hearing and vision. Higher exposure to mercury can even lead to kidney issues and respiratory failure. The New Jersey Department of Health (NJDOH) has recommended a maximum concentration level of 0.8 ug/m3 of air. This level factors in body weight and exposure time and has been established to be conservatively protective of preschool-age children and older.

The New Jersey Work Environment Council is urging schools to test their flooring, test for airborne mercury and remove any confirmed mercury-containing materials. School districts should conduct a visual inspection to determine if the school contains any potentially mercury-containing polyurethane flooring and review the manufacturers SDS for PMA. It is recommended for school districts to hire an environmental consultant certified to conduct Indoor Environmental Health Assessments (IEHAs) to implement a bulk sampling plan to confirm the presence or absence of mercury. Sampling should be conducted at a frequency representative of the entire area/room and should be representative of the entire thickness of the flooring material. Samples should be analyzed by an American Industrial Hygiene Association (AIHA) accredited laboratory using the USEPA Method 7471B.

If bulk sampling results confirm any concentration of mercury, the NJDOH recommends that sampling of indoor air be conducted to evaluate the toxicity of potential mercury vapors. Since the emittance of mercury vapors is affected by temperature, these samples should be collected under normal operation conditions. If mercury vapors are detected, it is recommended that indoor air be continues to be monitored and sampled seasonally, especially in the summer seasons when temperatures are warmest, or when damage or deterioration of the flooring is observed.

If mercury concentrations are detected above 0.8 ug/m3, the school should work with their hired consultant to develop a feasible plan for reducing these mercury vapors. Such plans may include the installation of an active ventilation system, adjusting the temperature control in the room or limiting the time that individuals spend in the room. If mercury vapor concentrations cannot be feasibly reduced, the NJDOH recommends that the flooring material be removed to eliminate the potential for mercury exposure.  With school currently not in session due to the COVID-19 pandemic and school construction projects deemed essential, now is a good time for school districts to assess their gymnasium flooring for potential replacement.

JMS has assisted school districts with communication materials and indoor air testing regarding mercury in gym flooring.  Please contact JMS if you need assistance.


Courtney Palmisano

Project Scientist




Agency for Toxic Substances and Disease Registry (ATSDR). April 1999. Toxicological profile for mercury. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.

New Jersey Department of Health (DOH). February 2020. Evaluation and Management of Mercury-Containing Floors in New Jersey Schools: Guidance for School Districts and their Environmental Consultants.

New Jersey Department of Health (DOH). September 2017. Guidance for New Jersey Schools: Evaluating Mercury in Synthetic Flooring.

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