Intervention to reduce gymnast exposure to flame retardants from pit foam: A case study.

Gymnasts can have high exposures to flame retardants (FRs), which are used in gymnastics safety equipment such as the loose foam pit. Therefore, we aimed to reduce gymnast exposure to FRs by replacing the foam in the pit using foam free of additive FR and measuring personal exposure during practice using hand-wipes. To assure maintenance of fire safety we first conducted a flammability study and facilitated a fire inspection for our partner gym. The FR-treated cubes had similar heat release rates to the non-FR treated cubes, required a 11 cm larger flame size applied for 6 s longer to ignite, and took 4 min longer to reach peak flame height. Based on these findings and the presence of other fire safety measures including smoke detectors and a sprinkler system, the local fire and building departments approved replacement of the foam pit with FR-free foam. We then replaced foam in the gym's pit, verified it was free of any additive FRs, and quantified common halogenated and organophosphate FRs on hand-wipes collected from ten collegiate gymnasts before and after practice, pre- and post-intervention. We observed a 5-fold decline in the median mass of FRs found in pit foam that accumulated on hand-wipes during practice among gymnasts who used the foam pit (p = 0.02), indicating that replacing the foam in a pit using materials free of FRs can reduce gymnast exposure to these chemicals during practice.

A means to estimate thermal and kinetic parameters of coal dust layer from hot surface ignition tests.

A method to estimate thermal and kinetic parameters of Pittsburgh seam coal subject to thermal runaway is presented using the standard ASTM E 2021 hot surface ignition test apparatus. Parameters include thermal conductivity (k), activation energy (E), coupled term (QA) of heat of reaction (Q) and pre-exponential factor (A) which are required, but rarely known input values to determine the thermal runaway propensity of a dust material. Four different dust layer thicknesses: 6.4, 12.7, 19.1 and 25.4mm, are tested, and among them, a single steady state dust layer temperature profile of 12.7 mm thick dust layer is used to estimate k, E and QA. k is calculated by equating heat flux from the hot surface layer and heat loss rate on the boundary assuming negligible heat generation in the coal dust layer at a low hot surface temperature. E and QA are calculated by optimizing a numerically estimated steady state dust layer temperature distribution to the experimentally obtained temperature profile of a 12.7 mm thick dust layer. Two unknowns, E and QA, are reduced to one from the correlation of E and QA obtained at criticality of thermal runaway. The estimated k is 0.1 W/mK matching the previously reported value. E ranges from 61.7 to 83.1 kJ/mol, and the corresponding QA ranges from 1.7 x 10(9) to 4.8 x 10(11)J/kg s. The mean values of E (72.4 kJ/mol) and QA (2.8 x 10(10)J/kg s) are used to predict the critical hot surface temperatures for other thicknesses, and good agreement is observed between measured and experimental values. Also, the estimated E and QA ranges match the corresponding ranges calculated from the multiple tests method and values reported in previous research.