The objectives of this survey are to evaluate the chemical exposure of the artistes participated in the fire dance act and the exposure of the technicians during the show time. Air samples collected were analyzed for carbon black, total hydrocarbon and sulfur dioxide. The concentrations of volatile organic carbon were monitored at real time.
Totally forty one samples have been collected for personal exposure monitoring, general area monitoring, backgrounds and quality control. All the personal samples indicate that the airborne concentrations of the target contaminants are all below their respective occupational exposure limits. The background levels are below detection limits. The area samples showed that carbon black and hydrocarbon were detected at the grid area during show time, however, the levels are far below the occupational exposure limits.

…a demonstration session which simulated the actual conditions of the show was conducted for sampling purpose. Personal exposure monitoring of the artistes participated in the fire dance act and technicians worked at the basement were conducted during the demonstration.

Isopar G and Isopar M are used as fuel in the fire dance act. They are isoparaffinic hydrocarbons. The initial boiling points of Isopar G and Isopar M are 163 oC and 223 oC respectively, thus, they are not volatile. High concentrations of Isopars are irritating to the eyes and the respiratory tract, and may cause headaches and dizziness. Both manufacturers (Univar and Exxon Mobil) recommended an occupational exposure limit of 1200 mg/m3 TWA (Isopar G 196 ppm, Isopar M 152 ppm) based on total hydrocarbon.
Isopar Vapors Airborne Isopars were sampled by “3M” Passive Organic Vapor Monitors (POVM) and the analysis also followed the standard method of 3M Company. The results were expressed as total hydrocarbons (as hexane). The ambient concentrations of organic vapors around the stage during the demonstration session of the fire dance act were monitored in real-time by an electronic volatile organic vapor (VOC) monitor.

Complete combustion of Isopars will form carbon dioxide and water vapor, which are harmless, while incomplete combustion will generate carbon black and carbon monoxide. Carbon monoxide produced in the show condition should be low, so carbon black was the target of monitoring.....
Isopar Vapors All the field survey and analyzed samples were below TLV-TWA except a short period of real-time monitoring (about 1 minute) during the extinction of the fire gear at the basement after the fire dance act during the show time.
Personal exposure The exposure levels of one artist is 52 ppm total hydrocarbon (as hexane) while the other one is lower than the detection limit.
Area contamination All the results of POVM are lower than the detection limit except one (at right side of the grid when facing audience) with a concentration of 5.1 ppm.
During fire gear extinction A peak level of 518 ppm (as isobutylene) was registered. Levels of 400 – 500 ppm lasted for about 1 minute; for most of the time, the readings were within the range of 30 – 90 ppm.VOC around a stationary fire pole
The measured VOC concentrations closed to an unlighted but fueled fire pole (background, before ignition and during burning) were very low, within 2 ppm (as isobutylene). The readings boosted to 40 – 70 ppm after fire extinction for a short period.
These 2 tests showed that Isopars are non-volatile at ambient temperature but are highly vaporized at high temperature.
Conversion between hydrocarbons readings The molecular weights of Isopar G, Isopar M, isobutylene and hexane are 145, 191, 56 and 86 respectively. The TLV-TWA ppm concentrations of Isopars as isobutylene and hexane will have figures higher by 1 – 3 folds. However, the total hydrocarbons readings are compared on equal basis in the exposure evaluation, this approach provided a higher safety margin.
Carbon Black Personal exposure All the masses of carbon black collected at the filters were less than the detection limit of the method except one (but still within the TLV-TWA). This indicates the carbon black concentrations in air were low.

Discussion and Conclusion The duration of the fire dance act was about 5 minutes in the show while the demonstration session lasted for more than 10 minutes. The exposure times of the artistes to the contaminants were extended in the demonstration. All the personal exposure readings are less than the occupational exposure limits. Furthermore, occupational exposure limit is time-weighted average based on 8- hour shift per day and the exposure of the artistes and technicians to the contaminants are intermittent and limited to short periods only, hence the occupational exposure should be well below the referred standards.