Heat stress risk among New York City public school kitchen workers: a quantitative exposure assessment
Abstract No:
1668
Abstract Type:
Student Poster
Authors:
A Ierardi1, B Pavilonis1
Institutions:
1CUNY School of Public Health, New York, NY
Presenter:
A. Michael Ierardi, MES
CUNY School of Public Health
CUNY School of Public Health
Faculty Advisor:
Dr. Brian Pavilonis, PhD, CIH
CUNY School of Public Health
CUNY School of Public Health
Description:
The objective of the current study was to quantify the extent of heat stress in New York City public school kitchens and to assess potential risk of developing a heat-related illness and/or acute injury. Full-shift indoor Wet Bulb Globe Temperature (WBGT) indices, as well as indoor CO2 and CO concentrations, were measured at 10 school kitchens. A quantitative exposure assessment for three metabolic work-rate scenarios (light, moderate, heavy) was performed in accordance with the Heat Hazard Assessment as described in the Occupational Safety and Health Administration's (OSHA) Technical Manual.
Situation/Problem:
Excessive heat exposure is a significant occupational health and safety concern in both outdoor and indoor environments. Between 2000 and 2010, there were 359 occupational heat-related deaths in the U.S., resulting in a yearly average rate of 2.2 deaths per 100,000 workers. The risk of heat-related illness among those employed in the construction industry, military, and, to a lesser extent, foundries has been previously characterized. In addition to heat-related illnesses, excessive heat exposure has also been associated with declines in cognitive function (i.e., decision-making abilities) and increased risk-taking behavior, ultimately resulting in an increased risk of accidents and injuries. One example of a work environment that is often overlooked when discussing occupational heat exposure, but that nevertheless potentially poses an increased risk of a heat-related illness/injury, is the commercial kitchen. Indeed, there is a paucity of information in the available peer-reviewed literature describing environmental heat parameters in commercial kitchens, and not a single study has performed a quantitative exposure assessment to assess potential risk of health-related illness among workers in this occupational setting. The primary purpose of the current study was to quantify the extent of heat stress in New York City school kitchens and the subsequent risk of heat-related illness and/or acute injury among workers who are employed in these environments.
Methods:
Selection of Schools: Ten (10) public schools were selected for evaluation in conjunction with the Health and Safety Department of DC-37, New York City's largest labor union. It was determined prior to the initiation of the study that Institutional Review Board (IRB) approval was not required by the City University of New York (CUNY).
Study Design: Between 2019 May 31 and September 26, full-shift (~6 to 7 hours) indoor WBGT index (WBGTin) measurements in °C were collected at the 10 school kitchens. A quantitative exposure assessment was performed according to OSHA's Heat Hazard Assessment along with a walk-through. Metabolic work-rate scenarios (in Watts [W]) of 180 (light work), 300 (moderate work), and 415 (heavy work) were evaluated. The application of a clothing adjustment factor was not necessary (i.e., WBGT effective [WBGTeff] was equal to WBGTin) because standard cotton/light polyester short-sleeve shirts and pants were worn by staff. WBGTeff and the metabolic work-rates were compared to the American Conference of Governmental Industrial Hygienist's (ACGIH) Action Limits and Threshold Limit Values (TLV) for heat stress. A publicly-available computer-based tool created by the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) was utilized to calculate the Action Limits and TLVs for each work-rate scenario; this tool was previously featured in the August 2019 edition of AIHA's magazine, The Synergist. Recommendations regarding work/rest schedules based on IRSST's calculator were provided for sites in which the WBGTeff exceeded or was within 1°C of either the Action Limit or TLV for the full-shift.
Environmental Sampling: A heat stress monitor (QUESTemp Heat Stress Monitor Kit QT36, 3M, Saint Paul, MN, USA) was utilized to measure and record WBGTin in the 10 school kitchens every minute over the full-shift sampling period. The monitor was then placed as close to the ovens as possible, which represented the "worst-case" heat exposure zone for a kitchen worker. In addition, a data-logging indoor air quality meter (7545 IAQ-Calc, TSI, Shoreview, MN, USA) was co-located with the heat stress monitor, and was used simultaneously to measure carbon dioxide (CO2) and carbon monoxide (CO) levels inside the school kitchens every 10 seconds over the full-shift.
Kitchen Visual Surveys: Additional data was collected to further characterize the work environments, including location of each kitchen within the school, the type of cooking equipment present and operational during the shift, total approximate volume of the kitchen, the number of doors open to non-kitchen areas, the number of open windows, the number of kitchen staff present, and the total number of meals (breakfast and lunch) served over the course of the shift. Average outdoor temperature and humidity between 7:00 AM and 3:00 PM were also recorded for each sampling day.
Study Design: Between 2019 May 31 and September 26, full-shift (~6 to 7 hours) indoor WBGT index (WBGTin) measurements in °C were collected at the 10 school kitchens. A quantitative exposure assessment was performed according to OSHA's Heat Hazard Assessment along with a walk-through. Metabolic work-rate scenarios (in Watts [W]) of 180 (light work), 300 (moderate work), and 415 (heavy work) were evaluated. The application of a clothing adjustment factor was not necessary (i.e., WBGT effective [WBGTeff] was equal to WBGTin) because standard cotton/light polyester short-sleeve shirts and pants were worn by staff. WBGTeff and the metabolic work-rates were compared to the American Conference of Governmental Industrial Hygienist's (ACGIH) Action Limits and Threshold Limit Values (TLV) for heat stress. A publicly-available computer-based tool created by the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) was utilized to calculate the Action Limits and TLVs for each work-rate scenario; this tool was previously featured in the August 2019 edition of AIHA's magazine, The Synergist. Recommendations regarding work/rest schedules based on IRSST's calculator were provided for sites in which the WBGTeff exceeded or was within 1°C of either the Action Limit or TLV for the full-shift.
Environmental Sampling: A heat stress monitor (QUESTemp Heat Stress Monitor Kit QT36, 3M, Saint Paul, MN, USA) was utilized to measure and record WBGTin in the 10 school kitchens every minute over the full-shift sampling period. The monitor was then placed as close to the ovens as possible, which represented the "worst-case" heat exposure zone for a kitchen worker. In addition, a data-logging indoor air quality meter (7545 IAQ-Calc, TSI, Shoreview, MN, USA) was co-located with the heat stress monitor, and was used simultaneously to measure carbon dioxide (CO2) and carbon monoxide (CO) levels inside the school kitchens every 10 seconds over the full-shift.
Kitchen Visual Surveys: Additional data was collected to further characterize the work environments, including location of each kitchen within the school, the type of cooking equipment present and operational during the shift, total approximate volume of the kitchen, the number of doors open to non-kitchen areas, the number of open windows, the number of kitchen staff present, and the total number of meals (breakfast and lunch) served over the course of the shift. Average outdoor temperature and humidity between 7:00 AM and 3:00 PM were also recorded for each sampling day.
Results / Conclusions:
Results: Average outdoor temperatures during the shifts ranged from 19.4˚C (67.0˚F) on June 14 to 28.3˚C (83.0˚F) on July 12; average humidity during the shift ranged from 46% on August 29 to 76% on June 2. There were electric ovens, steamers, standing warmers, and table warmers present and operational in all of the school kitchens. Gas stove tops were found in only half of the schools evaluated; none of the gas stove tops were used for daily meal service and they were therefore generally not operational during the sampling events. One school also had an electric hot plate that was operational during meal service. The kitchens ranged in size from approximately 6,800 to 45,600 ft3, and the number of total meals served ranged from 7 to 1,257.
The overall average WBGTin for all 10 sites was approximately 25.0˚C (77.0˚F; standard deviation [SD] = 2.0˚C). Action Limits of 28.1°C (82.6°F), 25.0°C (77.0°F), and 23.0°C (73.4°F), expressed as WBGTeff, were calculated for the light, moderate, and heavy work-rate scenarios, respectively. Similarly, TLVs of 30.8°C (87.4°F), 28.2°C (82.8°F), and 26.6°C (79.9°F) were calculated for the light, moderate, and heavy work-rate scenarios, respectively. Regarding the estimated Action Limit, 10% of school kitchens sampled exceeded this recommended limit for the light work-rate scenario, 60% of schools exceeded this limit for the moderate work-rate scenario, and 80% of schools exceeded this limit for the heavy work-rate scenario. For the TLV, none of the kitchens exceeded this limit for the light or moderate work-rate scenarios, while 30% of kitchens were in excess of this limit for the heavy work-rate scenario. Average full-shift CO2 and CO air concentrations ranged from 435 to 911 ppm (mean = 648; SD = 158) and 0.0 to 3.2 ppm (mean = 0.9; SD = 0.9), respectively. These levels were well below AGCIH TLVs for these chemicals, and indicated that sufficient outdoor air exchange was achieved at each sampling site.
Conclusions: Overall, the heat stress and indoor air quality data presented herein suggest that kitchen staff employed in New York City public schools may be exposed to excessive indoor heat levels, depending on their individual work-rate output and degree of heat acclimatization. Therefore, this worker population may be at increased risk of heat-related illness and/or acute injury during a given shift based on the degree of indoor heat stress. Additional environmental measurements should be collected at these locations among others to further assess the extent of heat stress in this population over an extended time frame; in this way, any potential exposures during peaks in ambient temperature and relative humidity levels would be effectively captured. It is further recommended that staff undergo heat stress training and education to review the signs and symptoms of heat-related illnesses, as well as heat-related illness prevention measures.
The overall average WBGTin for all 10 sites was approximately 25.0˚C (77.0˚F; standard deviation [SD] = 2.0˚C). Action Limits of 28.1°C (82.6°F), 25.0°C (77.0°F), and 23.0°C (73.4°F), expressed as WBGTeff, were calculated for the light, moderate, and heavy work-rate scenarios, respectively. Similarly, TLVs of 30.8°C (87.4°F), 28.2°C (82.8°F), and 26.6°C (79.9°F) were calculated for the light, moderate, and heavy work-rate scenarios, respectively. Regarding the estimated Action Limit, 10% of school kitchens sampled exceeded this recommended limit for the light work-rate scenario, 60% of schools exceeded this limit for the moderate work-rate scenario, and 80% of schools exceeded this limit for the heavy work-rate scenario. For the TLV, none of the kitchens exceeded this limit for the light or moderate work-rate scenarios, while 30% of kitchens were in excess of this limit for the heavy work-rate scenario. Average full-shift CO2 and CO air concentrations ranged from 435 to 911 ppm (mean = 648; SD = 158) and 0.0 to 3.2 ppm (mean = 0.9; SD = 0.9), respectively. These levels were well below AGCIH TLVs for these chemicals, and indicated that sufficient outdoor air exchange was achieved at each sampling site.
Conclusions: Overall, the heat stress and indoor air quality data presented herein suggest that kitchen staff employed in New York City public schools may be exposed to excessive indoor heat levels, depending on their individual work-rate output and degree of heat acclimatization. Therefore, this worker population may be at increased risk of heat-related illness and/or acute injury during a given shift based on the degree of indoor heat stress. Additional environmental measurements should be collected at these locations among others to further assess the extent of heat stress in this population over an extended time frame; in this way, any potential exposures during peaks in ambient temperature and relative humidity levels would be effectively captured. It is further recommended that staff undergo heat stress training and education to review the signs and symptoms of heat-related illnesses, as well as heat-related illness prevention measures.
Primary Topic:
Indoor Environmental Quality/Indoor Air Quality
Secondary Topics:
Exposure Assessment Strategies
Sampling and Analysis
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Acknowledgements and References
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