Field-based evaluation of hand–arm vibration (HAV) and heat exposure among grounds maintenance workers in the southeastern United States: a pilot study

The purpose of this pilot study was to evaluate simultaneous exposure to hand-arm vibration (HAV) and heat among grounds maintenance workers. Ten groundskeepers employed at a southern US institution were recruited. Individual workers’ exposure to HAV and heat was monitored during their regular work shift for three days. HAV exposure was measured using tri-axial vibration dosimeters worn on both hands of the participants to obtain daily vibration exposure (A(8)) and vibration total value (a hv ) for each power tool used. Daily HAV exposure dose was determined using a hv for all tools used and corresponding tool operation duration. Lifetime cumulative HAV exposure dose (a hv−lifetime ) was determined based on a hv for all tools used and exposure history obtained from a questionnaire. Personal heat exposure was evaluated using a wearable device to collect estimated core body temperature (CBT). Environmental heat metrics, including heat index (HI) and wet bulb globe temperature (WBGT), were determined using a WBGT monitor. Environmental parameters, including ambient temperature, relative humidity, and solar radiation, were also measured using a portable weather station. Mean A(8) values of the ten individual workers ranged from 0.8 to 3.3 m/s 2 for the right hand and 0.7 to 2.9 m/s 2 for the left hand. Tool-specific mean a hv ranged from 2.3 to 4.8 m/s 2 for the right hand and 2.6 to 6.2 m/s 2 for the left hand. The daily HAV exposure dose ranged from 6.2 to 23.7 m/s 2 for the right hand and from 4.6 to 23.4 m/s 2 for the left hand. The a hv−lifetime range was 1,128.5 to 172,333.0 and 1,102.4 to 161,462.6 h∙m/s 2 for the right and left hands, respectively. The daily mean of estimated CBT of the individual workers ranged from 36.7 to 39.1 °C. The daily mean HI and WBGT values were from 20.7 to 48.9 °C and from 17.5 to 37.5 °C, respectively. The average ambient temperature, relative humidity, and solar radiation were 30.3 ± 4.1 °C, 59.9 ± 14.5%, and 217.8 ± 248.5 W/m 2 , respectively. One groundskeeper’s three-day average A(8) exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) action limit (AL) of 2.5 m/s 2 . During the three-day full-time shift, 19.0% of total work hours exceeded the upper normal CBT range of 38 °C, and 66.0 and 65.4% of total work hours were at or above the Occupational Safety and Health Administration (OSHA)’s proposed high heat trigger for HI (32.2 °C) and WBGT (26.7 °C for heavy workload), respectively. These findings indicate that continuous monitoring for heat strain is needed for outdoor workers whose jobs require a high workload especially under the southeastern US summer climate.