Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Industrial and Managements Systems Engineering

Committee Chair

Gary Winn

Committee Member

Ashish Nimbarte

Committee Member

Bassam Atieh

Committee Member

Jeremy Gouzd

Committee Member

Kenneth Currie


Outdoor workers have an increased risk of heat stress in Saudi Arabia since it is one of the hottest places in the Middle East. Recently, the government decided to limit outdoor work hours during the months of June, July, and August every year, and banned working under the direct sunlight from 12:00 to 03:00 p.m., although outdoor workers in the petroleum, natural gas, or emergency maintenance work industries are exempt from this prohibition. Traditionally, the efforts by safety and health professionals to mitigate work-related heat injury has been directed toward the assessment of environmental heat stress (e.g., wet-bulb globe temperature), rather than toward the associated physiological strain responses (e.g., heart rate and core temperatures). However, because a worker’s physiological response to given heat stress is modified independently by individual factors of each worker (e.g., age, sex, chronic disease, others), it becomes challenging to protect workers on an individual basis from heat-related injury without assessing those physiological responses.

The primary objective of this study was to examine whether limiting work hours will reduce the risk of heat stress among outdoor workers or not. That can be achieved by (1) examining if the ban on three-month midday outdoor work needs to be extended to cover the period from June 1st to September 30th (2) examining if the midday break between 12:00 pm and 03:00 pm need to be extended by a few more hours.

A field study was carried out in Dammam City on Saudi Arabia’s eastern coast where the humidity reaches 95% and temperature can reach 47°C (116.6°F) during summer months. The core temperature of 20 subjects matched for age, gender, and experience subjects was monitored while they performed their normal duties in the outdoor environment of Dammam City. The core temperature of these outdoor workers was measured using a novel non-invasive measurement method.

The obtained results showed that subjects were under the risk of heat stress over a large part of the workday and their body temperature exceeds the allowable core temperature (38.5°C; 101.3°F) which the ACGIH has proposed to protect workers from experiencing heat stress. The intensity of exposure was high from (10:00-12:00 a.m.) that is not included in the midday break. A control group (non-policy) which did not experience the mid-day break showed essentially the same core body temperature as the experimental (policy) group.

Among chief findings was that complying with a midday break work ban (12:00–3:00 p.m.) was not effective in reducing heat stress risk under the conditions and limitations of the design. The policymakers should be informed that this particular policy is not helpful and does not significantly lower core body temperatures. Some policy modifications are suggested which might better impact core body temperatures under these extreme conditions.