**7. Status of research in occupational heat stress**

The environmental temperature increases day by day to due to the ongoing climate change that is occurring in various part of the world. Deforestation, urban heat island effect, Modernization process, increase in number of industries cause a rise in ambient temperature level, which also has impacts on workers health. Studies pertaining to heat stress across the globe are carried by researchers and they have found that exposure to excessive heat in work place has impacts on workers health and productivity.

Studies in occupational heat stress in India are limited because of the following challenges and constraints [25].


**153**

in India to document the health impacts of heat stress.

*Occupational Heat Stress: A Technical Scan DOI: http://dx.doi.org/10.5772/intechopen.93900*

Specific heat wave events in the Northern hemisphere have been associated with marked short term increases in mortality, with reported excess mortality ranging from 4–142% [4]. It is estimated that in 2003, up to 70,000 additional deaths occurred over the summer months in Western Europe as a consequence of severe heat waves [26]. An estimated 560 extra deaths were observed during the three heat waves of 2002 in Russia. Lag times of just a few days have been observed between the onset of a heat wave and the rise in mortality, suggesting that people succumb quickly to the effects of extreme heat. Some of the deaths occurring in heat waves are due to exacerbation of preexisting illnesses particularly cardiovascular and respiratory diseases, and diseases of the nervous system [27]. Mortality associated with heat waves has been reported to be greatest in city areas, in conjunction with observed high night-time minimum temperatures, high levels of air pollution, and poor housing conditions. Few studies have investigated the effects of extreme hot weather on population morbidity. Hospital admissions have been observed to increase during heat waves. However studies have revealed discrepancies between the impact of heat waves on morbidity and mortality, in terms of magnitude, cause, and age group [28]. Reports of a lesser impact of heat waves on hospital admissions than on mortality may indicate that people die quickly during heat waves before they are able to reach hospital or be noticed by others. Studies of patients admitted to hospitals during heat waves for treatment of heatstroke have shown this illness to be associated with an outcome. The risk of heat stroke among working people is well known and explained by the limits of human physiological adaptability [14]. Significant number of working people dies due to heat stroke even in high income countries as described in a study of agricultural workers in the USA. A substantial amount of body water may be lost as sweat, including loss of fluid through respiration, gastrointestinal tract as well as kidney. Increased dehydration disturbs the homeostasis of the body, leading to decreased skin blood flow, elevated core body temperature, decreased sweat rate leading to impaired to tolerance to work resulting in increased risks of heat injuries. Continuous exposure to excessive heat may cause profound increase in heart rate which may lead to sympatho - vagal imbalance if not treated appropriately [20]. Heart rate is useful in evaluating the exertion required by physical labour in working conditions [22]. Trainings including acclimatization may be useful in maintaining the core body temperature and heart rate within normal range among workers exposed to excessive heat [17]. A wide range of clinical observations & measurements have been used to indicate heat strain, ranging from perception of workers to hospitalization due to heat stroke. > 20% of people are being estimated to have health impacts of heat stress, ranging from skin rash to heat stroke. About 28% of workers were at risk of health impairment due to high heat exposure at work place [29]. There was a noticeable disconnect between worker's perceptions and their ability to perform task [30]. Most of these studies were done in experimental set up which cannot be considered as a standard protocol for studies in field/industry. Some of the examples include rectal temperature, capsule method for core body temperature, nude body weight measurement, etc. Apart from heat, many confounding factors also play a role in health impacts. With all this issues, it is important to identify globally acceptable heat strain parameters and methods. Such methods can be used as relevant indicators locally by the health professionals to develop health surveillance and prevention programs for workers to protect the workers health. There are only few studies done in India about Occupational heat stress and its health impacts and no studies conducted on assessment of heat stress and its physiological responses in this geographical location. So it is very essential to do more studies


#### *Occupational Heat Stress: A Technical Scan DOI: http://dx.doi.org/10.5772/intechopen.93900*

*Occupational Wellbeing*

chronic kidney disease.

increases more than 41°C.

and productivity.

challenges and constraints [25].

employer or worker

d.Study Design

b.Organized vs. Unorganized sector

e.Assessment of health parameters

**7. Status of research in occupational heat stress**

nature, they often relate to how you feel. Exposure to more heat stress for a longer duration can cause health problems which impair workers' ability to execute the task and may cause adverse health effects [10]. The body temperature increases because of internal heat production during muscular activity in work place. If the ambient temperature is more than the body temperature, then the heat loss from the body will be minimized by conduction, convection, radiation. As a result the core body temperature will keep increasing and may result in heat related illness such as heat rash, heat syncope, heat exhaustion, heat stroke. The heart rate also increases to pump more blood through skin so that excess heat can be lost to the environment through sweating [14]. These changes will cause additional load on the body. Changes in blood flow and excessive sweating will lead to decrease in person's ability to do physical and mental work [8]. When the environmental temperature rises above 30°C, it may interfere with the performance of mental tasks [14]. The occupational heat stress can affect the workers health either directly or indirectly. The direct health impacts include the heat related illness such as heat rash, heat syncope, heat edema, heat exhaustion and heat stroke [6, 14]. The indirect health impacts include physical and mental stress, hypertension, diabetes mellitus and

Heat rashes are the red spots on the skin which cause a prickling sensation during heat exposure. Heat edema is swelling which generally occurs among people who are not acclimatized to working in hot conditions. Heat cramps are sharp pains in the muscles that may occur as a result of salt imbalance resulting from the failure to replace salt lost due to sweating. Heat exhaustion is caused by excessive loss of body water and salt through excessive sweating. Heat syncope is heat-induced giddiness and fainting because of insufficient flow of blood to the brain while a person is standing which is caused by the loss of body fluids through sweating. Heat stroke is the most serious types of heat illnesses. The body temperature often

The environmental temperature increases day by day to due to the ongoing climate change that is occurring in various part of the world. Deforestation, urban heat island effect, Modernization process, increase in number of industries cause a rise in ambient temperature level, which also has impacts on workers health. Studies pertaining to heat stress across the globe are carried by researchers and they have found that exposure to excessive heat in work place has impacts on workers health

Studies in occupational heat stress in India are limited because of the following

c.Improper record/documentation of heat/any occupational disease by the

a.Permission from Industries to collect data and to publish it

**152**

Specific heat wave events in the Northern hemisphere have been associated with marked short term increases in mortality, with reported excess mortality ranging from 4–142% [4]. It is estimated that in 2003, up to 70,000 additional deaths occurred over the summer months in Western Europe as a consequence of severe heat waves [26]. An estimated 560 extra deaths were observed during the three heat waves of 2002 in Russia. Lag times of just a few days have been observed between the onset of a heat wave and the rise in mortality, suggesting that people succumb quickly to the effects of extreme heat. Some of the deaths occurring in heat waves are due to exacerbation of preexisting illnesses particularly cardiovascular and respiratory diseases, and diseases of the nervous system [27]. Mortality associated with heat waves has been reported to be greatest in city areas, in conjunction with observed high night-time minimum temperatures, high levels of air pollution, and poor housing conditions. Few studies have investigated the effects of extreme hot weather on population morbidity. Hospital admissions have been observed to increase during heat waves. However studies have revealed discrepancies between the impact of heat waves on morbidity and mortality, in terms of magnitude, cause, and age group [28]. Reports of a lesser impact of heat waves on hospital admissions than on mortality may indicate that people die quickly during heat waves before they are able to reach hospital or be noticed by others. Studies of patients admitted to hospitals during heat waves for treatment of heatstroke have shown this illness to be associated with an outcome. The risk of heat stroke among working people is well known and explained by the limits of human physiological adaptability [14]. Significant number of working people dies due to heat stroke even in high income countries as described in a study of agricultural workers in the USA. A substantial amount of body water may be lost as sweat, including loss of fluid through respiration, gastrointestinal tract as well as kidney. Increased dehydration disturbs the homeostasis of the body, leading to decreased skin blood flow, elevated core body temperature, decreased sweat rate leading to impaired to tolerance to work resulting in increased risks of heat injuries. Continuous exposure to excessive heat may cause profound increase in heart rate which may lead to sympatho - vagal imbalance if not treated appropriately [20]. Heart rate is useful in evaluating the exertion required by physical labour in working conditions [22]. Trainings including acclimatization may be useful in maintaining the core body temperature and heart rate within normal range among workers exposed to excessive heat [17]. A wide range of clinical observations & measurements have been used to indicate heat strain, ranging from perception of workers to hospitalization due to heat stroke. > 20% of people are being estimated to have health impacts of heat stress, ranging from skin rash to heat stroke. About 28% of workers were at risk of health impairment due to high heat exposure at work place [29]. There was a noticeable disconnect between worker's perceptions and their ability to perform task [30]. Most of these studies were done in experimental set up which cannot be considered as a standard protocol for studies in field/industry. Some of the examples include rectal temperature, capsule method for core body temperature, nude body weight measurement, etc. Apart from heat, many confounding factors also play a role in health impacts. With all this issues, it is important to identify globally acceptable heat strain parameters and methods. Such methods can be used as relevant indicators locally by the health professionals to develop health surveillance and prevention programs for workers to protect the workers health. There are only few studies done in India about Occupational heat stress and its health impacts and no studies conducted on assessment of heat stress and its physiological responses in this geographical location. So it is very essential to do more studies in India to document the health impacts of heat stress.
