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=== Acclimatization ===
=== Acclimatization ===
According to the [[National Institute for Occupational Safety and Health]] (NIOSH), [[acclimatization]] is a biological process that an individual will go through to adjust to a stimulus following continued exposure.<ref name=":03">{{Cite web|date=2020-02-20|title=Heat Stress Acclimatization {{!}} NIOSH {{!}} CDC|url=https://www.cdc.gov/niosh/topics/heatstress/acclima.html|access-date=2020-11-03|website=www.cdc.gov|language=en-us}}</ref> Physiologically, acclimatization to heat will allow a worker’s body to more efficiently cool itself when exposed to high temperatures. When a worker has adjusted to working in a hotter environment, they will have a lower [[heart rate]], earlier onset of [[Perspiration|sweating]], and increased blood flow to blood [[Blood vessel|vessel]]<nowiki/>s near the skin, allowing their body to more efficiently cool itself than a worker who is not acclimatized.<ref name=":03" /><ref name=":12">{{Cite journal|date=2016-02-01|title=Criteria for a recommended standard: occupational exposure to heat and hot environments - revised criteria 2016.|url=https://www.cdc.gov/niosh/docs/2016-106/|language=en|doi=10.26616/nioshpub2016106}}</ref> See below section on Acclimatization Schedules.[[File:Residential construction worker (9256407214).jpg|thumb|Construction Worker]]
According to the [[National Institute for Occupational Safety and Health]] (NIOSH), [[acclimatization]] is a biological process that an individual will go through to adjust to a stimulus following continued exposure.<ref name=":03">{{Cite web|date=2020-02-20|title=Heat Stress Acclimatization {{!}} NIOSH {{!}} CDC|url=https://www.cdc.gov/niosh/topics/heatstress/acclima.html|access-date=2020-11-03|website=www.cdc.gov|language=en-us}}</ref> Physiologically, acclimatization to heat will allow a worker’s body to more efficiently cool itself when exposed to high temperatures. When a worker has adjusted to working in a hotter environment, they will have a lower [[heart rate]], earlier onset of [[Perspiration|sweating]], and increased blood flow to blood [[Blood vessel|vessel]]<nowiki/>s near the skin, allowing their body to more efficiently cool itself than a worker who is not acclimatized.<ref name=":03" /><ref name=":12">{{Cite journal|date=2016-02-01|title=Criteria for a recommended standard: occupational exposure to heat and hot environments - revised criteria 2016.|url=https://www.cdc.gov/niosh/docs/2016-106/|language=en|doi=10.26616/nioshpub2016106}}</ref> See below section on [[Occupational heat stress#Acclimatization Schedules|Acclimatization Schedules]] for specific processes.[[File:Residential construction worker (9256407214).jpg|thumb|Construction Worker]]


== Examples of high risk occupations ==
== Examples of high risk occupations ==
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All employees should be trained to recognize the symptoms of [[Hyperthermia|heat stress]].<ref name=":5" /> Supervisors should monitor their employees throughout the day for these symptoms and, for larger teams, a buddy system can be used to group workers to monitor each other for signs of heat illness.<ref name=":24" /> Additionally, informing workers about their working conditions and risk of heat illness is important, specifically in making sure that everyone understands what the heat index means and what extra precautions to take during higher risk periods.<ref>{{Cite web|title=OSHA's Campaign to Prevent Heat Illness in Outdoor Workers {{!}} Using the Heat Index {{!}} Occupational Safety and Health Administration|url=https://www.osha.gov/SLTC/heatillness/heat_index/|access-date=2020-11-10|website=www.osha.gov}}</ref>
All employees should be trained to recognize the symptoms of [[Hyperthermia|heat stress]].<ref name=":5" /> Supervisors should monitor their employees throughout the day for these symptoms and, for larger teams, a buddy system can be used to group workers to monitor each other for signs of heat illness.<ref name=":24" /> Additionally, informing workers about their working conditions and risk of heat illness is important, specifically in making sure that everyone understands what the heat index means and what extra precautions to take during higher risk periods.<ref>{{Cite web|title=OSHA's Campaign to Prevent Heat Illness in Outdoor Workers {{!}} Using the Heat Index {{!}} Occupational Safety and Health Administration|url=https://www.osha.gov/SLTC/heatillness/heat_index/|access-date=2020-11-10|website=www.osha.gov}}</ref>


=== '''Acclimatization Schedule''' ===
=== '''Acclimatization Schedules''' ===
Acclimatization can occur over different time periods for different people, but NIOSH recommends allowing workers to be exposed to gradually higher levels of heat over 7-14 days for acclimatization. New workers without recent exposure to heat may require additional time to adjust.<ref name=":03" /> On the first day of an acclimatization process, workers without previous heat exposure should be asked to complete, at most, 20% of their typical workday. After this, their workload can increase by 20% for each day of the process.<ref name=":03" /> For workers with previous exposure working in high temperature settings, acclimatization can occur as fast as four days, starting with workers completing 50% of their typical work duration on the first day.<ref name=":03" /> NIOSH strongly suggests that workers who are currently adjusting to new conditions should be supervised closely for signs of [[Hyperthermia|heat stress]], especially those who may adjust slower due to age, pre-existing health conditions, or lower levels of [[physical fitness]].<ref name=":23">{{Cite web|date=2020-02-20|title=Heat Stress Recommendations {{!}} NIOSH {{!}} CDC|url=https://www.cdc.gov/niosh/topics/heatstress/recommendations.html|access-date=2020-11-03|website=www.cdc.gov|language=en-us}}</ref> A worker’s level of acclimatization must also be maintained, and if workers are absent from the working conditions for more than a week, they will need to begin the acclimatization process again.<ref name=":03" /><ref name=":23" />
Acclimatization can occur over different time periods for different people, but NIOSH recommends allowing workers to be exposed to gradually higher levels of heat over 7-14 days for acclimatization. New workers without recent exposure to heat may require additional time to adjust.<ref name=":03" /> On the first day of an acclimatization process, workers without previous heat exposure should be asked to complete, at most, 20% of their typical workday. After this, their workload can increase by 20% for each day of the process.<ref name=":03" /> For workers with previous exposure working in high temperature settings, acclimatization can occur as fast as four days, starting with workers completing 50% of their typical work duration on the first day.<ref name=":03" /> NIOSH strongly suggests that workers who are currently adjusting to new conditions should be supervised closely for signs of [[Hyperthermia|heat stress]], especially those who may adjust slower due to age, pre-existing health conditions, or lower levels of [[physical fitness]].<ref name=":23">{{Cite web|date=2020-02-20|title=Heat Stress Recommendations {{!}} NIOSH {{!}} CDC|url=https://www.cdc.gov/niosh/topics/heatstress/recommendations.html|access-date=2020-11-03|website=www.cdc.gov|language=en-us}}</ref> A worker’s level of acclimatization must also be maintained, and if workers are absent from the working conditions for more than a week, they will need to begin the acclimatization process again.<ref name=":03" /><ref name=":23" />


Revision as of 23:30, 10 November 2020

Occupational heat stress is the net load to which a worker is exposed from the combined contributions of metabolic heat, environmental factors, and clothing worn which results in an increase in heat storage in the body. [1]Heat stress can result in heat-related illnesses, such as heat stroke, hyperthermia, heat exhaustion, heat cramps or heat rashes.[2] Although heat exhaustion is less severe, hyperthermia is a medical emergency and requires emergency treatment, which if not provided can even lead to death.[3]

Heat stress causes illness but also may account for an increase in workplace accidents, and a decrease in worker productivity.[4] Worker injuries attributable to heat include those caused by: sweaty palms, fogged-up safety glasses, and dizziness.[2] Burns may also occur as a result of accidental contact with hot surfaces or steam. In the United States, occupational heat stress is becoming more significant as the average temperatures increase but remains overlooked. There are few studies and regulations regarding heat exposure of workers.[5]

Risk factors

Heat-related illnesses from occupational heat stress is impacted by multiple factors. Workers exposed to high temperatures, humidity, and limited air movement, especially outside workers, are vulnerable to heat illness.[5][6] Physiologic factors can also impact a worker's vulnerability, specifically if their job requires physical exertion, which produces metabolic heat.[5][7] Workers can also be more vulnerable to heat illness if they are dehydrated from sweating and not drinking enough water or have a low level of physical fitness.[6] Certain pre-existing health conditions and medications can also make it more difficult for someone to adapt to high temperatures, as can pregnancy.[6] Additionally, wearing heavy or thick personal protective equipment and clothing can prevent workers from sweating properly, which prevents the body from effectively cooling.[8] Workers can also adjust to working in high temperatures so their bodies can become better at cooling over time, though this adjustment requires a multi-week acclimatization process.

Acclimatization

According to the National Institute for Occupational Safety and Health (NIOSH), acclimatization is a biological process that an individual will go through to adjust to a stimulus following continued exposure.[9] Physiologically, acclimatization to heat will allow a worker’s body to more efficiently cool itself when exposed to high temperatures. When a worker has adjusted to working in a hotter environment, they will have a lower heart rate, earlier onset of sweating, and increased blood flow to blood vessels near the skin, allowing their body to more efficiently cool itself than a worker who is not acclimatized.[9][10] See below section on Acclimatization Schedules for specific processes.

Construction Worker

Examples of high risk occupations

Workers in many occupations are at high risk for exposure to heat stress. Some of the higher risk occupations include firefighter, bakery worker, miner, military personnel,[4] construction worker, factory worker, boiler room worker, landscaper, some athletes and agricultural worker.[11][2]

Symptoms of heat stress

The main symptoms of heat stress are perspiration, increased heart rate, and dehydration.[12] Other general symptoms include painful muscle cramps, extreme weakness, nausea, dizziness, headache, breathing fast and clammy, pale, cool, and/or moist skin or red, dry skin. [13]

Measurement and Monitoring

Measurements

NIOSH has set Recommended Alert Limits (RALs) and Recommended Exposure Limits (RELs) for employers and employees to use in determining, monitoring, and responding to their risk of heat exposure and related impacts.[14] While different ranges of temperatures are used to determine what types of protective action should be implemented, there is no universal safe limit applied across all occupational settings. This is because safety will depend on factors specific to the environments and tasks of a specific job, as well as the workers’ physical health and fitness.[15]

There are many different ways to measure temperature. Typically, a thermometer can be used to measure environmental temperature. However, high humidity, or the amount of water that has evaporated into the air in the form of water vapor, can often make the temperature outside feel hotter than the measured temperature.[16] To address this, a heat index measure includes the air’s relative humidity, or a measure of how much moisture is in the air compared to if the air were saturated with water vapor. This measure of humidity along with temperature provides more information on what workers should expect to feel in terms of heat if working outside.[16]

Additionally, some sources also report wet-bulb temperature, which is considered an informative measure for individuals who will be working in direct sunlight.[17] This measure takes into account both temperature and humidity, but also includes measures of wind speed, cloud cover, and angle of the sun at different times of the day.[17]

OSHA uses a measure called the Adjusted Air Temperature to determine how often workers should be monitored, which involves the equation:[18]

Where T is temperature measured in degrees Fahrenheit (°F) and percent sunshine is measured on a spectrum from 100% (no clouds, noticeable shadows) to 0% (total cloud cover, no shadows).[18]

Monitoring

OSHA recommends monitoring worker's heart rate, temperature, and body water loss throughout shifts in hot conditions.[18] When the adjusted temperature is 90°F or above, it is recommended that even healthy, acclimatized workers have these measures monitored every 45 minutes. Workers who are not acclimatized or who are wearing impermeable equipment or clothing should be monitored every 15 minutes.[18]

NIOSH and OSHA have also created a Heat Index App for mobile devices that provides information on temperature, humidity, risk of heat illness, as well as hourly forecasts of temperature and information on how to prevent and treat heat illnesses.[19]

Prevention

Employers can establish prevention programs, which focus on having protocols to gradually increases workloads and concede on allowing on more breaks for new hired workers. [20] Employers can control heat stress through engineering controls, work practices, providing training, implementing an acclimatization schedule, providing water and encouraging workers to drink often, and ensuring workers take appropriate rest breaks to cool down.[21]

Engineering Controls

Employers can provide air conditioners for indoor work spaces and for indoor break areas. Fans can also be used together with air conditioners, and misting fans can be used outside for added cooling. Additionally, increasing building ventilation and improving the insulation of hot surfaces will reduce indoor temperatures.[22] If all work is completed outdoors, a shaded area should be provided with ample water for workers to take breaks often.[23]

Work Practices

Ample breaks with space provided in shaded or cooled areas are important for preventing heat stress related illnesses. Employers should also supply water for workers throughout the day, as workers need to drink more water when working in hot environments than they would otherwise.[24] Additionally, on particularly hot days, limiting high-exertion tasks as much as possible is important for keeping a worker’s metabolic temperature down.[25]

Training

All employees should be trained to recognize the symptoms of heat stress.[2] Supervisors should monitor their employees throughout the day for these symptoms and, for larger teams, a buddy system can be used to group workers to monitor each other for signs of heat illness.[25] Additionally, informing workers about their working conditions and risk of heat illness is important, specifically in making sure that everyone understands what the heat index means and what extra precautions to take during higher risk periods.[26]

Acclimatization Schedules

Acclimatization can occur over different time periods for different people, but NIOSH recommends allowing workers to be exposed to gradually higher levels of heat over 7-14 days for acclimatization. New workers without recent exposure to heat may require additional time to adjust.[9] On the first day of an acclimatization process, workers without previous heat exposure should be asked to complete, at most, 20% of their typical workday. After this, their workload can increase by 20% for each day of the process.[9] For workers with previous exposure working in high temperature settings, acclimatization can occur as fast as four days, starting with workers completing 50% of their typical work duration on the first day.[9] NIOSH strongly suggests that workers who are currently adjusting to new conditions should be supervised closely for signs of heat stress, especially those who may adjust slower due to age, pre-existing health conditions, or lower levels of physical fitness.[27] A worker’s level of acclimatization must also be maintained, and if workers are absent from the working conditions for more than a week, they will need to begin the acclimatization process again.[9][27]

Occupational standards

International

International Organization for Standardization helps set standards for monitoring environments, analyzing data, and interpreting results.[28]

United States

Section 5(a)(1) of the Occupational Safety and Health Act of 1970 declares that "Each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees."[5][29]

The Mine Safety and Health Administration provides guidelines and recommendations to employers for preventing heat stress among workers. There guidelines and recommendations are not enforced regulations, but instead completely voluntary.[5][30]

National Institute for Occupational Safety and Health (NIOSH) conducts research on occupational hazards such as heat stress in order to provide better intervention methods and protect workers.[2]

Only three of the fifty states have created worker regulations regarding heat: California, Washington, and Minnesota.[5] California Code of Regulations states that employers of high risk outdoor workers are entitled to protection against heat. The employer must provide access to water and shade, practice high heat procedures, practice emergency response procedures, and practice acclimatization methods.[5][11] Washington State Legislature states that employers of high risk outdoor workers follow regulations to prevent heat stress.[5] Minnesota Administrative Rules state that indoor ventilation and temperature are regulated to prevent heat stress.[5]

"Protect Your Workers From Heat Stress", CDC

Beginning in 1972, NIOSH published a recommended standard for hot work environments, and has periodically revised to take new scientific findings into account.[31] The intent of the NIOSH Recommended Standard for Occupational Exposure to Heat and Hot Environments is to prevent injury, disease, death, and reduced productivity.[31] The recommendations include workplace limits and surveillance, medical monitoring, surveillance of heat-related sentinel health events, posting of hazardous areas, protective clothing and equipment, worker information and training, control of heat stress, and record keeping.[31]

Control of heat stress

Control of heat stress has recommended general requirements, engineering controls, work and hygienic practices, and a heat alert program.[31]

General Requirements

NIOSH recommends that every employer should create and implement a written program aimed at reducing heat exposures. Engineering and work practice controls should be used to reduce exposures, and a heat alert program should be implemented.[31]

Engineering Controls

Air temperatures should be reduced so it does not exceed skin temperatures. Radiant heat should be reduced by creating barriers around the source. Evaporative heat loss can be increased by increasing air movement around the worker.[31]

Work and Hygienic Practices

The time workers spend in hot environments should be limited, with an increase of recovery time spent in cool environments. Use of more efficient procedures and tools is beneficial to reducing metabolic demands of the job. Heat tolerance may be increased by implementing a heat tolerance plan and increasing physical fitness. Employees should be trained to recognize and treat the early signs and symptoms of heat illnesses, and employers should provide cool water for employees.[31]

Heat Alert Program

Heat alert programs should be developed for implementation when hotter than normal temperatures, or a heat wave occurs.[31]

References

  1. ^ "NIOSH Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments". 2016. doi:10.26616/NIOSHPUB2016106. {{cite journal}}: Cite journal requires |journal= (help)
  2. ^ a b c d e "CDC - Heat Stress - NIOSH Workplace Safety and Health Topic". www.cdc.gov. Retrieved 2016-04-15.
  3. ^ "CDC - Heat Stress - Heat Related Illness - NIOSH Workplace Safety and Health Topic". www.cdc.gov. Retrieved 2016-03-21.
  4. ^ a b Lucas, Rebekah A I; Epstein, Yoram; Kjellstrom, Tord (2014-07-23). "Excessive occupational heat exposure: a significant ergonomic challenge and health risk for current and future workers". Extreme Physiology & Medicine. 3 (1): 14. doi:10.1186/2046-7648-3-14. PMC 4107471. PMID 25057350.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  5. ^ a b c d e f g h i Gubernot, Diane M.; Anderson, G. Brooke; Hunting, Katherine L. (2013-12-11). "The epidemiology of occupational heat exposure in the United States: a review of the literature and assessment of research needs in a changing climate". International Journal of Biometeorology. 58 (8): 1779–1788. doi:10.1007/s00484-013-0752-x. ISSN 0020-7128. PMC 4145032. PMID 24326903.
  6. ^ a b c CDC (2020-08-31). "NIOSH Heat Stress Topic Page". Centers for Disease Control and Prevention. Retrieved 2020-11-03.
  7. ^ "Heat Stress in the Workplace | Environmental Health and Safety | Iowa State University". www.ehs.iastate.edu. Retrieved 2020-11-10.
  8. ^ "Heat Stress Recommendations | NIOSH | CDC". www.cdc.gov. 2020-02-20. Retrieved 2020-11-03.
  9. ^ a b c d e f "Heat Stress Acclimatization | NIOSH | CDC". www.cdc.gov. 2020-02-20. Retrieved 2020-11-03.
  10. ^ "Criteria for a recommended standard: occupational exposure to heat and hot environments - revised criteria 2016". 2016-02-01. doi:10.26616/nioshpub2016106. {{cite journal}}: Cite journal requires |journal= (help)
  11. ^ a b "California Code of Regulations, Title 8, section 3395 Heat Illness Prevention". www.dir.ca.gov. Retrieved 2016-03-21.
  12. ^ Aastrand, Irma (1975). "Heat Stress in Occupational Work". Royal Swedish Academy of Sciences and Springer.
  13. ^ "Heat Illness Prevention - Title 8 Section 3395". www.dir.ca.gov. Retrieved 2016-05-10.
  14. ^ "Criteria for a recommended standard: occupational exposure to heat and hot environments - revised criteria 2016". 2016-02-01. doi:10.26616/nioshpub2016106. {{cite journal}}: Cite journal requires |journal= (help)
  15. ^ "Heat Stress Monitoring". OHSA Occupational Health Services Australia. Retrieved 2020-11-03.
  16. ^ a b US Department of Commerce, NOAA. "Heat Index". www.weather.gov. Retrieved 2020-11-03.
  17. ^ a b US Department of Commerce, NOAA. "WetBulb Globe Temperature". www.weather.gov. Retrieved 2020-11-03.
  18. ^ a b c d "OSHA's Campaign to Prevent Heat Illness in Outdoor Workers | Using the Heat Index - Monitoring Workers at Risk of Heat-related Illness | Occupational Safety and Health Administration". www.osha.gov. Retrieved 2020-11-03.
  19. ^ "OSHA-NIOSH Heat Safety Tool App | NIOSH | CDC". www.cdc.gov. 2020-02-20. Retrieved 2020-11-03.
  20. ^ "OSHA's Campaign to Prevent Heat Illness in Outdoor Workers". www.osha.gov. Retrieved 2016-05-10.
  21. ^ "CDC - Heat Stress - Recommendations - NIOSH Workplace Safety and Health Topic". www.cdc.gov. Retrieved 2017-02-01.
  22. ^ "Safety and Health Topics | Heat - Prevention - Engineering Controls, Work Practices, and Personal Protective Equipment | Occupational Safety and Health Administration". www.osha.gov. Retrieved 2020-11-03.
  23. ^ "OSHA's Campaign to Prevent Heat Illness in Outdoor Workers | Using the Heat Index | Occupational Safety and Health Administration". www.osha.gov. Retrieved 2020-11-03.
  24. ^ CDC (2020-08-31). "NIOSH Heat Stress Topic Page". Centers for Disease Control and Prevention. Retrieved 2020-11-03.
  25. ^ a b "Heat Stress Recommendations | NIOSH | CDC". www.cdc.gov. 2020-02-20. Retrieved 2020-11-03.
  26. ^ "OSHA's Campaign to Prevent Heat Illness in Outdoor Workers | Using the Heat Index | Occupational Safety and Health Administration". www.osha.gov. Retrieved 2020-11-10.
  27. ^ a b "Heat Stress Recommendations | NIOSH | CDC". www.cdc.gov. 2020-02-20. Retrieved 2020-11-03.
  28. ^ Parsons, Ken (2013-01-01). "Occupational Health Impacts of Climate Change: Current and Future ISO Standards for the Assessment of Heat Stress". Industrial Health. 51 (1): 86–100. doi:10.2486/indhealth.2012-0165. PMID 23411759.
  29. ^ "OSHA Content Document". www.osha.gov. Retrieved 2016-03-21.
  30. ^ "Heat Stress - Safety Manual Number 6". arlweb.msha.gov. Archived from the original on 2016-03-07. Retrieved 2016-03-21.
  31. ^ a b c d e f g h "CDC - Occupational Exposure to Heat and Hot Environments - NIOSH Publications & Products". www.cdc.gov. 2016. doi:10.26616/NIOSHPUB2016106. Retrieved 2016-04-21.
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