PCLM-D-23-00028

Considerations for occupational heat exposure: a literature review

PLOS Climate

Dear Dr. Hill,

Thank you for submitting your manuscript to PLOS Climate. After careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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We look forward to receiving your revised manuscript.

Kind regards,

Tarik Benmarhnia, PhD

Academic Editor

PLOS Climate

Journal Requirements:

1. Please provide separate figure files in .tif or .eps format. For more information about figure files please see our guidelines:https://journals.plos.org/climate/s/figures https://journals.plos.org/climate/s/figures#loc-file-requirements 2. We do not publish any copyright or trademark symbols that usually accompany proprietary names, eg  ©, ®, ™  (e.g. next to drug or reagent names). Please remove all instances of trademark/copyright symbols throughout the text, including ® on page 10. 3. Please ensure that the CRediT author contributions listed for every co-author are completed accurately and in full. At this stage, the following Authors require contributions: Lee Hill, Paige Cheveldayoff, Fariha Chowdhury, Nyah Shah, Carly Burow, Melanie Figueiredo, Nikki Nguyen, Meryem Talbo, Roshawn Jamasi, Alexandra Katz, Celina Pasquale. Please ensure that the full contributions of each author are acknowledged in the ""Add/Edit/Remove Authors"" section of our submission form. The list of CRediT author contributions may be found here: https://journals.plos.org/climate/s/authorship#loc-author-contributions 

Additional Editor Comments (if provided):

Thank you for submitting your manuscript to Plos Climate. Your manuscript has been peer-reviewed, and the comments of the two expert reviewers are provided below. While both reviewers highlighted that this is an important and timely topic, they also raised significant concerns that would need to be carefully addressed so we can reassess whether this manuscript is suitable for publication. Importantly, it appears many relevant studies were not included nor discussed in this literature review which needs to be addressed. As a scoping review, it will be also important to clearly follow the PRISMA guidelines (doi:10.7326/M18-0850.)

We look forward to receiving a revised version of your manuscript that carefully addresses these comments.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does this manuscript meet PLOS Climate’s publication criteria? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

Reviewer #2: N/A

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Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #1: No

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: GENERAL COMMENTS

I would like to thank you for having me as a reviewer for this manuscript. The topic of the paper is interesting and fits the scope of the journal. In my opinion, the manuscript could benefit from a deeper analysis as there are many recent studies by the International Labour Organization and the HEAT-SHIELD team that should be considered for discussion. The HEAT-SHIELD project stands as the largest initiative ever undertaken to improve understanding of occupational heat exposure and devise effective solutions to safeguard workers across multiple countries and diverse industries, and therefore it is important to be discussed. For example, lab studies by Piil (Denmark) and Foster (UK) as well as field studies by Ioannou (Southern Europe and Middle East) and colleagues could provide valuable insights on occupational heat exposure for this review.

SPECIFIC COMMENTS

Introduction:

Please consider rephrasing this sentence: ““Heat stress” refers to heat that is accumulated in excess of what the body can tolerate without experiencing significant physiological impairment (7).”

"Heat stress" usually refers to the external factors affecting the body, while "heat strain" refers to the body's internal physiological responses to cope with heat stress.

In occupational settings behavioral mechanisms play the primary role in body temperature regulation. Please consider adding something about behavioral responses.

Background and history:

Since ancient times, there have been recorded instances of occupational heat-related illnesses and fatalities. The HEAT-SHIELD team has published a comprehensive review on this issue, which is available through the following link: https://doi.org/10.1080/23328940.2022.2030634

Physical labour in hot environments:

Please consider mentioning "air velocity"

Protective actions against exposure:

Please have a look at the HEAT-SHIELD series of studies and consider discussing some of them, since there are many more heat-mitigation strategies that worth to be discussed.

A recent ILO/HEAT-SHIELD series of studies were conducted on thermals stress indicators (e.g., WBGT). Please consider discussing those studies as well.

Training and educational programs:

I would like to request that the manuscript be written using the international metric system consistently. Furthermore, recommending a specific water intake protocol of 8 ounces (~250ml) or a glass of water every 15 to 20 minutes may increase the risk of hyponatremia. Hence, I would advise against proposing any water intake guidelines.

Please consider discussing recent ILO/HEAT-SHIELD studies on how white clothing can reduce the adverse impacts of sun exposure on the physiological heat strain experienced by workers.

Fatigue recovery methods and body cooling strategies:

I would recommend including studies conducted in occupational settings in this discussion. It is important to note that athletes typically engage in exercise at much higher intensities (>10 times) than the average worker, and therefore, the findings from studies on athletes may not be directly applicable to occupational settings.

Body Cooling:

Please consider discussing relevant fundings from occupational studies.

Individual Effects:

There are a minimum of 20 inter- and intra-individual factors that can heighten the heat stress/strain encountered by an individual. Further details can be accessed in the HEAT-SHIELD team's recent comprehensive review.

Considerations for current working environments:

Please consider using degrees sign “°” instead of “o” throughout the manuscript.

Reviewer #2: Cheveldayoff et al propose an important review about occupational heat exposure. Under current and future climate changes and increased heat waves intensity, frequency and durations, this topic gained in visibility, so that the topic now appears as an emerging, potentially important occupational and public health topic. Therefore, this review is very timely. The author provides important historic, physiologic, epidemiologic… elements on the topic. However, it appears that, in some sections at least, the articulation of these elements could be improve to facilitate the reading of the paper. Moreover, the paper would gain in clarifying the type of review and/or the method used. Lastly, the paper seems to ignore some important parts of recent literature based on climate change projection. Thereafter, I encourage the author to consider the following comments:

Major comment :

- My main concern regards the method or typology of the review. The author present their work as a scoping review. However, scoping reviews usually provide some elements about literature search and analyse, which are absent of this piece. Therefor, it rather feels that this review is a narrative review. I suggest the authors to clarify and/or update the method they chose for this work, for instance based on the classification proposed by Grant and Booth (https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1471-1842.2009.00848.x)

- P11 mentions fatigue that could results from occupational heat exposure. This fatigue could also result in occupational injuries, an important topic that is not covered by the review, though elements exist (see for instance 10.1016/j.envint.2021.106384). I suggest to include some elements related to these aspects.

- P15 “In Obradovich and Fowler’s model of the effects of warming over the next century on physical activity, a change of +2°C was estimated to lead to an additional six million person-months of physical activity annually in the US (80).”. The study mentioned here seems a bit outdated now, and I fear that a message tailored as it is in that sentence could be misinterpreted and misused to attenuate the global threat that climate change represents, including on occupational health. More recent studies rather suggest that these early estimation were largely underestimated in terms of productivity loss (see https://iopscience.iop.org/article/10.1088/1748-9326/ac3dae or https://www.nature.com/articles/s41467-021-27328-y for instance)

- Regarding projections about occupational heat exposure and health/productivity under climate change, I’m a bit surprised that major pieces of work were not referred in this review. I think specifically to the work done by Luke Parsons (mentioned above) or the modelling study by Andrews et al (10.1016/S2542-5196(18)30240-7)/

- P15: “it is projected that the percentage of total working hours lost will rise to 2.2% in 2030 – a productivity loss equivalent to 80 million full-time jobs.” As mentioned above, more recent studies suggest that current levels of climate change, due to the impact of humid heat, are already causing 150 million full-time job losses” (ref: 10.1088/1748-9326/ac3dae). It would be interesting that the authors comment the discrepancies between both estimates (probably the first estimates accounts only for heat, not humid heat).

Minor comment:

- Introduction: I would suggest to also refer to construction worker early in the introduction, as they represent a specifically exposed category, and a potential important (more important than athletics for instance) and significant one in terms of public/occupational health

- Physical labour in hot environment: the articulation of this part is not so clear. Based on the heading, the scope is expected to be quite general, however, several paragraph are specifically focusing on the role of clothing and/or personal protective equipment. Moreover, the 4th paragraph mentions some organizational factors, such as the kind of remuneration and rest period requirements. All these elements are relevant, but it feels like the structure of this part is not so clear.

- “Early research on Acclimatization”: is it the same author name (Lind) 200y apart?

- “Training and educational program” (p10-11): here again, I would suggest to add a specific paragraph about the construction workers population, due to the large population they represent (if specific literature exist?) , and considering that a large part of the public debate (at least in Europe) during heat waves focuses on this working population.

- Individual effects (p12): wondering whether that part, which mostly describe effects of certain comorbidities such as CVD or diabetes, would not be best suited in p 13 (Chronic/acute health impacts/Considerations for special populations)

- Future consideration: the end of the draft rather suggest that the one massive future consideration is actually climate change. I understand that genetic factors may help better understand individual factors, but I would recommend to reshape this final paragraph in order to better highlight the considerations regarding the physiological/genetic comprehension of heat impact vs. the public health challenges (increase in comorbidities prevalence, climate change…) to mitigate this risk

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Reviewer #1: No

Reviewer #2: Yes: Kévin Jean

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Considerations for occupational heat exposure: a scoping review

PCLM-D-23-00028R1

Dear Dr Hill,

We are pleased to inform you that your manuscript 'Considerations for occupational heat exposure: a scoping review' has been provisionally accepted for publication in PLOS Climate.

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Best regards,

Tarik Benmarhnia, PhD

Academic Editor

PLOS Climate

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Thank you for submitting a revised version of your manuscript. I think the authors did a great job at addressing the comments from the reviewers and the paper is suitable for publication. Congratulations on this great work.

Reviewer Comments (if any, and for reference):