Published 27 June 2026 • By Dr. Megan Tranter
Industrial hygiene has always been about anticipating, recognizing, evaluating, and controlling workplace hazards. Climate change is now reshaping all four of those steps at once. The hazards we already manage (heat, ultraviolet radiation, air pollution, biological agents) are intensifying, lengthening their seasons, and spreading into regions and occupations that never had to think about them. The International Labour Organization estimates that more than 70 percent of the global workforce is now exposed to climate-related health hazards. This post takes a horizon-scanning view of how a warming, more volatile climate is changing the practice of occupational health and what the profession must do to keep pace.
What You’ll Learn
- The scale of climate-related occupational risk from the ILO 2024 report
- What the Lancet Countdown documents about heat, labor, and health
- How hazard ranges are expanding geographically and seasonally
- The interacting hazards beyond heat: wildfire smoke, UV, vector-borne disease, and agrochemicals
- How industrial hygiene practice and standards must adapt
Introduction
The relationship between climate change and occupational health is direct and measurable. Workers are the population most exposed to outdoor conditions for the longest periods, often performing physically demanding tasks that generate metabolic heat in addition to environmental heat. As global temperatures rise, the hazards that industrial hygienists evaluate are not merely getting worse in intensity; they are changing in character, timing, and distribution. A foundry has always been hot, but now the surrounding region is hotter for more of the year; outdoor crews face longer wildfire-smoke seasons; and disease vectors are appearing in latitudes where they were previously rare. Understanding these shifts is essential to anticipating tomorrow’s exposures rather than merely reacting to today’s.
The ILO 2024 Report: A Cocktail of Hazards
In April 2024, the International Labour Organization released “Ensuring safety and health at work in a changing climate,” accompanied by a detailed report on heat at work. Its findings are sobering. More than 2.4 billion workers (over 70 percent of the global workforce) are likely to be exposed to excessive heat at some point during their work, a proportion that has risen from 65.5 percent in 2000 to 70.9 percent. The ILO attributes roughly 18,970 work-related deaths and around 23 million occupational injuries each year to excessive heat alone. Crucially, the report frames climate change as producing a “cocktail” of simultaneous hazards: heat, ultraviolet radiation, extreme weather events, air pollution, vector-borne diseases, and agrochemicals, often affecting the same workers at the same time. Regional exposure is starkly unequal, with Africa, the Arab states, and Asia-Pacific bearing the highest burdens. This reframing matters for practice: a hazard-by-hazard assessment can miss the compounded risk a worker actually faces.
The Lancet Countdown: Heat, Labor, and Mortality
The Lancet Countdown on health and climate change tracks dozens of indicators annually, and its labor and heat metrics translate climate into human and economic terms. The 2024 report documented a record loss of about 512 billion potential labor hours globally in 2023 due to heat exposure, with an estimated 835 billion US dollars in associated income losses. In the United States alone, roughly 3.4 billion potential labor hours were lost to heat in 2023, an increase of about 69 percent over the 1990s baseline. The report also recorded that heat-related mortality among people older than 65 rose by a record-breaking margin compared with the 1990s. These figures are not abstractions; they represent agricultural, construction, and outdoor service workers whose productivity, income, and health are being eroded by conditions that already exceed safe-work thresholds for parts of the day in many regions.
Expanding Hazard Ranges
One of the most consequential shifts for industrial hygiene is the geographic and seasonal expansion of hazards. Heat-stress days that once arrived only in midsummer now begin in spring and persist into autumn, lengthening the window in which work-rest scheduling and acclimatization must be enforced and catching employers who treat heat as a brief seasonal nuisance. Wildfire smoke, once a regional concern of the western United States, now blankets large areas far downwind for days at a time, exposing outdoor and even indoor workers to fine particulate matter, a problem explored in the post on wildfire smoke and the outdoor workforce. Ground-level ultraviolet radiation and the cumulative skin-cancer risk it drives are a growing concern for the expanding outdoor workforce, as covered in the post on ultraviolet radiation and outdoor workers. Disease vectors such as ticks and mosquitoes are extending their ranges poleward and to higher elevations, bringing Lyme disease, West Nile virus, and other vector-borne illnesses to workforces with no prior experience managing them. Each of these expansions forces hazard recognition into places and seasons where it was previously unnecessary.
Chronic and Emerging Health Effects
Beyond acute heat illness, sustained occupational heat exposure is now recognized as a driver of chronic disease. As the climate warms, the conditions that produce this nephropathy will affect more workers in more regions. Heat also interacts with chemical exposures: higher temperatures increase the volatility and dermal absorption of many solvents and pesticides, and physical exertion in heat increases minute ventilation, thereby increasing the inhaled dose of airborne contaminants. These interactions mean that occupational exposure limits derived under temperate laboratory conditions may understate real-world risk in a hotter world, with direct implications for how we set and apply them.
Adapting Industrial Hygiene Practice
NIOSH and other authorities have begun framing climate change as a core occupational health issue rather than an environmental aside. Adapting practice requires several changes. Hazard anticipation must incorporate climate projections so that programs are built for the conditions of the coming decades, not the historical baseline. Heat must be managed as a year-round, multi-region hazard with formal programs, WBGT-based thresholds, and acclimatization schedules. Surveillance must broaden to capture chronic outcomes such as kidney disease and the compounding effects of simultaneous hazards. Standards bodies will need to revisit exposure limits in light of heat-chemical interactions and the realities of a warming climate. And the profession should engage with the policy process, including the OSHA heat rulemaking and international frameworks, because protecting workers from climate hazards is increasingly a matter of regulation as well as practice. Industrial hygiene is well positioned for this work; its anticipate-recognize-evaluate-control framework is exactly the discipline a changing climate demands.
Summary
Climate change is intensifying and spreading the hazards that industrial hygiene already manages. The ILO reports that over 70 percent of workers face climate-related health risks and that heat alone causes nearly 19,000 deaths a year, while the Lancet Countdown documents record labor-hour and income losses from heat. Hazard ranges are expanding in season and geography; chronic effects, such as heat-driven kidney disease, are emerging; and heat interacts with chemical exposures in ways that challenge existing exposure limits. The profession must anticipate these shifts, build year-round multi-hazard programs, broaden surveillance, and engage with the evolving regulatory landscape.
Helpful Resources
- ILO: Heat at Work: Implications for Safety and Health (2024)
- The Lancet Countdown on Health and Climate Change
- NIOSH: Climate Change and Occupational Safety and Health
- Related reading on this site: Wildfire Smoke and the Outdoor Workforce and Ultraviolet Radiation and Outdoor Workers.
Bibliography
Flouris, A. D., Dinas, P. C., Ioannou, L. G., Nybo, L., Havenith, G., Kenny, G. P., & Kjellstrom, T. (2018). Workers’ health and productivity under occupational heat strain: A systematic review and meta-analysis. The Lancet Planetary Health, 2(12), e521-e531. https://doi.org/10.1016/S2542-5196(18)30237-7
International Labour Organization. (2024). Heat at work: Implications for safety and health. A global review of the science, policy and practice. ILO.
Kiefer, M., Rodriguez-Guzman, J., Watson, J., van Wendel de Joode, B., Mergler, D., & da Silva, A. S. (2016). Worker health and safety and climate change in the Americas: Issues and research needs. Revista Panamericana de Salud Publica, 40(3), 192-197.
Kjellstrom, T., Briggs, D., Freyberg, C., Lemke, B., Otto, M., & Hyatt, O. (2016). Heat, human performance, and occupational health: A key issue for the assessment of global climate change impacts. Annual Review of Public Health, 37, 97-112. https://doi.org/10.1146/annurev-publhealth-032315-021740
Levi, M., Kjellstrom, T., & Baldasseroni, A. (2018). Impact of climate change on occupational health and productivity: A systematic literature review focusing on workplace heat. La Medicina del Lavoro, 109(3), 163-179. https://doi.org/10.23749/mdl.v109i3.6851
Romanello, M., Walawender, M., Hsu, S. C., Moskeland, A., Palmeiro-Silva, Y., Scamman, D., … Costello, A. (2024). The 2024 report of the Lancet Countdown on health and climate change: Facing record-breaking threats from delayed action. The Lancet, 404(10465), 1847-1896. https://doi.org/10.1016/S0140-6736(24)01822-1
Schulte, P. A., & Chun, H. (2009). Climate change and occupational safety and health: Establishing a preliminary framework. Journal of Occupational and Environmental Hygiene, 6(9), 542-554. https://doi.org/10.1080/15459620903066008
Schulte, P. A., Bhattacharya, A., Butler, C. R., Chun, H. K., Jacklitsch, B., Jacobs, T., Kiefer, M., Lincoln, J., Pendergrass, S., Shire, J., Watson, J., & Wagner, G. R. (2016). Advancing the framework for considering the effects of climate change on worker safety and health. Journal of Occupational and Environmental Hygiene, 13(11), 847-865. https://doi.org/10.1080/15459624.2016.1179388
Spector, J. T., Masuda, Y. J., Wolff, N. H., Calkins, M., & Seixas, N. (2019). Heat exposure and occupational injuries: Review of the literature and implications. Current Environmental Health Reports, 6(4), 286-296. https://doi.org/10.1007/s40572-019-00250-8
World Health Organization. (2023). Operational framework for building climate resilient and low carbon health systems. WHO.