Heat stress: the very real supply chain risk the fashion industry can no longer ignore

The temperature is 35 degrees celsius but feels like 40 degrees due to the humidity. The air is stifling, the garment dust making it hard to breathe. The old ceiling fan is creaking and full of dust too, barely cooling the air. Workers, used to not drinking too much to avoid frequent bathroom breaks, sip on water spiked with electrolytes but fainting, nose bleeds and heatstroke are common.

What sounds like a dystopian narrative is very much a reality in many garment factories right now. The heat wave that is currently gripping large parts of South and Southeast Asia is stalling work in garment and textile factories and making workers’ lives even harder.

A strong El Niño is currently pumping massive reservoirs of oceanic heat into the atmosphere, compounding the long-term effects of human-induced climate change to drive global temperatures to record-breaking levels: 38 degrees Celsius in India and between 32 to 34 degrees Celsius in Sri Lanka, Bangladesh and Pakistan.

If you have ever exited a plane that just landed and been exposed to the jet exhaust for a few seconds while doing so, imagine being in there for hours. Across Asia, this is what it feels like at the moment, with shifting tropical weather patterns suppressing rainfall and weakening trade winds, thus trapping stagnant, dry air over the continent and triggering prolonged, extreme heatwaves. Heat strain starts from a temperature of about 30 degrees Celsius; heat stress from 32 degrees Celsius.

What is heat stress?

A recent report by the NYU Stern Centre for Business and Human Rights, entitled “Too Hot to Ignore: Extreme Heat in Garment Supply Chains,” warns the garment and textile industry not to ignore heat stress. The World Health Organization identifies heat stress as the leading cause of weather-related deaths. It occurs when the body cannot cool itself sufficiently through sweating and thus experiences symptoms like headaches, heat exhaustion, heatstroke, kidney damage, reproductive health issues or aggravated underlying health conditions such as cardiovascular disease, diabetes, asthma and mental health disorders. Heat stress arises when individuals are exposed to excessive heat and humidity or undertake strenuous activity in hot environments - such as working in a garment factory for instance.

The report makes the point that climate-driven extreme heat can no longer be dismissed as a distant environmental concern; it has rapidly transformed into a core operational hazard. It underlines that rising ambient temperatures and soaring humidity levels across South and Southeast Asia are actively disrupting production ecosystems right now. It reframes extreme heat not merely as a peripheral sustainability metric, but as an immediate occupational safety and health crisis that fundamentally threatens the resilience of the global fashion supply chain.

To substantiate these findings, the research methodology employed by the NYU Stern team combined broad corporate tracking with deep, localised field analysis across India, the world’s sixth-largest garment exporter that is increasingly exposed to extreme heat.

The researchers conducted on-site investigations across ten apparel factories, collectively employing nearly 9,000 workers and spanning key industrial states, including Tamil Nadu, Haryana, Odisha, Maharashtra and Karnataka. They supply brands for the domestic (D-mart, V-mart, Joki) and international market (Jack & Jones, Levi’s, Marks & Spencer, Primark, S.Oliver, Target, Tom Tailor, Uniqlo and others).

The empirical fieldwork included interviews with approximately 80 workers onsite at nine of the factories and a further 40 interviews with them off-site to get a feel for heat exposure at living conditions. The report also tracked internal environmental variables and evaluated medical-room logs across multiple facilities to capture seasonal health spikes. Additionally, the researchers surveyed international footwear and apparel brands to evaluate the stark misalignment between corporate awareness and actual compliance oversight on the factory floor.

What physical and financial toll does heat stress take on workers?

The human toll of this escalating climate crisis falls square on the individuals operating the sewing lines. The report documents how indoor microclimates in manufacturing facilities often eclipse the dangerous conditions found outdoors, particularly within heavily industrialised zones. For instance, researchers recorded indoor temperatures reaching a staggering 43 to 45 degrees Celsius inside a fabric dyeing and processing unit, which actually exceeded the outside ambient heat by as much as 5 degrees Celsius. This oppressive indoor environment triggers severe physiological strain, with workers frequently reporting acute episodes of dizziness, chronic headaches, debilitating dehydration, fainting, skin rashes and severe kidney or urinary complications brought on by a lack of proper cooling and restricted rest periods.

Crucially, this physical suffering translates into a severe financial penalty for a workforce that is already heavily economically marginalised. The report reveals that heat-related healthcare costs and defensive expenditures—such as buying electrolytes or paying for medical treatment—drain between 500 and 1,000 rupees (5.30 to 10.60 US dollars) per month from a worker's pocket. Given that average monthly garment wages in these regions hover between 11,500 and 18,000 rupees (around 122 to 190 US dollars), these climate-induced out-of-pocket expenses represent a devastating chunk of household income. This financial erosion is compounded by immediate wage losses whenever workers are forced to take unpaid sick days due to heat exhaustion, illustrating how the poorest stakeholders in the fashion ecosystem absorb the direct economic shocks of global warming.

What does heat stress mean for factories and supply chains?

From a strictly commercial standpoint, the report outlines how extreme heat actively dismantles factory efficiency and compromises product standards during peak summer periods. Factory managers interviewed across nine operating facilities reported measurable productivity drops ranging from 3 to 10 percent during intense heatwaves, alongside an increase in worker absenteeism of roughly 2 to 5 percent. The physical toll on the workforce forces a natural slowing of the production pace, which directly jeopardises tight delivery schedules. Furthermore, extreme heat strains the machinery itself, causing frequent generator overloads and grid outages, such as an incident in April 2024 at a Faridabad knitwear facility that forced the complete closure of an entire production floor.

Beyond volume drops, the physical realities of a sweating workforce degrade the actual quality of the garments being manufactured. Excessive worker perspiration leads to fabric staining, while open windows and struggling ventilation systems allow external dust contamination to compromise clean assembly lines, resulting in a spike in stitching errors and structural defects.

“Extreme heat is now a predictable supply chain risk for apparel brands. Factories are losing output, quality is suffering and delivery timelines are at risk, not as a future scenario, but right now,” notes Lucy Siers, senior research scientist for global labour at the NYU Stern Centre. This reality forces manufacturers to choose between absorbing the costs of rejected merchandise or facing stiff penalties from brands for late shipments.

Whose responsibility is heat stress?

The broader narrative of the report exposes a profound governance failure within global fashion supply chains, characterised by a severe imbalance of power and responsibility. The researchers found that while 94.1 percent of international brands surveyed openly acknowledge that extreme heat poses a moderate to significant threat to their operations, their internal purchasing practices tell a completely different story. Only 35.3 percent of these brands mandate that their suppliers track internal heat or humidity levels, and absolutely zero brands collect this data on a continuous basis. This creates a convenient informational blind spot, allowing multi-national retailers to demand strict compliance with labour standards while remaining entirely ignorant of the literal sweatshop conditions their pricing structures perpetuate.

This operational disconnect means that the immense financial burden of climate adaptation is pushed entirely onto the suppliers. Tight purchasing margins, volatile order volumes and brutally short lead times imposed by brands systematically starve factory owners of the capital needed to invest in necessary structural overhauls.

Michael Posner, Director of the NYU Stern Centre, addresses this systemic failure directly, arguing that brands sourcing from heat-exposed regions have a clear commercial and ethical mandate to remain and assist: “The answer is not to walk away from these sourcing regions and leave workers and suppliers behind. It is to invest in making them more resilient by requiring heat monitoring, setting clear safety standards, building flexibility into purchasing practices when heat disrupts production and sharing the cost of cooling and ventilation upgrades."

Key recommendations

To redress these structural vulnerabilities, the report offers a series of targeted, non-negotiable recommendations for all key actors across the textile value chain, starting with global buyers. First, brands and retailers must formally categorise extreme heat as a core occupational safety hazard and integrate continuous indoor temperature monitoring into their standard supplier audits.

They are urged to move towards a shared-responsibility financial model, co-funding engineering upgrades like passive cooling infrastructure and high-volume fan installations, while building explicit timeline flexibility into production schedules during heatwaves. A successful precedent is highlighted at Epic Group’s Bhubaneswar facility, where a joint financial partnership with the International Finance Corporation utilised automated systems to maintain a stable indoor environment of 28 degrees Celsius.

Simultaneously, the report calls for aggressive intervention from domestic governments and international industry regulators to codify these protections. National regulatory bodies must establish legally binding indoor workplace temperature thresholds and enforceable work-rest schedules that trigger automatically when specific heat indices are breached. Governments should also extend existing national heat action plans to formally encompass indoor industrial environments and classify heat stress as a compensable occupational illness within state-sponsored social protection frameworks.

Finally, suppliers must implement immediate local safeguards, such as ensuring worker wages are fully protected during heat-induced output drops, and establishing democratised factory committees to give workers a direct voice in identifying and mitigating heat risks on the floor.