Sweating it Out: Vietnam’s Workers in Extreme Heat

SLO – Lacking social support, outdoor laborers are paying the price of rising heat with their health and their pocket.

A woman working at a salt flat. PHOTO: Hong Son under Creative Commons license via Pexels.

HO CHI MINH CITY, VIET NAM – Construction worker Nguyễn Minh Tú (a pseudonym) remembers collapsing at about 10am on a summer day last year, gasping for air.

At 45 and physically strong, she was not fazed by heavy shoveling, but feared the heat steaming from the concrete on the ground.

Source: Mapbox

“The heat was brutal. I almost passed out,” she recalled.

A few minutes later, Tú collected herself and stood up, but she has not checked her health since. In the days leading up to the incident, her heart had pounded faster while her vision dimmed – signs of heat exhaustion.

Millions of outdoor workers like Tú have been facing serious health risks as heatwaves reach unprecedented levels in Viet Nam. Informal laborers, lacking health care access, bear the burdens of this extreme weather.

Tú is trapped in a dilemma. She bought her own health insurance, as informal workers are not entitled to health insurance or free checkups, but cannot afford the time off work. A hospital visit means losing one day’s pay, and possibly her job, to someone younger and stronger, she said.

Heat stress in many regions across Viet Nam have already been severe and are set to worsen in the coming decades, a report released in April by the French Development Agency (AFD) warned.

The report showed that from 1995 to 2014, nearly all regions in Viet Nam experienced days when the Wet-Bulb Globe Temperature (WBGT) – a key measure that factors in temperature, humidity, radiation and wind to prevent heat stroke – exceeded 32°C.

At this level, workers should limit their activities to 15 minutes per hour to keep their core body temperature lower than 38°C, a dangerous threshold. In some regions, WBGT even surpassed 37°C, when work should be halted entirely.

Annual number of days when daily maximum WBGT (wet-bulb globe temperature) exceeds 32°C in three emissions scenarios & three future periods (NF-near future, MF-mid future, FF-far future). GRAPHIC: Nguyen-Le et al. (AFD, 2025). Additional annotations by Mekong Eye.

In the south-central coast and southern regions, more than one third of the year has had a WBGT level above 32°C.

A wet-bulb temperature of 32°C can mean 41°C at 50% humidity, or 37°C at 70% humidity – a common baseline in many parts of Viet Nam. Since the body primarily cools through sweat evaporation, high humidity severely limits heat loss.

That is why heat waves are much more lethal in the tropics.

The report projected rising annual maximum WBGT levels under all emissions scenarios – by up to 3°C in the far future under a high-emissions pathway. The number of days exceeding the 32°C threshold will also increase nationwide, with the sharpest rises in the south-central coast and southern regions, including the densely populated, agriculturally vital Mekong Delta.

The report warned that climate-induced heat stress in Hanoi and Ho Chi Minh City would be intensified by the Urban Heat Island (UHI) effect, when hard surfaces, residential and industrial activity and air pollution drive urban temperatures higher than those of rural areas.

How human body heats up and cools down. GRAPHIC: Buzan and Huber (2020)

The higher the humidity, the more difficult it is for the human body to cool. The border between the yellow and red areas represents the threshold at which core body temperature rises. GRAPHIC: W. Larry Kenney under Creative Commons license via The Conversation

Day-to-day threats

Ninh, a ride-hailing driver speaking under a pseudonym, likened Hanoi’s streets to a frying pan as temperatures soared past 40°C in June.

On the hottest days, he started work before dawn to avoid the worst of the heat, then retreated to his rented room by midday, unable to bear the sweltering, smoggy streets.

His protective suit included two layers of masks, three shirts, a head scarf, sunglasses and shoes – but they barely helped. Some evenings he returned home drenched in sweat, his heart pounding, his hands red from sun exposure.

“The app offers a little extra bonus during heatwaves, but it’s not worth it,” he said. “If I collapse on the road, who’s going to take care of my wife and kids back home?”

Vũ Ngọc Anh, Research Director at the UK’s National Centre for Social Research, said nearly 60% of informal outdoor workers must work during peak midday hours (10am-2pm) when temperatures are the most dangerous.

Traffic jam under harsh sunlight in Ho Chi Minh City. PHOTO: Daniel Stewart via Unsplash under Creative Commons license.

Anh’s research showed that half of these workers suffered from chronic conditions like depression, joint or immune diseases. More than 90% have experienced skin issues, sunstroke or heat shock.

While Viet Nam lacks comprehensive official data on the health effects of heat on outdoor workers, a 2023 study found a clear link between rising temperatures and increased emergency visits to hospitals in Hànội.

Scattered incidents reported by state media are beginning to highlight the toll. On June 1, 2025, a regional medical center in Phú Thọ province admitted seven patients with heatstroke or heat exhaustion – one in a critical condition requiring intubation.

Most had worked outdoors for long hours before developing symptoms like severe fatigue, muscle cramps and limb convulsions. Doctors warned that prolonged exposure to extreme heat can cause excessive sweating, leading to dehydration and electrolyte imbalance.

Without timely treatment, this may result in hypovolemic shock, heart failure or even death. High body temperatures can also disrupt vital systems, including cardiovascular, respiratory and nervous functions.

In Ho Chi Minh City, Thống Nhất Hospital reported a 20% surge in patient numbers at the start of last year’s heatwave, according to Tuổi Trẻ. In March 2024, the hospital treated 2,200 to 2,500 patients daily, with cardiovascular and respiratory conditions dominating the caseload.

Many were heat-related, including infections and heat-exacerbated heart and ear, nose and throat problems.

At the city’s Dermatology & Venereology Hospital, heat-related skin conditions also spiked after the 2024 Lunar New Year. About 100 patients per day sought treatment for sunburn, heat rashes and photosensitive dermatitis.

Health problems by extreme weather experienced at work reported by 400 informal outdoor laborers between May and July 2024. SOURCE: Vũ Ngọc Anh

Trapped in precarity

Faced with life-threatening risks, many outdoor workers feel social support is limited, Anh said.

“They feel isolated, and the precariousness of their lives is very iconic,” Anh told reporters at the First Global Heat Health Information Network (GHHIN) Southeast Asia Heat Health Forum in Singapore earlier this year.

Her research showed that only 27% of informal outdoor workers sought professional care when sick. Strikingly, nearly 60% used their own money to buy voluntary medical insurance, but few used it when ill.

Many workers normalize and downplay heat-related health issues, viewing them as just part of their job, so they should not complain or seek help, Anh said. This, Anh explained, is a coping mechanism to deal with chronic stress and anxiety.

“This is a quite concerning issue, and we should take it into account when designing policies,” she emphasized.

Vũ Ngọc Anh speaks at the Southeast Asia Heat Health Forum. PHOTO: GHHIN Southeast Asia Heat Health Forum

Tú, for instance, has come to accept her heat exhaustion and slower recovery as a natural sign of aging.

“I buy insurance just in case, but hopefully I’ll never need to use it – that would mean I’m still healthy,” she said, smiling.

Yet her reluctance to seek care runs deeper. As a migrant, she struggles with navigating city streets, dealing with complex hospital procedures and long wait times at overcrowded public hospitals.

Claiming health insurance benefits also requires multiple layers of paperwork and referrals between hospitals, which further discourages her.

What weighs most heavily, however, is her fear of losing work. Contractors eye older workers like her with suspicion, doubting their stamina. Without family support and formal qualifications, she had no choice but to power through the discomfort.

Anh’s research confirmed larger burdens are placed on women and older workers. Women faced more challenges juggling childcare and housework, while younger workers adapted better and suffered less income loss than their older counterparts, Anh told reporters at the forum.

A vendor protects herself against the sun with a conical hat, a face mask and a jacket. PHOTO: Francois Le Nguyen via Unsplash under Creative Commons license

Real protection

Tú has her own version of a heat-protective suit: a conical hat, a hand-me-down denim jacket and two cloth scarves wrapped tightly around her head and lower face.

Yet these makeshift solutions fall far short of offering real protection.

Government agencies, employers, civil society and local communities all have vital roles to play – from prevention through awareness campaigns and cooling stations, to response mechanisms like health insurance coverage and paid sick leave during heatwaves.

Viet Nam’s current policies focus on natural disaster reduction and infectious disease prevention, but neglect heat-related health risks, said Trần Nữ Quy Linh, a senior researcher at the University of Queensland at the Southeast Asia Heat Health Forum.

Surveillance systems primarily track infectious diseases, with limited attention to heat-exacerbated illnesses like cardiovascular or respiratory conditions.

In addition, prevention of heat illnesses is under-prioritized and coordination among sectors – health, meteorology, disaster management – is insufficient.

Viet Nam also lacks a robust heat-health warning system that provides localized, timely and actionable alerts. The absence of health and weather data further limits the accuracy and coverage of heat advisories.

The country has only just started taking steps to mitigate the impacts of extreme heat on its labor force. The Department of Climate Change under the Ministry of Natural Resources and Environment is working with international partners to develop a comprehensive National Cooling Action Plan (NCAP).

A technical consultation for the initiative was held on June 24, 2025.

The Prime Minister’s Decision No. 496/QĐ-TTg, issued in June 2024, also laid out a national plan to phase out ozone-depleting substances and greenhouse gases. It included urban and rural cooling initiatives and a roadmap for implementing sustainable, climate-resilient cooling measures nationwide.

Earlier, in mid-2023, the Department of Environmental Health Management (now the Department of Disease Control under the Ministry of Health) issued public guidelines on heatwave healthcare. These aimed to equip communities and workers with basic knowledge for preventing and responding to heat-related illness.

Yet major policy gaps remain – especially when it comes to protecting the health rights of Viet Nam’s vast informal workforce. A report by the Social Life Research Institute published in June flagged a critical shortfall in access to regular health checkups for this high-risk group.

While formal-sector workers are entitled to at least one free annual health screening under Article 21 of the 2015 Law on Occupational Safety and Hygiene, informal outdoor workers – despite facing more severe climate-related risks – are excluded from such routine care.

Construction workers resting in the shade. PHOTO: Dương Phước Tiến under Creative Commons license via Pexels

As the afternoon heat finally started to ease, Tú’s face was still flushed, her forehead beaded with sweat.

For workers like her, extreme heat is not an abstract climate statistic – it’s the pounding heart at noon, the blistered hands, the spinning head and the quiet decision to keep going because stopping is simply not an option.

Unless cities, employers and policymakers act faster, that burden will only grow heavier and deadlier with each passing summer.

The names of localities, cities and provinces in this article reflect changes in Viet Nam’s administrative reform, which took effect on July 1, 2025.

Kiều Mai – Mekong Eye