After climbing three flights of stairs of a building in Hong Kong’s bustling Mong Kok district, where sacks of concrete sit by half-patched walls, we find an open metal gate and a wooden door adorned with red and gold decorations welcoming the Lunar New Year. It is about 8 p.m. and the air is stale, thick with humidity from a bathroom shared by 12 and dust from the building’s ongoing renovation. At the far end of the corridor, the only window is cracked open, facing bamboo scaffolding and the low hum of voices from the street below. But barely any wind or cool air comes through, with the temperatures outside running high for February, a month that used to bring cold weather.

Inside a windowless wooden compartment, which barely fits a single mattress and its occupant, is Leung Chung Leung, wearing a red t-shirt, checked shorts, and rubber slippers. The 74-year-old has lived in this rental bed for nearly a decade. After losing his job as a cook due to an accident that left him with a permanent leg injury and then getting evicted from a subdivided flat, Leung was pushed into the cheapest available accommodation in the city: a cage home, also known as a coffin home, where he pays HK$2,500 (around US$320) per month, in addition to HK$300 every three months for water and electricity.

When he thinks about the summer months, Leung’s raspy voice grows animated: “It’s hard, it gets very hot,” he told The Diplomat.

In the evenings, Leung relies on an old fan perched on a small table beside his bed. Some nights, he also needs to leave his bedroom door open to catch whatever cool air drifts in from the shared air conditioning unit in the corridor, which operates only between 6 p.m. and 7 a.m.

When the temperatures soar, he said that he spends more time in a nearby public park than inside his tiny bedroom, where he keeps a small television, a plastic kettle, Tupperware containers, and three packs of cigarettes scattered on a shelf above his bed. Sometimes he needs to take three showers a day. “There isn’t much else I can do,” Leung said.

Elderly people like Leung are bearing the brunt of rising temperatures in Hong Kong. The Diplomat visited 11 units occupied by elderly residents. Most lived in cage homes – squeezed into 15 to 18 square feet – where ventilation and other resources to keep themselves cool were limited. After record-high temperatures gripped the city this winter, experts and advocacy groups call for “real action” to tackle extreme heat, as its most vulnerable residents face a silent life-threatening crisis.

For generations, Hong Kongers have mostly welcomed the Lunar New Year wrapped in warm layers. But last month, some even reached for the air conditioning. The city registered its hottest Lunar New Year’s Eve since records began in 1884, with the thermometer hitting 27.9 degrees Celsius. According to authorities, Hong Kong has experienced the warmest winter on record over the past three months.

While some perceive soaring temperatures as just an inconvenience, others are facing real danger. Most deaths during heatwaves “occur in people over 60 with heart disease, lung disease, diabetes, or on certain medications,” said David Bishai, director of The University of Hong Kong School of Public Health. “People who live alone and who don’t have or don’t use AC are vulnerable too,” Bishai noted, adding that pregnant mothers in the third trimester are at greater risk of having premature births.

A recent paper, which is under review, showed that heatwaves had become the 10th leading cause of death in Hong Kong, claiming as many lives as diabetes.

Bishai said the city’s growing elderly population needed further attention. “It is really the older group that is falling through the cracks and not benefiting from a territory-wide heat health action plan,” he noted.

Hong Kong has become one of the world’s most rapidly ageing societies, with more than 20 percent of its population now 65 or older. According to the latest census, it is expected that one in three residents will be aged 65 or above by 2036.

As of the third quarter of last year, government data showed that 247,700 older residents lived alone – nearly 75,000 more than in 2020, which corresponded to a 43 percent increase in just five years.

Eva Yeung, senior manager of Community Resilience Service from the Hong Kong Red Cross, said that many elderly residents do not realize how rising temperatures affect their health. “Because the heat comes gradually, they may dehydrate slowly while living in environments that are too crowded or too small or too stuffy,” she said. “When they realize it, it may be already too late to alert a health practitioner.”

The Nighttime Problem

In Hong Kong, which has consistently ranked as one of the least affordable places in the world to own a home or even rent a flat, adaptation to rising temperatures is not equal. While many people live in modern high-rises with advanced filtration and cooling systems, thousands face sweltering temperatures that make life inside their flats unbearable. Some of those facing greater challenges find themselves in subdivided flats that have been carved up into smaller units, each with its own walls and door. Others are trapped in cage homes, communal rooms partitioned by metal mesh or wooden boards, where residents sleep in stacked, coffin-like bunks with barely enough room to sit up.

Coco Au, 71, a retiree living off disability assistance subsidies, moved to a cage home in Mong Kok, which has been described as the world’s densest place to live, about a decade ago after her husband passed away. Au’s cubicle does not even allow for the door to fully open. Wedged between the wall and her single bed, covered with colorful cushions and teddy bears, two small tables hold a rice cooker, an ashtray made out of a can, scissors, a pen, and a paper cup of tea.

In the flat, there are 13 other units like this one. When the temperatures are mild, Au said that residents often open the flat’s only window, which is just a few meters away from her bedroom. But even that is far from ideal. “Sometimes we see Mickey Mouse,” she said, caught between amusement and disgust. “There are rats and cockroaches… It cannot be avoided.”

Although Au said she does not have space for a fan, she has an old air-conditioning unit inside her bedroom. But she avoids turning it on for fear of high electricity bills. Au pays HK$2,500 monthly rent plus about HK$300 for bills when temperatures rise. “Sometimes, I have to open the AC. Otherwise, I cannot stand the heat. But I try not to,” she said.

Au’s room, where a paper calendar, clothes, and dozens of red plastic bags dangle above her narrow bed, is so cramped that a doctor has told her to go on walks as much as possible, she said, while showing how impossible it is to stretch her slim legs inside her cubicle.

Au said that not just the lack of space, but also the high temperatures have taken a toll on her declining health. “There are nights when I cannot fall asleep,” she said. “It’s very hot and it’s getting worse every summer.”

A survey released last year by two local groups, CarbonCare InnoLab and the Kwai Chung Subdivided Units Kai Fong Association, found that more than 70 percent of respondents had experienced fatigue from extreme heat, with many developing symptoms such as headaches, dizziness, and heart palpitations. About 90 percent of those surveyed also said the heat had impacted their mental health, leaving them stressed and irritable.

Residents reported that summer nights in Hong Kong’s subdivided flats could feel as hot as 44 degrees Celsius in July.

Researchers say that Hong Kong’s unique vertical architecture, high density, and growing elderly population present a lethal combination during heatwaves.

“Heat definitely can kill more people in the high-density areas,” said Ren Chao, professor in the Faculty of Architecture at the University of Hong Kong. She noted that the problem of subtropical climate cities like Hong Kong is not so much the daytime but the nights. While both hot days and nights have soared in recent years, the number of hot nights has grown at a faster pace.

Research conducted by the Chinese University of Hong Kong’s Institute of Future Cities and the University of Hong Kong in 2020 concluded that five consecutive “hot nights” – 28 degrees Celsius or above – and “very hot days” increase the mortality risk by 6.66 percent and 3.99 percent, respectively.

Ren added that extreme heat is not the only problem, but also sudden temperature fluctuations, which are becoming more frequent.

Although the climate design expert estimated that about 95 percent of buildings in Hong Kong are equipped with air conditioners, she said that’s hardly the only answer to high temperatures, noting that they contribute to generating further heat outdoors.

Sze Lai Shan, deputy director of the local non-profit Society for Community Organization, agreed: “It’s becoming hotter and even when the landlord installs an air-conditioning, it may not be sufficient.”

She estimated that about 30 percent of the residents in cage homes are elderly.

In recent years, Sze has watched the heat take a quiet toll, with more residents facing health conditions triggered or worsened by temperatures that seem to climb a little higher each season. “It happens not just to the elderly, but also to some middle-aged people. Some develop fevers, coughs, and other issues, which force them to see a doctor,” she said.

Testing Alternative Solutions

Chow Ngan Ying, 73, has to deal with high temperatures both at home and at work. “I am so tired that I don’t have problems sleeping even when it’s very hot,” she said, with a laugh. In her cage home in Mong Kok, Chow said she has everything she needs, pointing to scarves and floral tops hanging at the foot of her bed, and then to small plastic boxes filled with coins and a portable black fan stacked against the left wall. Two analogue clocks and a plastic lion toy sit on a small table. The bed has no mattress, just three thin blankets.

Chow, a woman with short hair and a wide smile, juggles two jobs: she spends eight hours cleaning a shopping mall during the day, then puts in another six-and-a-half hours as a street cleaner. “The mall job is easier because I can get AC there,” she said.

Outdoor workers in Hong Kong – including street cleaners, sanitation staff, and construction workers – are increasingly vulnerable to extreme temperatures, with previous surveys showing that many had experienced symptoms of heat exhaustion or heatstroke. In 2023, the city’s Labor Department introduced a three-tier Heat Stress at Work Warning, along with specific guidelines for employers, but these recommendations remain non-binding.

Getting ready for another night shift, Chow dons a bright green t-shirt with reflective strips over a black long-sleeve top and a mask across her face. “I just prefer not to spend much time at home,” she said, before slipping a metal padlock through her cubicle latch.

While advocates have called for stronger protections for outdoor workers, they say much more also needs to be done inside the homes of the most vulnerable residents, where stifling heat prevents many from resting.

Hong Kong passed a landmark bill last year regulating the city’s subdivided flats, setting minimum standards that landlords must meet by 2030. Under the new regime, which started being rolled out this month, units must have at least 86 square feet with ceiling heights of 2.3 meters, a dedicated toilet, and at least one openable window.

A security guard of a building in Mong Kok said that many subdivided flat residents had left in recent months due to rising costs, echoing earlier concerns raised by lawmakers about landlords passing the cost of renovations, required to meet the new standards, on to tenants. A volunteer, who requested not to be named and has for years visited residents living in subdivided units, said she worried that some might have gone “underground” and to even worse accommodation that does not meet government regulations.

Xia Baolong, head of the Hong Kong and Macau Affairs Office, has previously urged the city to “bid farewell to subdivided flats and cage homes” by 2049. But Hong Kong’s newly passed legislation stopped short of addressing the city’s infamous cage homes. Rather than being folded into the new Basic Housing Units regime, they will continue to be regulated separately.

Yeung, of the Hong Kong Red Cross, estimates that there are over 220,000 people living in subdivided units and another 200,000 people residing in squatter areas in Hong Kong, where houses are often built with tin sheets that trap the heat inside small homes.

She said that the Red Cross has deployed a team of volunteers to help declutter and clean the homes of older residents who cannot manage on their own, and distributed dehumidifiers, fans, and other appliances to replace older models that generate excessive heat.

But her team has also begun searching for longer-term and innovative answers. Last year, working alongside the Hong Kong University of Science and Technology, the Red Cross installed sensors in roughly 30 households in squatter areas. The data that came back was striking: indoor temperatures in some of those homes were running higher than outside.

Yeung, who leads the international non-profit’s heatwave adaptation programs, said that they identified eight households where a cooling coat, recently developed by researchers at the Hong Kong Polytechnic University, had been applied. Compared with conventional coatings, experts said the new formulation can reduce the temperature by up to 25 degrees Celsius when used in concrete rooftops. By limiting how much heat buildings absorb from the sun, researchers said that it can also help ease the excess warmth that leaves cities hotter than surrounding areas – a phenomenon known as the “urban heat island effect,” common in neighborhoods packed with concrete and asphalt.

Yeung said that the Red Cross was planning to identify another batch of households that can benefit from this innovative solution later this year.

Charity Oxfam Hong Kong is running a similar project to support grassroots residents in subdivided units, where the electricity meters are often shared, which leads to higher costs when using air conditioning. “Some residents do not have enough space to install an air conditioner, while others are worried about the financial burden of switching it on,” said Terry Leung, director of Oxfam’s Hong Kong, Macau, Taiwan Program. To address this, “we started working with a technology start-up to provide special coatings and window films that reflect solar radiation and absorb heat, helping to lower indoor temperatures.”

Advocates have called on the government to help tenants shoulder the rising cost of electricity bills and embed cooling measures into landlord-required standards.

In recent years, local authorities have worked with power companies to provide subsidies for low-income households and subdivided flat tenants.

When the city’s Observatory issues a “very hot weather” warning, the government has also opened 19 community halls and centers across all 18 districts as temporary heat shelters, while reserving space in eight additional facilities for daytime relief. Between 10:30 p.m. and 8 a.m., shelters have provided bedding for those who need to escape high temperatures.

But after analyzing the 19 heat shelters, expert Ren said researchers concluded that the number was insufficient in most high-risk areas. Yeung, of the Red Cross, agreed that more cooling centers are needed near the places where the most vulnerable communities reside.

A survey conducted by Greenpeace Hong Kong and homelessness charity ImpactHK last year showed that 65 percent of respondents had not used heat shelters because of their inconvenient locations, and a third were not even aware of the existence of such facilities.

Most users rated their experience negatively, with privacy receiving the lowest rating on a five-point scale at 2.34. The heat shelters were rated 2.77 for opening hours and staff attitude.

“It’s Not Just About the Temperature”

At a wider level, climate design expert Ren said local authorities should introduce additional measures to lower temperatures in the city, including more green spaces downtown and ventilation corridors to avoid heat-trapping concentrations of concrete.

A spokesperson for the Environment and Ecology Bureau said that “the government attaches great importance to combating the challenges posed by extreme heat. A range of measures are underway to enhance the city’s resilience through urban planning, building design, energy efficiency, and greening efforts.”

She said that the Hong Kong Planning Standards and Guidelines are being reviewed to incorporate wider climate adaptation and mitigation strategies. In addition, about 1.48 million trees and 30.2 million shrubs and herbaceous plants have been planted across the city over the past five years.

The spokeswoman said authorities have also explored “the use of innovative materials, technologies, and design approaches that can effectively alleviate extreme heat and improve urban comfort.” By mid-year, she revealed that a local start-up is set to begin production at EcoPark, an industrial hub in Tuen Mun, converting locally sourced recyclable waste into the core components of cooling devices that require no electricity.

However, experts fear that Hong Kong might be lacking a comprehensive strategy to mitigate the heat crisis. From Dhaka to Melbourne, cities around the world have in recent years appointed chief heat officers, tasked with raising awareness, coordinating emergency responses, and building long-term defenses against the dangers of soaring temperatures.

“In Hong Kong, our government is very experienced with typhoon preparation, event management, resilience, and recovery,” Ren said. But “so far, there is no real action” when it comes to addressing extreme heat.

While “the physical damage is visible after every typhoon or heavy rainfall, heatwaves are a silent killer,” she said. Because health data usually takes about two years to be available, Ren explained, “we cannot see the immediate health impact.”

The 2026-27 budget speech, delivered last month, did not mention specific climate adaptation measures to tackle extreme heat. The green initiatives included in the speech were mostly focused on waste reduction, recycling plans, and support for green industries.

“We are actively implementing the Hong Kong Climate Action Plan 2050, as we strive to reduce our carbon emissions by half from the 2005 levels before 2035 and achieve carbon neutrality before 2050,” Financial Secretary Paul Chan Mo-po said.

In a statement reacting to the budget, the international NGO Greenpeace slammed the lack of “people-centered climate initiatives” and “zero support” for vulnerable groups, including the homeless, residents living in subdivided flats, and outdoor workers.

Friends of the Earth Hong Kong, a grassroots environmental organization, has called on the government to “mandate heat adaptation plans for public housing estates and schools.”

Although Hong Kong has tried to respond to rising temperatures through shelters, improved heat-warning systems, infrastructure updates, and long-term climate policies, advocates and specialists argue that more coordinated adaptation measures are required as climate change worsens.

University professor Ren said that even though research has established a correlation between soaring temperatures and health risks, it is not easy to draft a policy or implement design that effectively mitigates the problem.

“We need interdisciplinary collaborations to understand the changing climate at the district level and also understand this kind of high-density urban context and its population,” she noted. “It’s not just about temperature. We need to put it into context, like the temperature plus humidity, temperature plus air pollution, and also considering the social demographic disparity and ageing population issues,” Ren said.

In her opinion, one of the greatest future challenges for Hong Kong is how to become a “healthy high-density city.”

When it comes to tackling climate change, while the “government should have a clear policy strategy and allocate enough resources to deal with it,” Ren noted that the private sector, residents, and non-profits also need to do their fair share.

Health economist Bishai said that municipal heat health action plans could help citizens, government agencies, and non-profits to know what they should do when heatwaves come. “Paris was able to lower its heatwave mortality by 90 percent by having and using a plan like this,” he said. In the French capital, “there is a team of thousands of volunteers who have a list of people who are vulnerable because of housing and health conditions. During heatwaves, they call and check on them. Some NGOs are doing this in Hong Kong, but it is not systematic.”

Yeung agreed that more collaboration is essential. Describing extreme heat as a “core issue,” she urged stakeholders with “power and resources” to unite around it. Addressing the problem requires combining “data, science, and technology” to protect the most vulnerable communities, she said.

Leung, the 74-year-old living in a cage home in Mong Kok, knows that the record-breaking Lunar New Year’s warmth is likely to be a prelude to a sweltering summer. When asked if he was concerned, the man with scarred legs contracted his face into a grimace, then laughed loudly. “Of course, I am,” he said, sitting on his bed, hands resting on his swollen knees, while a blue and white checked shirt hung behind him. “I cannot bear the heat.”

Raquel Carvalho is a recipient of a climate adaptation grant by the Brazilian Association of Investigative Journalism and the think tank Instituto Talanoa. This article was reported with the support of the grant and is being co-published with the Hong Kong Free Press.