Subway systems are uncomfortably hot — and worsening

Analysis of more than 85,000 social posts reveals rising thermal discomfort

Northwestern University

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For millions of commuters, the workday doesn’t just begin with a train ride. It also begins with a blast of heat.

In one of the largest studies ever conducted on thermal comfort in metro systems, Northwestern University scientists found that subway riders consistently report feeling uncomfortably hot while underground. 

Rather than relying on traditional surveys — which are expensive and capture only brief snapshots of conditions in time and place — the team turned to real-world feedback. Searching for comments about thermal discomfort underground, the scientists scraped social posts and online reviews published between 2008 and 2024. Then, they analyzed more than 85,000 crowdsourced comments from across Boston, London and New York.

The findings show a clear pattern: As above-ground temperatures rise, below-ground thermal complaints increase. The scientists hope their work could help transit agencies anticipate extreme heat, implement targeted mitigation strategies and adapt underground infrastructure to an ever-warming climate.

The study will be published on Tuesday (March 10) in the journal Nature Cities.

“No one wants to feel uncomfortable,” said Northwestern’s Giorgia Chinazzo, who led the study. “But while discomfort might seem like a minor inconvenience, extreme heat also represents a serious threat to public health. Extreme heat causes more deaths per year than all other natural hazards combined. Having information about when and where people feel uncomfortable could help transit agencies and policymakers make targeted interventions, such as increasing the number of operating fans during specific times of day.”

An expert on how buildings influence people’s health and wellbeing, Chinazzo is an assistant professor of civil and environmental engineering at Northwestern’s McCormick School of Engineering, where she directs the Architectural Engineering and Design Program. Chinazzo authored the study with Alessandro Rotta Loria, the Louis Berger Associate Professor of Civil and Environmental Engineering at McCormick.

It’s getting hot in here

Most people have heard of urban heat islands — a phenomenon in which a metropolitan area is significantly warmer than surrounding rural areas. But many people might not realize that urban heat doesn’t stop at the sidewalk. It seeps into soil, tunnels and underground transit systems — where it lingers. 

Unlike above-ground spaces, underground environments retain heat because soil and rocks can act as thermal insulators. In some areas, below-ground temperatures can even exceed surface records. Subsurface temperatures in the London Underground, for example, have reached 47 degrees Celsius (116 degrees Fahrenheit), surpassing London’s highest recorded air temperature.

Chinazzo and Rotta Loria wondered how this heat affects people’s daily lives. In a 2023 study, Rotta Loria quantified the rising temperatures in subterranean transportation systems, parking garages and basement facilities. But long-term data on how commuters actually experience underground temperatures are scarce.

Untapped data

To bridge that gap, the team turned to crowdsourcing. Commuters vent their frustrations online every day, including exasperation about sweltering subway stations. Yet no prior studies have used crowdsourced data to examine thermal discomfort in underground metro systems. Focusing on subway systems in London, Boston and New York, the team analyzed more than 85,000 posts from X and Google Reviews.

“We focused on these three cities because their transit systems are the oldest and biggest,” Rotta Loria said. “London has the oldest metro system in the world. In the U.S., Boston has the oldest system, and New York has the largest one. In principle, this technique could be applied to any place on Earth, but this was our starting point.”

After collecting posts, the team used natural language processing to extract comments with keywords like “hot,” “warm,” “uncomfortable,” “roasting,” “scorching” and “boiling,” while omitting those keywords when unrelated to thermal (dis)comfort. For example, the technique filtered out comments about “hot dogs,” “warm smiles” and “uncomfortable crowds.” In the end, the team confidently identified more than 22,000 thermal complaints, posted across a 16-year period. Those posts represented various times of day and all seasons.

When comparing the complaints to recorded temperatures, Chinazzo and Rotta Loria found that for each increase in 1 degree Celsius above 10 degrees Celsius, complaints increased by 10% in Boston, 12% in New York and 27% in London. Complaints peaked during summer months — especially July — and spiked during major heatwave years such as 2018 and 2019.

Although complaints spiked in summer months, commuters still expressed some discomfort in colder weather. As a possible justification, commuters may often be dressed warmly, prepared for freezing outdoor temperatures. But, after venturing underground, they may feel overdressed and uncomfortable in the warmer subterranean conditions.

“Even in winter, people may complain because they are wearing heavy clothing,” Rotta Loria said. “It’s another facet of the same problem.”

Energy-efficient interventions

Chinazzo and Rotta Loria also discovered that timing matters. In London, complaints tend to spike in the late afternoon. In Boston and New York, complaints peaked at noon and again at 9 p.m. In general, complaints decreased on the weekends. These findings suggest that social factors, not just temperature, shape how people experience heat.

“Thermal conditions are not necessarily better on the weekends,” Chinazzo said. “But the metro might be less packed, and people might be dressed more comfortably. State of mind also matters. For example, a tourist on vacation might be less inclined to complain compared to someone headed to work.”

By analyzing complaint trends — both in real time and retrospectively — could help inform targeted, energy-efficient heat-mitigation strategies. For example, running fans more throughout the whole day every day might help people feel more comfortable. But it also might waste energy when more fans are not needed.

“Depending on the metro system under consideration, it may not make sense to cool down the underground environment all day,” Rotta Loria said. “But we could enhance cooling during specific times when we know people are uncomfortable. That means spending less energy and less money.”

The consequences of extreme heat

Unfortunately, underground heat is not just uncomfortable. It’s also potentially consequential. In addition to affecting public health, extreme heat can deform train rails, accelerate the aging of mechanical components, affect groundwater quality, disturb civil infrastructure foundations and disrupt underground ecosystems.

Chinazzo and Rotta Loria emphasize the urgent need for expanded public datasets on underground environmental conditions, which remain sparse worldwide. Improved monitoring and transparency could help engineers, transit agencies, urban planners and policymakers prepare for a hotter future.

“Essentially, underground environments are hot, and it’s because of us,” Rotta Loria said. “When trains brake, they release heat. Most lighting systems release heat. Humans release heat. Then heat also comes from the surface. The primary driver is us. The heat underground is because of us. And it’s up to us to solve it.”

The study, “Thermal discomfort in urban underground metro systems,” was supported by the National Science Foundation (award number 2046586).

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Journal

Nature Cities

DOI

10.1038/s44284-026-00404-4 

Article Title

Thermal discomfort in urban underground metro systems

Article Publication Date

10-Mar-2026

 

Increased risk of bullying in open-plan offices

Workplace Bullying in the Open: the Risks Associated with Working in an Open Office

Linköping University

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image: 

Michael Rosander, professor at the Division of Psychology at Linköping University, Sweden.

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Credit: Anna Nilsen

Open-plan offices entail a clearly increased risk of workplace bullying compared with employees having their own office or sharing with just a few colleagues. This is shown in research from Linköping University, Sweden. 

“Increased bullying is a tangible negative consequence of how you choose to organise the workplace. It’s important to highlight this, as it hasn’t previously been examined,” says Michael Rosander, professor at the Division of Psychology at Linköping University.

Open-plan offices, where many employees share the same space, have become increasingly common. Employers often justify this development as a way to use premises more efficiently and to encourage creative interactions between employees. However, research has shown that open-plan offices do not promote health, job satisfaction or productivity.  

Until now, it has been unclear whether open-plan offices also affect the risk of bullying and employees’ motivation to look for another job. Through surveys of more than 3,300 randomly selected individuals in employment in Sweden, Michael Rosander has now provided an answer. The results are published in the journal Occupational Health Science. 

Thirty per cent of those with some form of office-based work reported that they worked in a traditional open-plan office with no access to private space. Thirteen per cent worked in so-called activity-based offices, where employees spend part of their time in an open-plan environment but also have access to designated rooms for tasks requiring peace and quiet. The remainder had their own office or shared one with only a few colleagues.

For traditional open-plan offices, the survey responses showed a clearly increased risk of bullying compared with those who had their own office or shared an office with only a few colleagues. The difference remained regardless of factors such as personality traits and the extent of remote working. This suggests that the problems are indeed caused by the work environment in the office.  

The researchers’ explanation is that in traditional open-plan offices it is easier to notice colleagues’ shortcomings and become irritated by them. If someone gets frustrated and takes it upon themselves to “do something about” a colleague’s behaviour, and there are no clear guidelines for handling such situations, there is a risk that it may escalate into bullying. Those who are subjected to bullying lack access to a private space for retreat. 

Activity-based open-plan offices, by contrast, showed no increased risk of bullying, likely due to the availability of private spaces. However, in both types of open-plan office, employees were more likely to consider changing jobs. One possible explanation is that activity-based offices also involve more distractions, according to Michael Rosander.

For employers who have introduced, or are planning to introduce, open-plan offices, there are some lessons to be learned. One is to be prepared to deal with irritation and conflicts before they escalate. Another is the importance of providing rooms where employees can work undisturbed. Placing individuals with similar needs and tasks near one another may also reduce the risk of disruption.

“Traditional open-plan offices are in themselves negative for the individual, for productivity, and make people more likely to leave their job. Social interaction also suffers. So it's worth considering how to handle it,” says Michael Rosander.

The research was conducted in collaboration with Morten Birkeland Nielsen at the University of Bergen and was funded by Forte (the Swedish Research Council for Health, Working Life and Welfare).

Michael Rosander, professor at the Division of Psychology at Linköping University, Sweden.

Credit

Anna Nilsen

Journal

Occupational Health Science

DOI

10.1007/s41542-025-00246-x 

Method of Research

Survey

Subject of Research

People

Article Title

Workplace Bullying in the Open: the Risks Associated with Working in an Open Office

Frequent scrolling affects perceptions of the work environment

University of Gothenburg

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Individuals who perceive that colleagues prefer to scroll on their mobile phones during breaks rather than socialise rate their psychosocial work environment as poorer than others do. This is shown in a doctoral thesis from the University of Gothenburg.

Research has shown that mobile phone scrolling can impair relationships. For example, many people feel that the quality of conversations deteriorates when phones are used at the same time. However, few studies have examined how relationships between co-workers are affected. In his doctoral thesis, psychologist Per Martinsson has therefore investigated what happens when mobile phones displace social interaction during breaks. The studies were based on the concept of phubbing, derived from “phone snubbing”, which refers to prioritising one’s phone over people who are physically present.

Mobile phones often perceived as a barrier

The results of 25 interviews with electricians and healthcare professionals show that mobile phones are often perceived as a social barrier that leads to less socialising and conversation during breaks. Phones are also used as a way of withdrawing from social interaction, which may stem from a need for recovery.

The results of two survey studies involving a total of approximately 1,700 working adults show that those who perceive more phubbing from their co-workers also report a poorer psychosocial work environment in terms of emotional and practical support, trust, sense of community, and engagement in their work and organisation.

“It is interesting that one’s own mobile phone use does not appear to be associated with these factors, but what others do may play a role,” says Per Martinsson.

The findings from the two quantitative sub-studies, one among electricians and one based on a broad sample of working adults in Sweden, both indicate a negative association. However, no evidence was found that mobile phone use drove a deterioration in the work environment over a one-year period, and further research is needed to clarify the causal relationships.

Norms differ between groups

Mobile phone scrolling at work also appears, to some extent, to be a generational issue. Younger employees use their phones more during breaks and are also more likely to consider it acceptable for others to use their phones. Several interview participants emphasised that mobile phone use during breaks is not solely negative; phones are sometimes incorporated into social interaction, for example when searching for information or looking at pictures and videos together.

“Since norms and expectations differ between groups, an important skill is being able to read the situation, understanding how and when it is socially acceptable to use one’s phone, and in which situations it may be perceived as excluding others,” says Per Martinsson.

Reflection and dialogue can make a difference in the workplace

“These findings shouldn’t be taken to mean that more rules are needed or that staff must put their phones away during breaks. Rather, I hope my findings will encourage reflection and discussion about this issue in the workplace. We can talk about how we want things to be and how we can create a good work environment together,” says Per Martinsson.

FACTS

• The thesis will be defended on 13 March 2026.
• Title of the thesis: Coworker phubbing: Smartphone use during work breaks and the psychosocial work environment
• Link to the thesis: https://hdl.handle.net/2077/90500
• About the studies: The thesis comprises one interview study and two survey studies. Twenty-five individual interviews were conducted with electricians and healthcare professionals. Thematic analysis was used to identify recurring themes in the interviews. One survey study targeted electricians and was completed by approximately 800 respondents. The second survey was distributed to a representative sample of the working population in Sweden via the SOM Institute and was completed by just under 900 respond

Online meetings come with pros and cons – managers should understand all of them

University of Eastern Finland

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Video meetings have become a staple in the workplace. A recent study among senior IT industry managers shows that video meetings have a dual impact on remote leadership. Although Teams, Zoom and other tools for video meetings have become embedded in day-to-day organisational practices, their role in leadership has not been thoroughly examined from the perspective of technological opportunities and constraints – until now.

Conducted at the University of Eastern Finland, the study found that video plays a dual role in leadership. On the one hand, video meetings serve as an informative tool when management wishes to share information, for example, in staff briefings or in pre-recorded video messages. On the other hand, video meetings serve as an interactive tool when managers wish to engage in discussions with teams and individual employees.

Video is considered a flexible and efficient means of sharing information. However, interactive use of video technology also has its challenges: the study identified five key tensions that influence the daily work of managers.

The first tension relates to flexibility and inflexibility. While video meetings streamline time management, yet they also create additional strain and result in fully-booked calendars. Flexibility makes it easier to work from different locations and time zones, but an overcrowded schedule causes stress.

The second tension pertains to social connection and social distance. Video makes it possible to maintain a sense of community, but it also limits spontaneous interaction and the expression of emotions. People don’t necessarily experience genuine social connection – even when cameras are turned on.

The third tension identified in the study involves participation and passivity. While technology provides tools for fostering active engagement, managers also face challenges in encouraging participation when people prefer not to turn on their cameras, multitask during video meetings or remain silent behind their screens.

The fourth tension relates to the sharing of formal information and the lack of informal knowledge. Formal information moves efficiently via video connections, but tacit knowledge and subtle cues are easily lost.

The fifth tension highlights equality and inequality. Video meetings increase equality between locations, but at the same time accentuate differences in how employees participate and work.

The study introduces a new theoretical framework that describes the dual role of video technology in remote leadership. The findings emphasise that successful remote leadership is not only about a leader's communication skills but also about the ability to find a balance between what technology enables and what it limits.

”Our study offers concrete recommendations for managers who wish to support their employees' well-being, interaction and ability to work in digital environments,” says Professor Jonna Koponen of the University of Eastern Finland.

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Journal

Information Technology and People

DOI

10.1108/ITP-09-2024-1157 

Article Title

Dual edge: exploring technological affordances and constraints of video technology in e-leadership

Article Publication Date

3-Mar-2026