Hanoi tops world pollution charts: How can psychology help us change?

Hanoi tops world pollution charts: How can psychology help us change?

As Hanoi claims the unwanted title of “world's most polluted city”, RMIT psychology experts explain how a combination of individual and collective behaviour changes can alleviate the situation.

Recently, Hanoi has been crowned as the world’s most polluted city after placing high in global pollution rankings for years. Not just confined to the capital city, air pollution is a nationwide problem with IQAir's 2023 World Air Quality Report naming Vietnam as the second most polluted country in ASEAN. 

Air pollution stems from many sources—industry, construction, production, waste burning, and traffic—and many wonder how individual actions can make a difference. Two psychologists at RMIT University Vietnam, Ms Vu Bich Phuong and Dr Katrina Phillips, believe that change is possible if we can strategically translate psychological principles into practice.

“We don’t all need to change; small actions can create big change once a tipping point is reached. Research shows that potentially when as little as 3.5% of the community commits to new behaviours, meaningful change follows,” Dr Phillips suggests. 

Hanoi has recently topped the world’s pollution charts. (Photo: Unsplash) Hanoi has recently topped the world’s pollution charts. (Photo: Unsplash)

Why do we stick with harmful habits?

One habit ripe for change in Vietnam is the heavy reliance on personal vehicles, says Ms Phuong.  

Personal vehicles offer immediate perks such as speed, convenience, no waiting time, and humans often prioritise short-term rewards over long-term benefits. Such instant rewards bring satisfaction to our brains, and this gratification is the starting point of forming bad habits: once it feels good, we will continue to do it, to the point when such behaviour is performed automatically without much conscious awareness.  

Thus, “we optimise for immediate outcomes, even if delayed rewards are better for us”, Dr Phillips explains. 

This mental shortcut is driven by how our brains form habits. Ms Phuong adds, “Habits help us save brain energy by automating decisions. In contrast, conscious thinking and planning, such as choosing bus over motorbike, happens at the prefrontal cortex, a more evolved brain area for humans but is also more energy consuming.” 

Over time when a behaviour repeats, the brain learns to form a shortcut, shifting decision-making from the energy-intensive prefrontal cortex to the dorsal striatum, the brain’s habit centre. Breaking this loop is difficult but possible.  

Changing habits requires more than willpower

Research has shown that changing a habituated behaviour requires more than a single approach; it demands a comprehensive, multi-level strategy that considers the context in which behaviour occurs. This includes interventions at the individual, community, and national levels, Ms Phuong suggests.    

At the individual level, classic behavioural theories from psychology can be used to influence habits. Although brain shortcuts are easily formed, they are not immutable—we can “unlearn” behaviours through the same mechanisms.  

(L-R) Ms Vu Bich Phuong - Associate Lecturer of Psychology, and Dr Katrina Phillips – Senior Lecturer of Psychology, RMIT University Vietnam (L-R) Ms Vu Bich Phuong - Associate Lecturer of Psychology, and Dr Katrina Phillips – Senior Lecturer of Psychology, RMIT University Vietnam

Providing rewards for desirable actions, such as incentives for using public transportation, can strengthen new habits. Conversely, punishments or deterrents, like personal vehicle charges or higher parking fees, can discourage undesirable behaviours. Consistency and repetition are key to maintaining motivation and forming new, good habits.   

But individual motivation alone is not enough—it must be structurally supported. Alternative and more sustainable options (improved public transport, for example) need to be more available to make it attractive.  

Social norms and modelling also play a role. Portraying public transport as modern and responsible lifestyles can reshape collective attitudes.

Research continuously shows that awareness alone does not drive action. “We’re past the education phase,” Ms Phuong asserts. “We need structured, evidence-based interventions to overcome inertia now.” 

Policy matters

At the national level, regulation, infrastructure, and clear communication are key. The successful launch of the first metro lines in Hanoi and Ho Chi Minh City shows that Vietnamese people are ready and willing to embrace positive change when it is well-executed. “Now is the time to build on that momentum,” Ms Phuong believes. 

The first metro line in Ho Chi Minh City was launched in December 2024. (Photo: Pexels) The first metro line in Ho Chi Minh City was launched in December 2024. (Photo: Pexels)

For those who are not ready for a complete change to public transportation, the government's support for alternative energy vehicles will provide more options to ease the transition toward sustainable transportation. 

Nonetheless, strategic infrastructure planning must be combined with clear, transparent communication to outline the benefits, potential disruptions, and long-term impacts of transportation reforms. People will commit fully to their decisions if the benefits are clear to them.

These recommendations are based on the Behaviour Change Wheel (Michie et al., 2011)—a comprehensive theoretical framework that integrates individual, social, and policy-driven interventions into a unified model for behaviour change. This evidence-based framework has been adopted by the World Health Organization (WHO) and UNICEF as a foundation for developing large-scale health and environmental behaviour change initiatives.

These behavioural principles in psychology are not new. Historically, they have been useful in various contexts and thus gained substantial scientific evidence. However, pro-environmental behaviour change is especially challenging as it involves many stakeholders. "Therefore, it is crucial to be more consistent, coordinated, and radical to achieve lasting, impactful change," said Ms Phuong.

Chart showing Behaviour Change Wheel (Source: Michie et al., 2011) Behaviour Change Wheel (Source: Michie et al., 2011)

While both RMIT lecturers are excited to see the current movement to public transport, they emphasise inclusivity as behavioural change can disproportionately affect certain populations, including low-income individuals, people with disabilities, and those living in rural areas. Inclusive planning and equitable access to resources are non-negotiable to foster widespread, sustainable change.

As a scientific discipline, psychology offers valuable insights to understand group behaviour and foster change.

"In the future, I hope to see greater engagement from psychologists in addressing society’s most pressing challenges and more opportunities for their expertise to shape policy-making processes aimed at behavioural change," Ms Phuong concludes.

Thumbnail image: Deemerwha studio – stock.adobe.com

10 January 2025
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