Living Barometers: co-constructing climate-health knowledge with outdoor workers

Co-construction is not a decorative gesture. It is a political and methodological commitment to shifting who holds authority over knowledge and whose realities shape policy. This piece describes what that commitment looked like in practice when we worked alongside informal outdoor workers on climate-related health risks across four major Vietnamese cities – Hanoi, Da Nang, Ho Chi Minh City and Can Tho – and what this approach surfaced that
a standard design would have missed.

Workers as living barometers

Vietnam is one of the most climate- vulnerable countries in the world, with climate impacts already costing an estimated 3.2% of GDP in 2020 and projected to reach 12 to 14.5% of GDP annually by 2050 (World Bank, 2022). Approximately 70% of Vietnam’s labour force is employed informally (ILOSTAT, 2023), and informal outdoor workers, including street vendors, construction labourers, porters and motorbike taxi drivers, are among the first to experience climate-related disruptions, yet among the least protected (Weston-Stanley et al, 2026). They experience climate risk not as environmental data but as a daily working condition, a health risk and a determinant of income.

Across all four cities, the research documented a consistent phenomenon we term ‘cảm xạ thời tiết’, or embodied weather sensing: a systematic capacity workers develop through decades of direct exposure, reading rain from shifts in wind direction, smelling approaching floods before water rises, sensing temperature changes through the skin. This is real-time climate monitoring with a precision no instrument yet replicates. Workers also register shifts in weather predictability over time. The phrase ‘Before, rain had its seasons; now you just don’t know how to prepare’ appeared consistently across cities and occupational groups.1 One Hanoi worker captured the bodily precision of this knowledge plainly: ‘I can feel it right in my chest when the humidity’s too high. It’s not something a machine has to tell me.’

Workers described a collective pattern they call ‘say nắng mãn tính’, chronic heat illness, a condition absent from
any clinical classification because the formal health system has never had to name something it does not treat (Vu, 2025). This is what Miranda Fricker (2007) calls epistemic injustice: harm done to a person specifically as a knowing subject. The World Health Organization’s Special Report on Social Participation in Health and Climate (WHO, 2025) makes the same point at a governance scale: excluding embodied knowledge from adaptation planning costs both equity and accuracy.

What co-construction actually meant

The principles behind co-construction are not new. They have been central to critical development research for decades (Cornwall, 2008). And yet the challenge persists: participatory methods remain widely promoted but rarely embedded. In our research, this meant a sustained, four-phase practice rather than a methodological label.

The study involved 400 informal outdoor workers across two survey rounds, 43 in-depth interviews, and 141 extended field visits lasting between four and eight hours across Hanoi, Da Nang, Ho Chi Minh City and Can Tho between April and August 2024. Workers shaped research questions, tested and revised survey instruments, co-analysed data in group sessions, and reviewed outputs before publication (Vu, 2025), consistent with Cornwall’s (2008) distinction between participation as consultation and participation as genuine power-sharing.

One instance illustrates how co- construction improved the research itself. A street vendor observed that childcare responsibilities during heatwaves were absent from our draft survey. She was right. We restructured several items. The instrument improved, and so did our understanding of what we were studying.

Fieldwork followed the logic of extended accompaniment rather than scheduled interviewing. Researchers spent full working days alongside participants: on foot, on motorbikes and at rest stops. The field diary became a methodological tool: a space to register what had not been asked, what had been assumed and what still needed following up.

Three things the method surfaced

The knowledge-action gap is structural, not behavioural. The research found that chronic illness, low income, insecure housing and limited access to health infrastructure are significantly associated with increased susceptibility to climate-related health risks and reduced ability to cope (Weston-Stanley et al, 2026). Workers knew what protective action looked like, but faced structural barriers that made it unachievable. The economic logic is captured precisely in one Da Nang worker’s account of why stopping during heat stress is not a real option: ‘If I stop working when I feel dizzy, who will pay for dinner?’ What policy frameworks call behavioural choices are in reality constrained decisions, calculated trade-offs between health and survival (Whitmee et al, 2015).

Adaptation is collective, not individual. Peer networks function as informal early warning systems, exchanging microclimatic intelligence, providing mutual support and collectively assessing risk. Workers in Ho Chi Minh City described slowing down as a group when one member felt unwell: ‘We take turns helping each other. It’s not just one person’s problem.’ These are not coping strategies: they are critical, systematically undervalued components of adaptive capacity that never appear in formal assessments.

Resilience has a ceiling. Workers were not simply enduring; they were exhausted by having to endure. Mental health conditions and lack of digital access further constrain perceived coping ability, reflecting not only differential exposure but deeper structural constraints on the capabilities required to avoid harm and adapt (Weston-Stanley et al, 2026). Peer solidarity fills a structural gap that formal protection should occupy, and workers know it.

From co-construction to co-design

Workers co-developed the survey instrument, which we came to call the ‘living barometer’ tool, reflecting their capacity to sense, record and interpret climate-health data through their bodies and experience. They also collaborated in building the Intelligent Climate Alert Network, a geographic information systems-enabled mobile app delivering localised weather-health alerts, identifying critical features, testing prototypes and shaping functionality. Many became regular users and peer promoters, an outcome that illustrates how knowledge co-production
yields tools that continue to serve the communities involved (Vu, 2025; Palmeiro-Silva et al, 2026).

Workers also participated as co- interpreters alongside government and civil society actors in a series of deliberative roundtables, covered by local media in a country where this kind of horizontal policy dialogue is rare. This reframing, from workers as research subjects to workers as knowledge authorities, is precisely what the Belém Health Action Plan calls for through its emphasis on democratic dialogue and bottom-up approaches to climate- health governance (WHO, 2025).

Practical lessons

• Build in more time than the timeline allows. Our most important methodological insights came from the eighth hour of a field visit, not the first.
• Treat discordant data as a signal. Not all workers wanted to participate in network-building activities, a finding in tension with the study’s participatory optimism. We kept it in because honesty about limits is part of the method.
• Name epistemic injustice as a policy problem. No existing data mechanism in Vietnam currently captures what workers’ bodies are registering as input for climate planning. That is a systematic gap in the governance architecture, not a gap in the knowledge itself.
• Informal workers do not need to be empowered. They are already adapting, analysing and organising. What they need is recognition, redistribution and policy designed with them rather than for them.
• Further information: https://climate-health-vietnam.org 

Contact: anh.vu@natcen.ac.uk 

References

Nguyen, D.L., and Vu, N.A. (forthcoming) Sach Xanh 2026/Green Book 2: climate change and informal outdoor workers in urban Vietnam. SocialLife Research Institute.

Farmer, P. (2004) Pathologies of power: health, human rights and the new war on the poor (Vol. 4). University of California Press.