Impacts of Climate Change on the Health of Outdoor Workers in Urban Asia

About

This systematic literature review of the health impacts of climate change on urban outdoor workers in Asia synthesises the findings of 18 studies. It examines climate-related health risks, vulnerabilities, coping strategies, and adaptation measures employed by outdoor workers. It identifies critical gaps in understanding the direct and indirect health effects of climate-related stressors including extreme heat, air pollution, and other weather-related hazards. It explores the vulnerabilities of outdoor workers and notes areas for future research and policy intervention.

This review provides a comprehensive synthesis of existing research, focusing on the vulnerabilities and adaptation strategies of outdoor workers exposed to climate-related stressors such as extreme heat, air pollution, and other weather-related hazards. With the increasing frequency and severity of extreme climate events, such as heatwaves and floods, outdoor workers, particularly migrants and those in informal sectors, face heightened health risks. These risks are compounded by limited access to healthcare, social marginality, and inadequate protective measures at work.

The paper is the first output from the Wellcome Trust-funded project "The Health Impacts of Climate Change on Precarious Outdoor Workers in Urban Megacities in Vietnam." It sets the stage for further research to address the identified gaps and to enhance policy responses. By doing so, it aims to improve the health outcomes of outdoor workers in urban Asia and inform future climate resilience strategies.

Key findings

• Predominance of quantitative methods: the majority of studies used quantitative methods, with nine exclusively quantitative and eight employing mixed methods, though the qualitative component was minimal.
• Lack of participatory approaches: none of the studies actively engaged target groups in co-producing knowledge or used participatory research methods.
• Dominance of heat-related health risks: heat-related health issues, such as heat cramps, heatstroke, and cardiovascular problems, are the most extensively documented, especially in high-risk sectors like construction and street vending.
• Limited focus on mental health impacts: while the physical health effects of climate change, particularly heat exposure, are well-documented, mental and cognitive health impacts have received significantly less attention.
• Air pollution as a major health exacerbator: air pollutants like PM2.5, nitrogen oxides, and sulphur dioxide aggravate respiratory and cardiovascular diseases, particularly for low-income outdoor workers in high-traffic and industrial areas.
• Vulnerability of informal sector workers: outdoor workers in the informal sector, especially those with pre-existing health conditions, face heightened risks due to exposure to multiple climate-related stressors and limited access to healthcare.
• Disproportionate vulnerability of specific groups: the elderly, women, and those with pre-existing health conditions are at greater risk of heat-related illnesses, highlighting the intersection of climate vulnerability and social inequities.
• Under-reporting of health impacts: many outdoor workers avoid reporting climate-related health symptoms due to fear of job loss, lack of awareness, and inadequate reporting mechanisms, leading to delayed treatment.
• Ineffective coping strategies: common coping strategies, such as increased hydration and shifting work hours, are insufficient in protecting workers from extreme weather, compounded by inadequate urban infrastructure.
• Inadequate policy frameworks: existing policies fail to adequately protect outdoor workers from climate-related health risks, with a need for localised measures, such as heat-health warning systems, air quality monitoring, and occupational safety standards.

Methodology

The methodology for this systematic evidence review followed a rigorous, five-stage process. Conducted between February and June 2024, the review focused on English-language, peer-reviewed publications, specifically targeting outdoor workers in urban settings. The review concentrated on urban Asia.

The process began with the development and testing of search strings related to climate change, climate variability, health, and health outcomes. In the second stage, the team screened papers based on content, publication type, date, geography, and language, using criteria tailored for the review. The third stage involved piloting search terms across four databases—Google Scholar, Scopus, PubMed, and Web of Science—to assess the strength of search strings and inclusion criteria.

Following the piloting, the search terms were refined, and comprehensive searches were conducted on Scopus, Web of Science, and PubMed. The results were then screened to identify relevant studies. In total, 734 papers were initially identified, and after removing duplicates, 535 papers remained for title and abstract screening. This was further narrowed down using inclusion and exclusion criteria, resulting in 26 papers for full manuscript review.

Finally, after screening the full text of the 26 papers, 18 papers met the inclusion criteria for systematic evidence review. These 18 papers were extracted and assessed in a tabular format, summarising themes, research questions, methods, health impacts, extreme weather impacts, coping strategies, and policy recommendations.