Mitigating Heat Stress Among Rickshaw Drivers in Bangladesh

How Does Heat Stress Affect Telomere Length? A Pilot Randomized Controlled Trial in Urban Bangladesh

The goal of the experimental study is to understand the impact of heat stress on core temperature and telomere length. Investigators will recruit rickshaw drivers who use manual power to push their rickshaws and randomly assign half of them to receive battery-powered rickshaws to use for four months. Investigators will assess how this change impacts their core body temperature while they work, the length of their telomeres (caps on the end of DNA that are associated with aging), and kidney function.

Study Overview

• Status: Not yet recruiting
• Conditions: Telomere Length, Mean Leukocyte; Core Temperature; Kidney Function Issue
• Intervention / Treatment: Device: Battery-powered rickshaw

Detailed Description

Personal exposure to heat may be elevated above ambient temperatures if an individual is very active (which generates metabolic heat) or wears clothing that prevents cooling. Age can influence the consequences of heat stress. Older adults are at elevated risk of adverse impacts from heat stress due to their reduced ability to dissipate heat. Heat stress is particularly high among outdoor workers. South Asia has millions of bicycle rickshaw drivers, who use their muscles or battery power to pull hundreds of pounds of passengers and goods on modified bicycles. When manual rickshaw drivers rest to cool off, they reduce their already meager income. Heat stress not only threatens their livelihoods and thereby their right to an adequate standard of living but also their right to work, given that they have few employable skills other than manual labor. South Asia faces the greatest current and predicted loss in disability-adjusted life years due to heat stress, and heat stress is particularly strong in informal settlements. As such, the investigators plan to conduct this study in Dhaka, Bangladesh. The overall hypothesis is that driving a battery-powered rickshaw will reduce heat strain. The investigators will evaluate the impact of driving a battery-powered rickshaw on core temperature (primary outcome), telomere length, kidney function, heart rate, heart rate variability, sleep quality, self-reported thermal comfort, mental health, wellness, and fatigue (secondary outcomes).

• Study Type: Interventional
• Enrollment (Estimated): 300
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Laura Kwong, PhD; Phone Number: 16504609593; Email: lakwong@berkeley.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Reports driving a manual rickshaw at least five days per week for at least 8 hours per day for the past 12 months

Exclusion Criteria:

• Reports driving a battery-powered rickshaw in the past 12 months
• Has hypertension, as measured by our study staff
• Has diabetes, as measured by our staff
• Reports diagnosis with cardiovascular disease / chronic cardiac condition
• Reports diagnosis with respiratory disease / chronic respiratory condition

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Manual rickshaw; Rickshaw drivers will use manually powered rickshaws
Experimental: Battery-powered rickshaw; Rickshaw drivers will use battery-powered rickshaws	Device: Battery-powered rickshaw; A battery-powered rickshaw is a rickshaw where the wheels are turned by a small electric motors powered by a battery.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Core temperature	Minutes per day that core temperature is >40C, where fewer minutes per day is better	0 (pre-intervention) and 2, 4, 6, 8, 10, 12, 14, 16 weeks post-intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Relative Leucocyte Telomere Length	Change in Relative Leucocyte Telomere Length measured by PCR, where a smaller reduction in length is better	0 (pre-intervention) and 16 weeks post-intervention
Kidney function	kidney function, as measured by a the neutrophil gelatinase-associated lipocalin (NGAL) value in urine samples, where a lower score is better	0 (pre-intervention) and 2, 4, 6, 8, 10, 12, 14, 16 weeks post-intervention
Heart rate	resting heart rate (bpm), where a lower heart rate is better	0 (pre-intervention) and 2, 4, 6, 8, 10, 12, 14, 16 weeks post-intervention
Heart rate variability	resting heart rate (bpm) variability, where higher variability is better	0 (pre-intervention) and 2, 4, 6, 8, 10, 12, 14, 16 weeks post-intervention
Sleep quality	Self-reported sleep quality and number of minutes in REM, as recorded by a fitness watch, where more minutes in REM is better	0 (pre-intervention) and 2, 4, 6, 8, 10, 12, 14, 16 weeks post-intervention

Collaborators and Investigators

• Sponsor: University of California, Berkeley
• Collaborators: International Centre for Diarrhoeal Disease Research, Bangladesh; North South University
• Investigators: Principal Investigator: Laura Kwong, PhD, University of California, Berkeley

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2025
• Primary Completion (Estimated): October 31, 2025
• Study Completion (Estimated): December 31, 2025

Study Registration Dates

• First Submitted: April 25, 2025
• First Submitted That Met QC Criteria: April 25, 2025
• First Posted (Actual): May 4, 2025

Study Record Updates

• Last Update Posted (Actual): May 21, 2025
• Last Update Submitted That Met QC Criteria: May 15, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: Bangladesh; sleep quality; heart rate variability; heart rate; heat stress; heat strain; rickshaw
• Additional Relevant MeSH Terms: Wounds and Injuries; Heat Stress Disorders
• Other Study ID Numbers: 2023-05-16316

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: We will post de-identified participant data on our OSF repository (https://osf.io/sd285/)
• IPD Sharing Time Frame: We expect that data and code will become available by 1 Jan 2027
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No