The Department of Social and Preventive Medicine, Faculty of Medicine, Universiti Malaya, highlights the growing public health concern surrounding the current heatwave affecting Malaysia, as forecasted by MetMalaysia through September. Public Health Medicine Specialists Prof. Victor Hoe and Prof. Sanjay Rampal offer expert insights into the pressing risks associated with extreme heat and humidity, particularly focusing on wet-bulb temperature and its health impacts.

Understanding the Heat-Health Link

Prof. Victor Hoe underscores that high heat and humidity compromise the body’s natural cooling mechanism—sweat evaporation—leading to serious health risks such as heat exhaustion and heatstroke. The risk is magnified for vulnerable populations, including older adults, young children, individuals with chronic illnesses, and those living in suboptimal housing conditions.

Workers exposed to outdoor or poorly ventilated environments, including construction, factory, and informal sector workers, face elevated danger due to sustained exposure without adequate cooling or hydration. Prof. Hoe emphasises the need for coordinated public health strategies, including heat-adapted work schedules, better ventilation, and access to shaded rest areas.

What is Wet-Bulb Globe Temperature (WBGT)?

The Wet-Bulb Globe Temperature (WBGT) is a composite index that measures the effect of temperature, humidity, wind speed, sun angle, and cloud cover (solar radiation) on the human body. Unlike standard air temperature (dry-bulb temperature), WBGT better reflects how environmental heat stress affects health, particularly in outdoor or occupational settings. When WBGT values are high, the risk of heat-related illness increases significantly—even at air temperatures below traditional thresholds.

Policy and Technological Adaptation

Both professors advocate for the adaptive use of existing technologies such as the MySejahtera app, proposing enhancements to deliver real-time heat alerts, symptom checkers, and occupational health prompts. They also call for health system readiness, which includes equipping clinics and hospitals to manage heat-related cases and establishing cooling centres in high-risk areas.

Prof. Sanjay Rampal draws attention to the limitations of current public heat alerts, which rely solely on dry-bulb temperature. He recommends adopting a heat index or WBGT approach that includes humidity and solar radiation to guide health advisories more accurately. Such action is crucial, especially in Malaysia’s consistently humid equatorial climate.

Practical Public Guidance

The recommendations are clear:

Stay hydrated throughout the day.
Avoid outdoor activity during peak heat hours (12–3 p.m.).
Wear loose, breathable clothing and use fans or air-conditioning when possible.
Regularly check on at-risk individuals, including the elderly and chronically ill.
Never leave children or elderly individuals in parked vehicles.

For employers, adopting flexible work hours, improving workplace ventilation, and ensuring access to hydration and rest are essential.

A Shared Responsibility

Malaysia’s escalating heat events signal broader climate challenges that demand proactive, inclusive public health responses. The commentary from Prof. Hoe and Prof. Rampal calls for cross-sector collaboration between health, meteorology, urban planning, and technology sectors to reduce preventable heat-related illness and fatalities.

The article is a summary of responses by Prof Dr Victor Hoe and Prof Dr Sanjay Rampal for the article Malaysia at risk of deadly humidity threat published in the Star Newspaper on 9 June 2025.

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