Prevention and management of heat-related illness at mass gatherings: developing evidence-based communication messages

What this guideline says

GMJ summary

This 103-page WHO manual provides standardized, evidence-informed communication message templates to help prevent heat-related illnesses and injuries during major sporting events and other mass gatherings (religious events, cultural festivals). Based on a systematic review of 54 studies covering over 70 million attendees, the document translates technical guidance into actionable messages for five audience segments: attendees, officials, event staff (personnel, volunteers, contractors), health and first-aid services, and event organizers and leadership.

Messages are organized by event phase (pre-event, arrival and queuing, during event, departure, post-event) and aligned to four qualitative heat risk levels (normal/seasonal, increased risk, high risk, extreme risk) that can be mapped to local heat alert systems. Each message follows a standard structure: situation/trigger, required action, where/how to access support (safe water points, cooling areas, first aid), and when to seek urgent help. The framework emphasizes audience segmentation, temporal alignment, risk-tiered escalation, actionability linked to available services, plain language with translation-ready placeholders, and operational integration with early warning, surveillance, and event command structures.

The document includes minimum message sets by risk level, example deployment schedules for football match days, all-day festivals, and pilgrimages, channel-ready formatting for public address, screens, social media, SMS and signage, rapid approval workflows, escalation pathways, staff briefing scripts, monitoring logs, and post-event debrief templates. Five annexes provide message ID indexes, localization placeholder catalogues, copy-ready microcopy for rapid deployment, minimum practical templates, and a heat illness clinical quick-reference card for on-site first-aid staff.

Key points

For clinicians — doses and thresholds as stated in the guideline

1. Messages should only instruct actions that can be completed on-site: do not direct attendees to cooling areas, safe water points or first aid locations unless those services are available, accessible and operational at the time of messaging.
2. Communication intensity must align with heat risk level: normal/seasonal heat requires routine reminders; increased risk triggers earlier and more frequent messages; high risk demands frequent, directive messaging paired with operational changes (queue rerouting, additional safe water distribution); extreme risk requires very frequent, directive messaging with immediate protective action and event modification, suspension or evacuation if authorized.
3. Danger signs (confusion, collapse, seizures, not responding normally) require urgent emergency action: all messages classify these as medical emergencies requiring immediate first aid contact and rapid escalation according to local clinical protocols.
4. Staff and volunteer protection must follow occupational safety and health principles: shorter, more frequent rest breaks in cooled areas; scheduled hydration access; buddy systems for early symptom detection; rotation of staff assigned to high-exposure posts; and permission to stop work and seek medical support if unwell.
5. Pre-event planning checklist must confirm: local heat alert system alignment and thresholds, safe water point and cooling area locations inserted into message placeholders, first-aid locations and emergency contact numbers verified, priority languages identified, approval chain established, and post-event debrief scheduled within 24–72 hours.
6. Vulnerable groups (older adults, pregnant people, infants and young children, individuals with chronic medical conditions or taking specific medications, staff and volunteers with high heat exposure and metabolic heat production, non-acclimatized international visitors) require targeted messages and operational accommodations including easier access to safe water, cooling areas, rest, medical support, and welfare checks.
7. All translated messages must maintain actionability and clarity: use short sentences, active voice, plain language, one idea per sentence, avoid technical jargon, specify what to do/when/where, and ensure placeholders for [SAFE WATER POINT LOCATIONS], [COOLING AREA LOCATIONS], [FIRST AID LOCATIONS], [EMERGENCY NUMBER] and [OFFICIAL CHANNEL] are completed before deployment.
8. Heat illness cluster or surge (multiple heat-related presentations in a short period, in the same zone, queue, route or staff group) triggers immediate actions: increase cooling and safe water support at the affected location, review queue or crowd flow, issue targeted public message A13 or L6 if extreme risk, deploy additional staff or first-aid support, notify medical lead and operations centre, and reassess within a defined time interval.

Qualitative heat risk levels and recommended communication approach

Table extracted from the guideline

Source: World Health Organization, Prevention and management of heat-related illness at mass gatherings: developing evidence-based communication messages. Reproduced in summary form.

From the guideline

Verbatim

“Messages must be linked to functioning and accessible services. Harms occur when authorities promote actions such as seeking medical help that cannot be fulfilled because services are unresponsive or difficult to access.”

Editor’s perspective

Why this matters for Georgia and the region

Applicability

Georgia and the South Caucasus

Questions this guideline answers

Quick answers

Related on GMJ

Interconnected resources

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