Introduction: When Planning Is Not an Option, It's a Necessity
Organizing health coverage for a public event is much more than positioning an ambulance at the entrance. Every event has unique characteristics: the number of people present, the type of audience, the venue, environmental conditions, and the level of risk associated with the event itself. Without a structured method, health planning becomes an approximate exercise that can put participants' lives at risk.
Over the years, mass gathering medicine (the discipline that studies health management of large gatherings) has developed specific tools to address this challenge. Among these, the Maurer algorithm is one of the most widespread and practical: a risk assessment system that allows physicians, nurses, first responders, and organizers to objectively estimate how many and what health resources to deploy before an event.
What Is the Maurer Algorithm
The Maurer algorithm is a risk assessment system for public events and mass gatherings. It is based on a score calculated from a set of variables related to both the event and the expected audience.
The result, a number, expresses the danger potential of the event. That number corresponds to a risk threshold (very low, low, moderate, high, very high) and, consequently, a minimum set of health resources to be deployed: emergency ambulances, transport ambulances, foot patrol operators, and medicalized units.
In other words, the algorithm transforms a subjective assessment ("this event seems risky to me") into a structured and documentable estimate. It is a communication tool as well as a planning tool: it provides a common language among organizers, emergency services, and health authorities.
Origin and International Diffusion
The algorithm takes its name from Klaus Maurer, a German engineer with experience in the safety and emergency management sector in the context of large events. The method was developed from operational experience in the field of civil protection and emergency services for large events.
The Maurer algorithm has established itself as a consolidated operational reference in Germany and Austria, where it is frequently used in authorization procedures for public events. In those contexts, it is adopted by municipal authorities as part of the authorization process for large events.
The tool's diffusion has extended beyond German-speaking borders. In subsequent years, adapted versions or versions inspired by the original model have been integrated into national and regional protocols in various European countries, including Italy, where it has been adopted as a reference for health risk assessment in public events.
How It Works: The Logic of the Score
The algorithm's mechanism is intuitive: each variable is assigned numerical values based on the weight of the risk it represents. The values are combined according to a mathematical formula that generates a final score, the so-called risk index of the event.
The algorithm combines the various assigned values that identify risk inclinations, providing as a result the overall risk score; based on the result obtained, it is possible to determine the risk level and the relative score.
The formula is not linear: some variables multiply with each other, amplifying the combined effect of interacting factors. This reflects operational reality: an outdoor event with 10,000 excited people is not simply riskier than one with 5,000, but can be disproportionately so if other simultaneous risk factors are added.
The final score falls within a threshold scale:
- Very low / low risk → obligation of preventive notification to the territorial emergency service
- Moderate / high risk → advance notification, transmission of the health plan, compliance with requirements
- Very high risk → notification well in advance, validation of the detailed health plan by the emergency service
Variables Considered
The algorithm considers two main categories of variables: those related to event characteristics and those related to the audience.
Event-related variables:
- Maximum venue capacity (A): the value increases with the size of the site and doubles for indoor spaces, where risks related to density, air circulation, and evacuation are amplified.
- Number of expected visitors (B): usually estimated in blocks of 500 people, it represents the basis of the calculation.
- Type of event (C): rock concerts, political rallies, sporting events, fairs, airshows, markets — each category has a different risk factor, calibrated on the empirical experience of typical emergency patterns for each type of event.
- Presence of prominent personalities or figures (D): the presence of authorities, heads of state, political or entertainment figures increases operational complexity and the risk profile.
- Potential public order problems (E): contexts with a history of disturbances, social tensions, or rivalries between fan groups are factors that significantly affect the overall health risk.
Audience-related variables:
- Predominant age group of participants
- Density of people in the area (people per square meter)
- Expected emotional condition of the audience (relaxed, excited, aggressive)
- Position of participants (seated, mixed, standing)
These variables reflect a fundamental principle of mass gathering medicine: the audience itself is a determining factor in the event's danger potential.
How to Interpret the Score
The final numerical value should not be read in isolation. It must be contextualized with respect to the thresholds defined by the model, which guide operational decisions on resources and obligations:
Based on the score obtained, it is possible to establish the necessary resources: number of emergency ambulances, transport ambulances, foot patrol responders, and medicalized vehicles or units.
The higher the score, the more the minimum resource thresholds to be guaranteed increase. But the score does not replace the plan: it indicates a floor, a minimum baseline that must be integrated with knowledge of the territory, operator experience, and local specificities.
Applications in Mass Gatherings
The algorithm finds concrete application in a wide variety of events:
- Concerts and music festivals (outdoor and indoor)
- Competitions and sporting events (soccer matches, marathons, cycling races, motorsport events)
- Fairs, markets, and commercial events
- Political demonstrations and rallies
- Religious ceremonies and pilgrimages
- Local festivals and cultural events
- Airshows and civil protection demonstrations
The calculation of medical personnel requirements through the Maurer formula has been successfully applied in complex sporting events, as demonstrated by retrospective analysis of events with thousands of treated patients.
Internationally, the model has been cited among established systems for defining the quality and number of resources to be deployed during an event. The Maurer formula is used to define the quality and number of resources to be employed at the time of the event.
Limitations to Know
No algorithm is infallible, and the Maurer algorithm is no exception. Knowing its limitations is an integral part of professional use.
1. It does not replace clinical and operational judgment. Correctly predicting crowd behavior, such as peaks in people density, is not possible through any algorithm. Planning a health service primarily requires experience; algorithms should be used at most to allow inexperienced individuals to evaluate an already developed concept.
2. Values are indicative, not absolute. The indicated values are exclusively advisory in nature and must be adapted to local conditions, taking into account empirical data from comparable previous events.
3. Tables may vary between documents and contexts. There are versions of the Maurer algorithm with slight differences in the weights assigned to variables or in risk thresholds. Those working in multidisciplinary or international contexts must verify which version is the reference in their operational context.
4. It does not cover extreme or unexpected scenarios. Unforeseeable emergencies (a terrorist attack, a structural accident, a sudden drought) require contingency plans that go beyond the risk profile calculated with this algorithm.
How to Use It Well: 5 Practical Steps
1. Gather event data first. Before opening any table, it is necessary to have concrete information available: site capacity, expected number of visitors, type of event, audience profile, public order context. Approximate data produces unreliable scores.
2. Apply the formula in the official reference version. Use the validated model in your regulatory or operational context. Digital tools (apps and online calculators) exist that automate the calculation and reduce the risk of manual errors.
3. Read the score as a starting point, not an endpoint. The algorithm's result defines a minimum resource threshold. The experienced health professional must assess whether that threshold is sufficient given the specific context.
4. Integrate with other assessment tools. The Maurer algorithm can be paired with other models (for example, the Kölner Algorithmus, which is more granular) or with operational checklists specific to the type of event.
5. Document and share the assessment. The algorithm's value is not only operational, but also communicative and legal. Documentation of the risk assessment process, with the calculated score and planned resources, is an integral part of the health plan to be transmitted to competent authorities.
Conclusion
The Maurer algorithm is one of the most established and accessible tools for health risk assessment in public events. Its strength lies in its simplicity: it allows even those who are not mass gathering physicians to produce a structured risk estimate, communicate it clearly, and plan resources in a transparent and documentable manner.
For EMS nurses, emergency physicians, event medical directors, and event organizers, mastering this tool means being able to approach health planning with a shared, defensible, and prevention-oriented method.
Because the real emergency that can be avoided is the one that is poorly planned in advance.
This article was written for informational and educational purposes. The values and thresholds of the Maurer algorithm may vary based on the versions adopted in different regulatory and operational contexts. It is always recommended to refer to the official guidelines of your territorial emergency service.
