Assessing Organizational Risk: Utilizing the 4 Ds to Safeguard Against Airborne Infectious Diseases

C2C - January 2-02-2024 - ES (5)

The last few years have taught us many things about the spread of infectious diseases like COVID-19, RSV, and measles in indoor environments. And it’s these lessons that we can use to ensure that our places of work are and continue to be safe places for our workers, customers, and communities. Many of the steps you can take to help keep buildings and the people in them safer and healthier are simple and effective. They can be adjusted to meet the current situation or existing infectious disease risk. 

First and foremost, when implementing prevention measures to protect your workplace, it is important that you monitor the global (World Health Organization or WHO), federal (CDC), state, and local guidelines for changes or updates in recommendations, disinfection strategies, worker protections, and other risk management best practices as they become available for any currently contagious airborne diseases. You’ll want to utilize those recommendations in parallel to the suggestions you find in this blog post when dealing with an airborne virus. 

Viruses that transmit as airborne particles, such as the viruses that cause COVID-19, flu, and measles, pose such a significant risk as they can squeeze into small places, nearly 10,000 times smaller than a human hair, travel long distances, up to 20 to 30 feet, and stay active in the air for at least 4 hours. 

When you think about viral aerosols or viruses that transmit as airborne particles, think of them as water moving in a stream. Like the water, they will find the easiest path from one point to the next. With a rock or log in a stream, the water in the stream will find a path around it. Our job is to add as many logs, rocks, and barriers – through things like ventilation, workplace policies, distance, and masks – to help protect ourselves and others. Figuring out how to assess the risk of getting infected with or spreading airborne diseases in any situation is your number one tool in keeping yourself and others healthy and safe.

We don’t know how much of a virus that’s in the air will make us ill, or how bad it could be. And we can’t find out which type of virus we caught until we start feeling sick. But we do know how people catch airborne infectious diseases, how they spread, and how we can reduce the potential for exposure. How? By using the four Ds and implementing them with a simple scale to help you manage risk.


How long will the employee or others be indoors? The longer time spent indoors, the more the air becomes filled with invisible airborne particles. The risk of transmission while indoors is much higher than in outdoor spaces. Without the aid of sunlight to stop the virus or wind to dilute it, the small particles of the virus can remain active for hours. Even with the best HVAC systems, it is impossible to recreate the outdoor experience in an indoor space, allowing the virus to build up over time.


How many people are in the space? How many are not vaccinated? How many are sick and not showing signs? How many are not wearing masks? As these numbers increase, so does the risk. Scientific research proves masks help protect the wearer and those around them from infection and viral spread. The more unmasked, unvaccinated, or infected people without showing signs, the more likely the disease will spread. Vaccination does not provide immunity from infection, but it does decrease the risk of getting infected and makes it less severe when you do.


Being outdoors is relatively safe compared to being indoors, thanks to how easy it is to dilute the virus due to more open space, moving air, and the aid of sunlight to stop the virus. One way to reduce the amount of virus in an enclosed space is by diluting the air. Add outdoor, filtered, or recirculated air into the enclosed space using a good HVAC system. The lack of an HVAC system in older buildings or aging systems results in greater risk to those in the building. However, in some cases, just opening windows to allow the outdoor air flow can help dilution.


How far or near are people around one another? Infected individuals exhale a high amount of viral particles, which is why being close to an infected person increases your risk of infection. The relative distance between people is a risk factor to consider. The further you are away from the infected person, the lower your risk of getting infected.

Remembering the 4 Ds will help you and your employees identify their risk level and define your organization’s steps to keep them protected. We have developed a simple tool that allows you to quickly and easily determine the potential risk of exposure in your built space. Feel free to test it out now and refer to it for different situations or scenarios you might encounter in your workplace. 

This short quiz can tell you your organization’s potential risk and what you can do in your workplace to help address it. We will ask you questions about duration and density, as they will allow you to determine your risk. For example, how long are people in your building space typically indoors? (Duration) or how many people are in your building space, how many people are or are potentially sick and not showing signs, and are or can be assumed to be unvaccinated, if relevant to the current infectious disease, and how many of them are not wearing masks? (Density). 

You may be wondering, what about the two remaining Ds? Dilution and Distance can help manage the risk after it has been determined. Your results will outline clear and specific actions to help manage the risk of transmission through dilution and distance. Take a few minutes to answer these questions to determine your organization’s risk.

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About us

The Commit to C.A.R.E. provides free resources and tools for businesses to safeguard their employees and communities from infectious diseases.

All tools developed under this project have been created with the needs of a nonscientific and non-medical audience in mind.

El Compromiso C.A.R.E. proporciona recursos y herramientas gratuitos para que las empresas protejan a sus empleados y comunidades de enfermedades infecciosas.

Todas las herramientas desarrolladas bajo este proyecto han sido creadas con las necesidades de una audiencia no científica y no médica en mente.