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Risk Matrix Calculations – Severity, Probability, and Risk Assessment

Risk Matrix Calculations – Severity, Probability, and Risk Assessment
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April 23, 2018

Resource: Blog Industry: All industries
Tags: EHS Management, Risk Management

Safety Professionals use a risk matrix to assess the various risks of hazards (and incidents), often during a job hazard analysis. Understanding the components of a risk matrix will allow you and your organization to manage risk effectively and reduce workplace illnesses and injuries, including exposures to Coronavirus (COVID-19). Check out the three components of the risk matrix; severity, probability, and risk assessment that we utilize in Vector EHS Management software below.

No time to read? You can download our Risk Matrix Calculation Guide to review it at your convenience:

1. Severity

Severity is the amount of damage or harm a hazard could create and it is often ranked on a four point scale as follows:

  • Catastrophic - 4 Operating conditions are such that human error, environment, design deficiencies, element, subsystem or component failure, or procedural deficiencies may commonly cause death or major system loss, thereby requiring immediate cessation of the unsafe activity or operation.
  • Critical - 3 Operating conditions are such that human error, environment, design deficiencies, element, subsystem or component failure or procedural deficiencies may commonly cause severe injury or illness or major system damage thereby requiring immediate corrective action.
  •  Marginal - 2 Operating conditions may commonly cause minor injury or illness or minor systems damage such that human error, environment, design deficiencies, subsystem or component failure or procedural deficiencies can be counteracted or controlled without severe injury, illness or major system damage.
  •  Negligible - 1 Operating conditions are such that personnel error, environment, design deficiencies, subsystem or component failure or procedural deficiencies will result in no, or less than minor, illness, injury or system damage.

2. Probability

Probability is the likelihood of the hazard occurring and it is often ranked on a five point scale:

  • Frequent - 5 Likely to occur often in the life of an item
  • Probable - 4 Will occur several times in the life of an item
  • Occasional - 3 Likely to occur some time in the life of an item.
  • Remote - 2  Unlikely but possible to occur in the life of an item.
  • Improbable - 1 So unlikely, it can be assumed occurrence may not be experienced.

Risk matrices come in many shapes and sizes. For more information on how to build a risk matrix that's right for your project, see our more detailed guide.

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3. How to Use the Risk Assessment

The Risk Assessment Values are determined by multiplying the scores for the Probability and Severity values together. The higher the risk assessment, the greater the overall risk for the project. This method helps balance the weight of severity and probability, as you can see in the following chart that displays the default risk assessment values:

5x4 risk matrix

Numerous EHS professionals throughout North America rely on Vector EHS Management Software to manage workplace hazards.

Learn more about how we can help.

Download our free Risk Matrix Guide

EHS Hazards 1

Setting Control Measures for Risk Mitigation

After you’ve evaluated the risks of a project, you can prioritize which risk controls to implement first.

All risk mitigation activities should be clearly defined; objective, not subjective; and have specific, measurable outcomes.

Hazard identification and risk management should be processes of continuous improvement. Your organization’s risks may change over time, so you should periodically review and update your risk matrix.

Risk management tools can save health and safety professionals valuable time and resources.

Check out our hazards product information page to learn more how the Vector EHS Management software can assist you in tracking, reporting and analyzing your risks.

Hazard Analysis Software

Risk Assessments for Coronavirus (COVID-19)

As the coronavirus (COVID-19) pandemic continues to impact daily operations throughout the globe, EHS managers have been tasked with taking important measures to protect the health and safety of their workforce.

One of the ways in which EHS professionals can identify which workers are at greatest risk of being exposed to the virus is through following risk assessment processes.

In the agency’s guidance on preparing workplaces for COVID-19, the Occupational Safety and Health Administration (OSHA) has categorized job functions into four risk exposure levels. We’ve fleshed out these four divisions in the following paragraphs.  When you’re determining what probability values would be useful to set for your risk matrix, it’s a good idea to use these 4 categories as a starting point.

Very High Exposure Risk

According to OSHA, workers with a very high probability of exposure include:

  • Healthcare workers (e.g., doctors, nurses, dentists, paramedics, emergency medical technicians) performing aerosol-generating procedures (e.g., intubation, cough induction procedures, bronchoscopies, some dental procedures and exams, or invasive specimen collection) on known or suspected COVID-19 patients.
  • Healthcare or laboratory personnel collecting or handling specimens from known or suspected patients.
  • Morgue workers performing autopsies, which generally involve aerosol-generating procedures, on the bodies of people who are known to have, or suspected of having, COVID-19 at the time of their death.

High Exposure Risk

Workers with a high probability of exposure include:

  • Healthcare delivery and support staff (e.g., doctors, nurses, and other hospital staff who must enter patients’ rooms) exposed to known or suspected COVID-19 patients. (Note: when such workers perform aerosol-generating procedures, their exposure risk level becomes very high.)
  • Medical transport workers (e.g., ambulance vehicle operators) moving known or suspected COVID-19 patients in enclosed vehicles.
  • Mortuary workers involved in preparing (e.g., for burial or cremation) the bodies of people who are known to have, or suspected of having, COVID-19 at the time of their death.

Medium Exposure Risk

  • Medium exposure risk jobs include those that require frequent and/or close contact with (i.e., within 6 feet of) people who may be infected with COVID-19, but who are not known or suspected patients.
  • In areas where there is ongoing community transmission, workers in this category may have contact with the general public (e.g., in schools, high-population-density work environments, and some high-volume retail settings).
  • In areas without ongoing community transmission, workers in this risk group may have frequent contact with travelers who may return from international locations with widespread COVID-19 transmission.

Lower Exposure Risk

Lower exposure risk jobs are those that do not require contact with people known to be, or suspected of being, infected nor frequent close contact with (i.e., within 6 feet of) the general public. Workers in this category have minimal occupational contact with the public and other coworkers.

Severity of COVID-19

At this stage, it’s difficult to predict the effects that the virus may have upon an individual. Thus far, epidemiological evidence suggests that COVID-19 manifests as a non-severe disease in most cases. However, according to the most recent data compiled by the Centers for Disease Control and Prevention (CDC), some groups are at higher risk of becoming severely ill from the virus. When determining values for the Severity component of your matrix, these groups should be categorized into the value assigned the highest number of points. Your other severity values may vary depending on the demographics of your workforce.

Risk of Becoming Severely Ill

Groups at risk of becoming seriously ill from COVID-19 include:

  • People aged 65 years and older
  • People who live in a nursing home or long-term care facility
  • People with chronic lung disease or moderate to severe asthma
  • People who have heart disease with complications
  • People who are immunocompromised. Many conditions can cause a person to be immunocompromised, including cancer treatment, bone marrow or organ transplantation, immune deficiencies, poorly controlled HIV or AIDS, and prolonged use of corticosteroids and other immune-weakening medications.
  • People of any age with severe obesity or certain underlying medical conditions, particularly if not well controlled, such as those with diabetes, renal failure, or liver disease

People who are pregnant should be monitored since they are known to be at risk with severe viral illness. However, to date data on COVID-19 has not shown increased risk.

Controls to Prevent Exposure to Coronavirus (COVID-19)

Once you've completed your risk assessments, you can begin to put controls in place to mitigate exposures as best as possible.

OSHA has put together guidance for workplaces on the appropriate engineering and administrative controls, as well as personal protective equipment (PPE) for workers with lower, medium, and high exposure risks. We've also put together a few tips on how EHS managers can develop plans to deal with the virus in the workplace.

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