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Course 708 - OSHA Recordkeeping Basics

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Injury/Illness Incidence Rates

How does your company compare?

It's useful to be able to evaluate your company's injury-and-illness experience over time to compare it's experience with that of your industry as a whole. To do that you need to compute your incidence rate. Incidence rates can, to a certain degree, help you identify problems in your workplace or progress made toward preventing work-related injuries and illnesses. This is also the same information used by OSHA to calculate potential penalty reductions, so I guess that makes it important too.

Are incidence rates really important?

Incidence rates can be useful as a measure in evaluating your organization's safety management system. Incidence rates measure "what's already happened." They primarily measure how many fatalities, injuries, and accidents have occurred over time. Do not rely solely on incidence rates: here's why.

Trailing indicators measure the "effect"

Incidence rates are "trailing indicators." They record and summarize historical data. Incidence rates do not measure the actual "causes" of injury and illness incidents: they measure the "effect," not the cause, of the incident. Relying solely on incidence rates to improve your safety management system is not effective. It's like driving down the road and looking in the rear-view mirror to stay in your lane. Other examples of trailing indicators are: workers compensation rates, equipment failure rates, unsafe behavior rates. However the most common trailing indicator remains the incidence rate.

Leading indicators measure the "cause"

Actually, it's more important to emphasize the measurement of "leading indicators." These are the thoughts, decisions, behaviors, and activities that have the most direct influence on safety management system design, development and deployment. Incidence rates for fatalities, injuries, and accidents can be used to determine if they are leading indicators.

As long as you measure both leading and trailing indicators, you're on the right track.

Incidence Rate

An incidence rate is the number of recordable injuries and illnesses occurring among a given number of full-time workers (usually 100 full-time workers) over a given period of time (usually one year). It's important to note that in Europe the incident rate may be based on 500 full-time workers.

How do I calculate an incidence rate?

You can quickly and easily compute an occupational injury and illness incidence rate for all recordable cases or for cases that involved days away from work and days of restricted work using the following steps:

  • Calculate total recordable injuries and illnesses: To find out the total number of recordable injuries and illnesses that occurred during the year - count the number of line entries on your OSHA Form 300 or refer to the OSHA Form 300A and sum the entries for columns (G), (H), (I), and (J).

  • Calculate total workhours: The number of hours all employees actually worked during the year - refer to OSHA Form 300A and optional worksheet to calculate this number.

  • Calculate the DART Rate: The "DART" (Days Away, Restricted, or Job Transferred) is used to express the incident rate. To determine the DART Rate, count the number of line entries on your OSHA Form 300 that received a check mark in columns (H) and (I), or refer to the entry in columns (H) and (I) on the OSHA Form 300A.

The Equation

You can compute the incidence rate for all recordable cases of injuries and illnesses using the following equation:

(The 200,000 figure in the formula represents the number of hours 100 employees working 40 hours per week, 50 weeks per year would work and provides the standard base for calculating incidence rates.)

You can compute the incidence rate for recordable cases involving days away from work, days of restricted work activity, or job transfer using the following formula:


Equation Example

For instance, if you have 50 employees who work a total of 100,000 hours during the year and have experienced 10 recordable injuries, the DART rate would be (10 ÷ 100,000) x 200,000 = 20. So, in this example, the DART rate indicates there are 20 days away, restricted, or transferred injuries per 100 employees. The number of employees doesn't matter. The total number of injuries and the total number of hours the employees work during the year are the two important figures entered into the formula.

You can use the same formula to calculate incidence rates for other variables such as cases involving restricted work activity (Column (I) on OSHA Form 300A), cases involving skin disorders (Column (M-2) on OSHA Form 300A), etc. Just substitute the appropriate total for these cases, from OSHA Form 300A, into the formula in place of the total number of injuries and illnesses.

Click to Enlarge

Comparing Incidence Rates

The Bureau of Labor Statistics (BLS) conducts a survey of occupational injuries and illnesses each year and publishes incidence-rate data by various classifications (e.g., by industry, by employer size, etc.). You can get the data at or by calling a BLS regional office to look at OSHA reports.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Which of the following is NOT true concerning injury and illness rates?

2. Which of the following best defines an "incidence rate"?

3. To find out the number of injuries and illnesses that involved days away from work and days of restricted work (DART) using the OSHA 300 Log, you would refer to the entries in columns _____.

4. Which formula below is used to determine the DART rate?

5. What is the DART Rate for a company that had 10 injuries and 80 employees who worked a total of 150,000 hours during the year?

Have a great day!

Important! You will receive an "error" message unless all questions are answered.