You are here:

# Occupational (OSHA) and Environmental Hazards/Incident Rate

Question
QUESTION: Hi Mike;

I am working as a Manager - Occupational Health & Safety in a large scale tyre manufacturing company with more than 8,000 employees located in Sri Lanka.

We are using AFR (Accident Frequency Rate) to monitor the recordable accident rate with the formula (# of recordable accidents/Monthly completed worked hours)* 200,000. We use this figure/Rate to get an idea of accident rate of the last month.

My question is, is that correct to use monthly worked hours while multiplying by 200,000 which considering worked hours per year ? if it is incorrect,please explain how to calculate " monthly accident rate ".

Regards,

Channa.

Question: Hi Mike; I am working as a Manager - Occupational Health & Safety in a large scale tyre manufacturing company with more than 8,000 employees located in Sri Lanka. We are using AFR (Accident Frequency Rate) to monitor the recordable accident rate with the formula (# of recordable accidents/Monthly completed worked hours)* 200,000. We use this figure/Rate to get an idea of accident rate of the last month. My question is, is that correct to use monthly worked hours while multiplying by 200,000 which considering worked hours per year ? if it is incorrect, please explain how to calculate " monthly accident rate ". Regards, Channa.

Answer: You are correct. The calculation for the Monthly Incident Rate (MIR) is:

MIR = (Number of incidents for the month times 200,000) divided by the hours worked for the month

The 200,000 is a constant that was specified by OSHA (Occupational Safety and Health Administration) and represents the supposed hours worked by a company of 100 persons in a year's time assuming no overtime and two weeks of vacation per employee. OSHA felt it more closely represented the average workplace in the U.S. than the old Accident Frequency Rates which used the constant of 1,000,000 and different definitions of what was to be counted. The results makes more sense when you use the numeric results (such as 5.6) with the proper units (such as 5.6 Recordable Incidents per 100 Employees per Year). Unfortunately this is seldom done and most people (including safety professionals) just talk about an "Incident Rate of 4.6 without any defining units. Trying to get the managers and supervisors to think of the number as something other than an abstract number was a constant challenge.

Michael Brown, CSP Retired

---------- FOLLOW-UP ----------

QUESTION: Thank you Sir,you explained clearly for what I asked. Please see follow table for further clarify,

Month          January   February   March
# of Accidents          2      5          3
Worked hours completed        214,108   195,220          198,864

Accident Frequency Rates(AFR)  1.9          5.1          3.0

AFR = (# of accidents/worked hours completed)*200,000.

I have two questions to clear,

1). Can't i get AFR per 100 employees per month instead of per year since i am considering worked hours completed per month. ?

2). Is that correct / what is explanation of calculating AFR value for the month as cumulative accidents & worked hours completed ?
As a example;
AFR for the month January  = (2/214,108)*200,000 = 1.9

AFR for the month February = {(2+5)/(214,108 + 195,220)}*200,000 = 3.42

AFR for the month March = {(2+5+3)/(214,108 + 195,220 + 198,864)}*200,000 = 3.28

Cont....

Regards;

Channa.

Subject: Incident Rate

Question:
Thank you Sir, you explained clearly for what I asked. Please see follow table for further clarify,

Month          January   February   March
# of Accidents          2      5          3
Worked hours completed        214,108   195,220          198,864
Accident Frequency Rates(AFR)  1.9          5.1          3.0
AFR = (# of accidents/worked hours completed)*200,000.
I have two questions to clear,

1). Can't I get AFR per 100 employees per month instead of per year since I am considering worked hours completed per month. ?

2). Is that correct / what is explanation of calculating AFR value for the month as cumulative accidents & worked hours completed ?
As a example;

AFR for the month January  = (2/214,108)*200,000 = 1.9
AFR for the month February = {(2+5)/(214,108 + 195,220)}*200,000 = 3.42
AFR for the month March = {(2+5+3)/(214,108 + 195,220 + 198,864)}*200,000 = 3.28
Cont.... Regards; Channa.

Answer: You are correct. If I were writing a report using the examples you give I would state: "For January we had an AFR of 1.9 Accidents per 100 employees; For February we had an AFR of 5.1 Accidents per 100 employees; and for March we had an AFR of3.0 Accidents per 100 employees. This gives us a Year-To-Date (which can apply each month as the year progresses) AFR of 3.28 Accidents per 100 employees." As you can see it is up to the writer to establish the time period for the AFR since the calculations are the same and are correct for your illustration. In my last position I accumulated the monthly and year-to-date rates for a number of locations and published the results monthly. If this all seems confusing don't be alarmed. Many safety managers struggle with this process and still manage to foul it up occasionally.

Michael Brown, CSP Retired

Occupational (OSHA) and Environmental Hazards