Calculating Injury and Illness Incidence Rates Form

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OSHA Injury and Illness Incidence Rate Calculator

Taken from your OSHA 300 Log (total of columns G, H, I, and J).
Actual hours worked by all employees during the calendar year (exclude leave/vacation).

Total Recordable Incident Rate (TRIR):

function calculateIncidenceRate() { var numCases = parseFloat(document.getElementById('num_cases').value); var totalHours = parseFloat(document.getElementById('total_hours').value); var resultBox = document.getElementById('incidence_result_box'); var resultValue = document.getElementById('incidence_value'); var interpretation = document.getElementById('incidence_interpretation'); if (isNaN(numCases) || numCases < 0) { alert('Please enter a valid number of cases.'); return; } if (isNaN(totalHours) || totalHours <= 0) { alert('Please enter a valid number for total hours worked (must be greater than 0).'); return; } // OSHA Formula: (Number of Injuries & Illnesses X 200,000) / Employee Hours Worked var rate = (numCases * 200000) / totalHours; resultValue.innerHTML = rate.toFixed(2); resultBox.style.display = 'block'; interpretation.innerHTML = 'This rate represents the number of injuries and illnesses per 100 full-time workers per year.'; }

Understanding the Injury and Illness Incidence Rate (TRIR)

The Total Recordable Incident Rate (TRIR) is a standard mathematical formula used by the Occupational Safety and Health Administration (OSHA) to evaluate a company's safety performance. It allows businesses of different sizes to be compared on equal footing by normalizing the data based on a standard population of 100 full-time employees.

How the Calculation Works

The formula uses a base of 200,000 hours. This number represents the total hours that 100 employees would work in a year (100 employees × 40 hours per week × 50 weeks per year). By using this multiplier, the resulting rate tells you how many recordable incidents occurred for every 100 workers.

The Formula:
(Number of Injuries and Illnesses × 200,000) ÷ Total Employee Hours Worked = Incidence Rate

Example Calculation

Imagine a manufacturing plant that had 4 recordable injuries last year. The total hours worked by all staff (including overtime) was 160,000 hours.

  • Step 1: 4 (cases) × 200,000 = 800,000
  • Step 2: 800,000 ÷ 160,000 (hours) = 5.0
  • Result: The plant's TRIR is 5.0.

Why Track This Metric?

Monitoring your incidence rate is crucial for several reasons:

  1. Benchmarking: Compare your safety performance against industry averages published by the Bureau of Labor Statistics (BLS).
  2. Identifying Trends: If your rate increases year-over-year, it may indicate a breakdown in safety protocols.
  3. Insurance & Contracts: Many clients and insurance providers use TRIR as a qualifying factor for awarding contracts or determining premiums.
  4. OSHA Compliance: High incidence rates can trigger OSHA inspections or placement in the Severe Violator Enforcement Program.

What Qualifies as a "Recordable Case"?

According to OSHA, a recordable injury or illness includes any work-related fatality, any work-related injury or illness that results in loss of consciousness, days away from work, restricted work, or transfer to another job, or any work-related injury or illness requiring medical treatment beyond first aid.

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