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SAFETYSafety: Conversion from AIR to AFRIn line with the data published by the Health and Safety Executive, the Safety KPI is the AccidentIncidence Rate (AIR) which is number of reportable accidents per 100, 000 employed per year. Themethod of calculating AIR is described in the Methods of Measurement. However, someorganisations collect safety data as the Accident Frequency Rate (AFR) which gives the accident rateper 100,000 person hours worked. Unlike the AIR, the AFR formula makes allowance for variations inpart-time work or overtime. AFR is calculated as follows:AFR =Number of reportable accidentsNumber of person-hours worked including self-employed and sub-contractorsx 100,000Formulae for converting one from the other are given below.AIR to AFR (simplified) =AIR2,000AFR (simplified) to AIR = AFR x 2,000AFR (measured) to AIR = AFR x (Number of hours worked in the year by a typicalfull-time worker)The calculation above uses an assumption of 2,000 hours worked per person during the year. Usingthis figure for all those employed gives a simplified AFR calculation which makes no allowance forvariations in working weeks. Using the actual number of hours worked by the entire workforce will bemore accurate for those companies where this information is available.Safety: Calculation of Project AIR PerformanceOrganisations wishing to calculate safety (AIR) at a project rather than company level should usethe formula:Performance (AIR) safety =Number of reportable accidents during projectAverage number employed during the project includingx100,000x52Project durationself-employed and sub-contractors(weeks)or they should calculate the project Accident Frequency Rate (AFR) and convert this to the projectAccident Incidence Rate (AIR) using one of the conversion formulae given above.Care should be taken when comparing project results against KPI graphs of companyperformance as the results could be misleading.2006 UK KPIs - Handbook 23