An integrated job exposure matrix for electrical exposures of utility workers

Electric utility workers may be exposed to any combination of magnetic fields, electric fields, nuisance shocks (from spark discharges and continuous currents), imperceptible contact currents, and electrical injuries. Collectively these exposures are referred to as EMF Factors. Previous occupational exposure assessments have mainly characterized the magnetic field, with less attention to the electric field. Nuisance shocks and electrical injuries, though palpable, have received little to no attention. This article presents a prototype job exposure matrix that addresses exposure to all EMF Factors taking into account job category, work environment, and occupied environment. Exposures for all factors were classified into three ordinal levels for 22 job categories. Electric and magnetic field exposures were classified by the geometric mean of daily average of personal exposure measurements. Although relatively sparse, survey data on nuisance shocks were adequate for exposure assignment by job category and indicate that the frequency of these exposures has diminished over time. The least information was available for imperceptible contact currents that are associated with electric field exposures and small contact voltages. Data for electrical injuries by job category were derived from the Electric Power Research Institute Occupational Health Surveillance Database, with exposure assignments based on combined injury rates for flash burn and electric shock/electrocution. The highest exposures for all EMF Factors are essentially limited to four job categories that work on or close to electrical equipment: (1) cable splicers, (2) electricians, (3) line workers, and (4) substation operators.