The results of a NIOSH exposure assessment of 1,3-butadiene (106990) (BD) monomer, polymer, and end user industries were presented. The study was performed in two phases: 11 monomer, 17 polymer, and two end user factories were included in a walk through survey, and industrial hygiene surveys were conducted at four monomer, five polymer, and two end user facilities. A novel method developed by NIOSH was used for sampling as low as 0.005 parts per million (ppm) BD/25 liter sample. Personal and area samples were collected by portable low flow air sampling pumps and analyzed by high resolution gas chromatography. Airborne BD exposure concentrations were obtained for various job categories for personal samples. In the monomer industry, a total of 211 samples were obtained. The greatest short term BD levels were found with open loop sampling and cylinder voiding. The greatest potential exposure occurred for workers required to handle or transport BD containers. For the 584 samples collected for the polymer industry, full shift exposure levels ranged up to 42.9ppm and short term exposures reached up to 280ppm. The highest full shift exposure occurred for a maintenance technician working on a BD compressor, and the greatest short term exposure was found for a process technician working in the unloading area. In all samples from the end user industries, the BD concentrations were below the limit of detection. Overall, BD exposures ranged from below 0.005ppm to 374ppm, while 3.7% of the samples had more than 10ppm, 7.8% contained between 2 and 10ppm, and 88.5% had less than 2ppm. The exposure levels were observed to be well below the OSHA permissible exposure limit of 1,000ppm. A new OSHA standard that would reduce exposure to 2ppm was proposed. The authors recommend a closed loop sampling system for quality control, the use of retro fitting pumps for BD containers, conversion to 100% magnetic gauges for rail car monitoring, improved laboratory ventilation and worker training, and a new NIOSH sampling and analytical method for the reduction of potential exposure to butadiene.