Petroleum refinery workers and service station attendants are continually exposed to benzene, toluene and xylene (BTX) due to the emission of volatile aromatic hydrocarbons (VAHs) in these environments. The objective of this study was to evaluate the health risk from exposure to BTX in service stations and benzene in petroleum refinery environments by using probabilistic techniques as well as development of exposure guidelines for risk to human health with benzene. The health risk resulting from exposure to BTX in service stations and benzene exposure in petroleum refineries was carried out by using data from scientific literature from 21 countries globally based on 23 research papers. The data were collected and collated into different scenarios for service stations and petroleum refinery environments based on activity, location and occupation and were plotted as cumulative probability distributions (CPD) plots. There were 6 scenarios for service station environments and 4 scenarios for petroleum refinery environments. The exposure data from service stations and petroleum refinery environments were calculated in terms of average daily dose (ADD) and lifetime average daily dose (LADD).