Levels of benzene,toluene and xylene at workplaces in enterprises within a district of Shenzhen from 2009 to 2013

Objective To observe the levels of benzene,toluene and xylene at workplaces of enterprises located in a district of Shenzhen. Methods The monitoring data of benzene,toluene and xylene at workplaces from different enterprises from 2009 to 2013 were collected and analyzed,and the volatile constituents of 152 common organic solvents were analyzed. Results Benzene was detected in 1.26% to 5.94% samples yearly and maximum 0.86% sample were not compliant with the national standard. Toluene was detected in 21.34% to 69.01% samples yearly and maximum 5.71% samples were not compliant with the national standard. Xylene was detected in 9.17% to 35.14% samples yearly and maximum 1.40% samples were not compliant with the national standard. There were trends that the detectable rates of benzene,toluene and xylene at workplaces all decreased gradually year after year (χ²=45.32,713.16,317.04,P < 0.01 or 0.05).There were trends that the over-standard rates of benzene,toluene and xylene at workplaces decreased gradually year after year (χ²=15.80,26.69,P < 0.01).The detection rates of benzene,toluene and xylene in 152 organic solvents were 2.63%,46.71% and 37.50%,respectively. Conclusion The pollution of benzene,toluene and xylene in the air of workplaces had basically been brought under control,but the monitoring of benzene still need strengthening.