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A simple and effective cooling device based on a thermoelectric cooler was applied to cool the SPME fi ber. The device was used for quantitative extraction of aromatic hydrocarbons in the air. Several factors such as coating temperature, extraction temperature and relative humidity in the laboratory setting were optimized. Comparison of the results between the cold fi ber SPME (CF-SPME) and NIOSH 1501 method on standard test atmosphere indicated a satisfactory agreement. The CF-SPME and SPME method were also compared. The results revealed that CF-SPME has the most appropriate outcome for the extraction of aromatic hydrocarbons from the ambient air. The cold fi ber SPME technique showed good results for several validation parameters. Under the optimized conditions, the limits of detection (LOD) and the limits of quantifi cation (LOQ) ranged from 0.00019 to 0.00033 and 0.0006 to 0.001 ng ml -1 , respectively. The intra-day relative standard deviation (RSD) showed ranging from 4.8 to 10.5%.

In noisy workrooms, exposure conditions such as noise level, exposure duration and use of hearing protection devices are contributory factors to hearing loss. The aim of this study was to determine the effect of exposure conditions on the risk of hearing loss using the Cox model. Seventy workers, employed in a press workshop, were selected to study their hearing threshold using an audiometric test. Their noise exposure histories also were analyzed. The results of the Cox model showed that the job type, smoking and the use of protection devices were effective to induce hearing loss. The relative risk of hearing loss in smokers was 1.1 times of non-smokers The relative risk of hearing loss in workers with the intermittent use of protection devices was 3.3 times those who used these devices continuously. The Cox model could analyze the effect of exposure conditions on hearing loss and provides useful information for managers in order to improve hearing conservation programs.