Dose-response relationship between lung function and chest imaging response to silica exposures in artificial stone manufacturing workers.

BACKGROUND: Occupational exposure to artificial stone, a popular material used for countertops, can cause accelerated silicosis, but the precise relationship between silica dose and disease development is unclear. OBJECTIVES: This study evaluated the impact of silica exposure on lung function and chest imaging in artificial stone manufacturing workers. METHODS: Questionnaire and spirometry assessments were administered to workers in two plants. A high-exposure subset underwent further evaluation, including chest CT and DLco. Weighting factors, assigned as proxies for silica exposure, were based on work tasks. Individual cumulative exposures were estimated using area concentration measurements and time spent in specific areas. Exposure-response associations were analyzed using linear and logistic regression models. RESULTS: Among 65 participants, the mean cumulative silica exposure was 3.61 mg/m3-year (range 0.0001 to 44.4). Each 1 mg/m3-year increase was associated with a 0.46% reduction in FVC, a 0.45% reduction in FEV1, and increased lung function abnormality risk (aOR = 1.27, 95% CI = 1.03-1.56). Weighting factors correlated with cumulative exposures (Spearman correlation = 0.59, p < 0.0001), and weighted tenure was associated with lung function abnormalities (aOR = 1.04, 95% CI = 1.01-1.09). Of 37 high-exposure workers, 19 underwent chest CT, with 12 (63%) showing abnormal opacities. Combining respiratory symptoms, lung function, and chest X-ray achieved 91.7% sensitivity and 75% specificity for predicting chest CT abnormalities. CONCLUSION: Lung function and chest CT abnormalities occur commonly in artificial stone workers. For high-exposure individuals, abnormalities on health screening could prompt further chest CT examination to facilitate early silicosis detection.

The effect of cumulative noise exposure on distortion product otoacoustic emissions.

OBJECTIVE: This study aimed to identify the characteristics of distortion product otoacoustic emissions (DPOAEs) that can be used to differentiate noise-induced hearing loss (NIHL) from age-related hearing loss. A potential index to detect NIHL was defined in terms of its susceptibility to cumulative noise exposure but not to age. DESIGN: In this cross-sectional cohort study, a job-exposure matrix was used to calculate the cumulative noise exposure. Multivariate linear regression models were used to examine how age and cumulative noise exposure associated with DPOAEs at individual frequencies after adjusting for hypertension, dyslipidaemia, tobacco use and alcohol consumption. STUDY SAMPLE: The pure-tone audiometry and DPOAEs data collected from 239 male workers in a steel factory. RESULTS: DPOAEs and DPOAE signal-to-noise ratios (SNRs) at all frequencies were found to be correlated with age, and those at 2, 3, 4 and 6 kHz were correlated with both age and noise exposure. The difference between DPOAE SNR at 1 and 3 kHz showed significant correlation with noise exposure but not with age. CONCLUSIONS: The results showed that this DPOAE index, the DPOAE SNR at 1 kHz minus the DPOAE SNR at 3 kHz, could add values to audiometric evaluation of NIHL.

Effect of Implementing Electronic Toll Collection in Reducing Highway Particulate Matter Pollution.

Highway vehicle emissions can result in adverse health problems to nearby residents and workers, especially during traffic congestion. In response, the policy to implement electronic toll collection (ETC) has helped alleviate traffic congestion, as compared to manual toll collection (MTC) and has led to reduced air pollution and improved public health. However, the effect of ETC in reducing particulate matter polluting the air is not well understood, especially in the ultrafine particle (UFP) range (particle diameter <100 nm). To the best of our knowledge, this is the first study to investigate how ETC affects the traffic pattern and air quality, especially UFP and PM2.5. We selected a site in Tainan, Taiwan, and measured UFP and PM2.5 concentrations before and after the construction of the ETC system. The computed traffic volumes during peak travel periods (7:00 AM to 9:00 AM and 4:00 PM to 6:00 PM) respectively, accounted for approximately 23-25% and 14-18% before and after the implementation of ETC, indicating that peak traffic volumes were more homogeneous after ETC. Moreover, the results indicate that the full implementation of ETC can help reduce UFP number concentrations and PM2.5 mass concentrations in the highway downwind area by 4 × 103 #/cm3 and 20.5 µg/m3, respectively. After the full implementation of the ETC, significant reductions in both the UFP number concentration and PM2.5 mass concentration were seen. Furthermore, excessive lifetime cancer risks (ELCR) from exposure to PM2.5 and UFP together were reduced 49.3% after the implementation of the ETC. Accordingly, ETC not only helps alleviate traffic congestion but also reduces traffic emissions and lifetime cancer risk for people living or working near highways.

Estimation of respiratory heat flows in prediction of heat strain among Taiwanese steel workers.

International Organization for Standardization 7933 standard provides evaluation of required sweat rate (RSR) and predicted heat strain (PHS). This study examined and validated the approximations in these models estimating respiratory heat flows (RHFs) via convection (C res) and evaporation (E res) for application to Taiwanese foundry workers. The influence of change in RHF approximation to the validity of heat strain prediction in these models was also evaluated. The metabolic energy consumption and physiological quantities of these workers performing at different workloads under elevated wet-bulb globe temperature (30.3 ± 2.5 °C) were measured on-site and used in the calculation of RHFs and indices of heat strain. As the results show, the RSR model overestimated the C res for Taiwanese workers by approximately 3 % and underestimated the E res by 8 %. The C res approximation in the PHS model closely predicted the convective RHF, while the E res approximation over-predicted by 11 %. Linear regressions provided better fit in C res approximation (R 2 = 0.96) than in E res approximation (R 2 ≤ 0.85) in both models. The predicted C res deviated increasingly from the observed value when the WBGT reached 35 °C. The deviations of RHFs observed for the workers from those predicted using the RSR or PHS models did not significantly alter the heat loss via the skin, as the RHFs were in general of a level less than 5 % of the metabolic heat consumption. Validation of these approximations considering thermo-physiological responses of local workers is necessary for application in scenarios of significant heat exposure.

Emissions of Nanoparticles and Gaseous Material from 3D Printer Operation.

This study evaluated the emissions characteristics of hazardous material during fused deposition modeling type 3D printing. Particulate and gaseous materials were measured before, during, and after 3D printing in an exposure chamber. One ABS and two PLA (PLA1 and PLA2) cartridges were tested three times. For online monitoring, a scanning mobility particle sizer, light scattering instrument, and total volatile organic compound (TVOC) monitor were employed and a polycarbonate filter and various adsorbent tubes were used for offline sampling. The particle concentration of 3D printing using ABS material was 33-38 times higher than when PLA materials were used. Most particles were nanosize (<100 nm) during ABS (96%) and PLA1 (98%) use, but only 12% were nanosize for PLA2. The emissions rates were 1.61 × 10(10) ea/min and 1.67 × 10(11) ea/g cartridge with the ABS cartridge and 4.27-4.89 × 10(8) ea/min and 3.77-3.91 × 10(9) ea/g cartridge with the PLA cartridge. TVOCs were also emitted when the ABS was used (GM; 155 ppb, GSD; 3.4), but not when the PLA cartridges were used. Our results suggest that more research and sophisticated control methods, including the use of less harmful materials, blocking emitted containments, and using filters or adsorbents, should be implemented.

Cancer incidence of Taiwanese shipbreaking workers who have been potentially exposed to asbestos.

BACKGROUND: Shipbreaking remains one of the most dangerous jobs worldwide. Shipbreaking workers are exposed to many hazardous chemicals, especially asbestos. Unfortunately, long-term follow-up studies of cancer incidence patterns in shipbreaking workers are lacking. This study examines whether there is an increased risk of cancer among male shipbreaking workers over a 24-year follow-up period. METHODS: 4155 male shipbreaking worker's information was retrospectively collected from Kaohsiung's Shipbreaking Workers Union database from 1985. The study cohort was linked to the Taiwan Cancer Registry from 1985 to 2008 for new cancer cases. The expected number of cancers for shipbreaking workers was calculated by using the age (5-year intervals) and calendar time-specific annual rates of cancer incidence with reference to the general population of Taiwan from 1985 to 2008. Standardized incidence ratios (SIRs) were calculated as relative risk estimates. The hazard ratio (HR) for cancer was calculated for the shipbreaking workers with Total Exposure Potential Scores for asbestos. RESULTS: After consideration of a 5-year latency period, an elevated incidence of overall cancer (N=368; SIR=1.13 (1.01-1.25)), oral cavity cancer (N=83; SIR=1.99 (1.58-2.46)), and trachea, bronchus, and lung cancers (N=53; SIR=1.36 (1.02-1.78)) was found among male shipbreaking employees. Moreover, mesothelioma cases were found in those who had the occupation of flame cutter. The high asbestos exposure group was associated with an increased SIR of developing overall cancer and oral cancer, whether we considered a 5-year or 10-year latency period. CONCLUSION: Asbestos-related diseases, including lung cancer and mesothelioma, were seen in excess in these shipbreaking workers and some cases appeared to have a dose-dependent relationship. Preventative measures among male shipbreaking workers should be researched further.

Evaluation of particle and volatile organic compound emissions during the use of 3D pens.

This study investigated particle and volatile organic compound (VOC) emission rates (ER) from 3D pens, which are increasingly popular in children's toys. Nine filaments and two 3D pens were evaluated using a flow tunnel, a scanning mobility particle sizer, a proton-transfer-reaction time-of-flight mass spectrometer for particles, and a thermal desorption-gas chromatography-mass spectrometer for VOCs. Results showed that the ERs varied with the pen type, filament, and brand. The particle ER was highest for acrylonitrile butadiene styrene (ABS), followed by polylactic acid (PLA) and polycaprolactone (PCL). Notably, ERs of 83 % and 33 % of ABS and PLA filaments exceeded the maximum allowable particle ER (MAER; 5 × 109 particles/min) for 3D printers but were lower than the VOC MAER (173 µg/min in the office). Different filaments emitted diverse VOCs; ABS emitted styrene and benzene, PLA emitted lactide, and PCL emitted phenol. While particle ERs from 3D pens were comparable to those from printers, the total VOC ERs from 3D pens were slightly lower. Caution is warranted when using 3D pens because of potential health risks, especially their prolonged use, proximity to the breathing zone, and usage by children. This study highlights the need for considering particles and VOCs when assessing the safety of 3D pens, emphasizing awareness of potential hazards, particularly in child-oriented settings.

Obliterative bronchiolitis in fibreglass workers: a new occupational disease?

RATIONALE AND OBJECTIVES: Obliterative bronchiolitis (OB) is a rare disease with a small number of established occupational aetiologies. We describe a case series of severe OB in workers making glass-reinforced plastics. METHODS: Workplace exposures were the likely cause after the independent diagnosis of OB in two workers laying up the fibreglass hulls of yachts; the second worker took over the job of the first after he left following a lung transplant. Presentation of these two cases at international meetings led to others identifying similar workers. MAIN RESULTS: We identified six workers with good evidence of OB. All were involved in preparing fibreglass with styrene resins, five as boat builders laying up fibreglass hulls and one during cooling-tower fabrication. The disease came on rapidly without unusual acute exposures. Two patients had lung transplants, while another died while waiting for one. Histology confirmed OB in the four with biopsies/post-mortem examinations or explanted lungs. CONCLUSIONS: A rare, potentially fatal disease occurring in six workers laying up fibreglass with styrene resins from five different worksites suggests that work exposures were the cause of their OB. The precise agent responsible awaits identification.

Pulmonary function, respiratory symptoms, and dust exposures among workers engaged in early manufacturing processes of tea: a cohort study.

BACKGROUND: To evaluate pulmonary function and respiratory symptoms in workers engaged in the early manufacturing processes of tea and to identify the associated factors, we conducted a study in a tea production area in Taiwan. METHODS: We recruited tea workers who engaged in the early manufacturing process in the Mountain Ali area in Taiwan and a comparison group of local office workers who were matched for age, gender, and smoking habits. We performed questionnaire interviews, pulmonary function tests, skin prick tests, and measurement of specific IgE for tea on the participants and assessed tea dust exposures in the tea factories. RESULTS: The 91 participating tea workers had higher prevalence of respiratory symptoms than the comparison group (32 participants). Among tea workers, ball-rolling workers had the highest prevalence of symptoms and the highest exposures of inhalable dusts. At baseline, tea workers had similar pulmonary functions as the comparison group, but compared to the other tea workers ball-rolling workers had a lower ratio of the 1-second forced expiratory volume to forced vital capacity (FEV1/FVC) and a lower maximal mid-expiratory flow rate expressed as% of the predicted value--MMF (%pred). A total of 58 tea workers participated in the on-site investigation and the cross-shift lung function measurements. We found ball-rolling yielded the highest inhalable dust level, panning yielded the highest respirable dust level, and withering yielded the lowest levels of both dusts. Ball-rolling also yielded the highest coarse fraction (defined as inhalable dusts minus respirable dusts), which represented exposures from nose to tracheobronchial tract. During the shift, we observed significant declines in pulmonary function, especially in ball-rolling workers. Multiple regressions showed that age, height, work tasks, coarse fraction, and number of months working in tea manufacturing each year were independent predictors of certain pulmonary function parameters in tea workers. CONCLUSIONS: Tea workers engaged in early manufacturing processes of tea have higher prevalence of respiratory symptoms and pulmonary function impairment, which might be related to tea dust exposures, especially the coarse fraction.

Effects of gene-environmental interaction on noise-induced hearing threshold levels for high frequencies (HTLHF).

In this study we assessed the interaction between glutathione S-transferase (GST) genetic polymorphisms and noise exposures, with regard to their effect on the hearing threshold levels for high frequencies (HTLHF). Research participants comprised 347 male workers, and each participant's cumulative noise exposure was determined using a job-exposure matrix. Approximately 64.6% of the participants' exposure in L(eq-8 h) was above 90 dBA. The mean HTLHF was 32.1 dB. A significant dose-response relationship was found between noise exposure and HTLHF. We further converted the estimated total noise exposure level over each participant's job history to a noise exposure level that corresponded to a 40-year exposure (L(eq-40y)). After we had adjusted the results for age, we found that workers carrying GSTM1 null, GSTT1 null, and GSTP1 Ile(105)/Ile(105) genotypes were susceptible to the HTLHF when their L(eq-40y) were above 90 dBA. Therefore, GST genetic polymorphisms might affect HTLHF only when workers are exposed to high noise levels.

Application of Standardized Proportional Mortality Ratio to the Assessment of Health Risk in Relatively Healthy Populations: Using a Study of Cancer Risk in Telecommunication Workers with Excess Exposure to Acid Mists as an Example.

When a study population is relatively healthy, such as an occupational population, epidemiological studies are likely to underestimate risk. We used a case study on the cancer risk of workers with exposure to acid mists, a well-documented carcinogen, to demonstrate that using proportional mortality ratios (PMRs) is more appropriate than mortality ratios in assessing risk in terms of mortality. The study included 10,229 employees of a telecommunication company who worked in buildings with battery rooms. In these buildings, the battery rooms had the highest levels of sulfuric acid in the air (geometric mean = 10.7 µg/m3). With the general population in Taiwan as a reference, a decreased standardized mortality ratio (0.42, p < 0.01) from all causes combined, between 1 January 1985 and 31 December 1996, was observed, indicating a healthy worker effect. When we reanalyzed the data using standardized PMR, elevated risks were observed for all cancers combined (1.46, p = 0.01) and cancers of the digestive organs and peritoneum (1.61, p = 0.02), especially stomach cancer (2.94, p = 0.01). The results showed that PMR can detect increases in mortality when a study population is generally healthier than the comparison population and call for further studies on the possible carcinogenic effects of low-level acid mist exposures on the stomach.

Physical and psychological stress along with candle fumes induced-cardiopulmonary injury mimicking restaurant kitchen workers.

Restaurant kitchens are work areas where involve strict and hierarchal environments that promote opportunity for bullying and workplace aggression and violence. These physical and psychological stress and fumes ultimately trigger severe occupational stress by disrupting the body's homeostasis that might induce cardiopulmonary injury. The study aimed to investigate the physical and psychological stress and candle fumes on cardiopulmonary injury in an animal model mimicking a restaurant kitchen worker. Social disruption stress (SDR) mice were exposed to scented candle fumes (4.5 h/d, 5 d/wk) in an exposure chamber for 8 weeks. Exposure to burning scented candles failed to reduce serum corticosterone level and increased proinflammatory cytokines levels and NF-ƙB activity in the lung. In addition, burning scented candle fumes synergistically increased SDR-induced serum LDH, CPK, CKMB levels, proinflammatory cytokines production as well as NF-ƙB activation in the lung and heart. Further, cardiac HIF-1α and BNP levels were also increased. We conclude that the physical and psychological stress along with candle fumes might induce cardiopulmonary injury in mice. These results could be extrapolated to restaurant kitchen workers.

Respiratory health effects of the fiberglass-reinforced plastic lamination process in the yacht-building industry.

Objectives Fiberglass-reinforced plastics (FRP) manufacturing has been related to cases of severe airway obstruction and elevated risk of respiratory mortality. But the specific job content risk is not clear. This study evaluated the respiratory health effects of the FRP lamination process. Methods A questionnaire was used to evaluate respiratory symptoms of workers in two yacht-building plants. Pre-shift (07:30-08:30 hours) and post-shift (17:00-18:00 hours) lung function was measured, while post-shift induced sputum was collected on the first day of the week. The participants were grouped into FRP laminators and non-laminators. Linear and logistic regression was used to investigate the effects of the lamination process on lung function. Results Laminators had a higher prevalence of chronic cough, lower pre-shift forced expiratory volume in first second (FEV1) and FEV1/force vital capacity (FVC) (-3.3% and -1.5%), lower post-shift FVC and FEV1 (-3.6% and -4.9%), and larger post-shift reduction of FVC (-2.1%) compared to non-laminators. The laminators also had higher risk of early obstructive and overall (obstructive plus restrictive) lung function impairment, and post-shift reduction of FVC >10% [odds ratio (OR) 5.98, 4.98, and 3.87, respectively). They also had higher percentages of neutrophils and lymphocytes in the induced sputum. Conclusion Laminators should undergo regular check-ups of respiratory symptoms and lung function. Further toxicologic studies are warranted to identify the specific causal agent in the FRP lamination process.

Using a modified electrical aerosol detector to predict nanoparticle exposures to different regions of the respiratory tract for workers in a carbon black manufacturing industry.

The present study was set out to characterize nanoparticle exposures in three selected workplaces of the packaging, warehouse, and pelletizing in a carbon black manufacturing plant using a newly developed modified electrical aerosol detector (MEAD). For confirmation purposes, the MEAD results were compared with those simultaneously obtained from a nanoparticle surface area monitor (NSAM) and a scanning mobility particle sizer (SMPS). We found that workplace background nanoparticle concentrations were mainly coming from the outdoor environment. Size distributions of nanoparticles for the three selected process areas during the work hours were consistently in the form of bimodel. Unlike nanoparticles of the second mode (simply contributed by the process emissions), particles of the first mode could be also contributed by the forklift exhaust or fugitive emissions of heaters. The percents of nanoparticles deposited on the alveolar (A) region were much higher than the other two regions of the head airway (H), tracheobronchial (TB) for all selected workplaces in both number and surface area concentrations. However, significant differences were found in percents of nanoparticles deposited on each of the three regions while different exposure metrics were adopted. Both NSAM and MEAD obtained quite comparable results. No significant difference can be found between the results obtained from SMPS and MEAD after being normalized. Considering the MEAD is less expensive, less bulky, and easy to use, our results further support the suitability of using MEAD in the field for nanoparticle exposure assessments.

Establishing aerosol exposure predictive models based on noise measurements--using concrete drilling as an example.

This study used a full scale mockup of a concrete drilling simulator to simulate drilling processes in an exposure chamber. Six drilling conditions were selected with rotating speeds and drill bit sizes varied from 265 to 587 rpm and 16 to 32 mm, respectively. For each drilling condition, the emitted noise power spectrums were measured and dust exposure concentrations of the fractions of the total (C(tot)), inhalable (C(inh)), thoracic (C(tho)), and respirable (C(res)) were estimated. We find that neither the resultant dust exposure levels nor the noise levels can be explained simply by the involved drilling mechanical energy. By dividing the emitted noise power spectrums into the high and low frequency noise (i.e., W(H) and W(L)), we find that 86.3%, 85.6%, 81.5%, and 77.6% variations of C(tot), C(inh), C(tho), and C(res) could be explained by the combination of W(H) and W(L), respectively. We also find that the emissions of coarse particles and W(L) were possibly contributed by two mechanisms of the impact wear and brittle fracture wear, whereas fine particles and W(H) could be contributed by the mechanism of abrasive wear. Although the predictive models obtained from this study could not be directly used in other dust emission sources, the developed methodology would be beneficial to industries in the future for aerosol exposure assessment, particularly when conducting conventional personal aerosol samplings is not possible in the field.

Assessing inhalatory and dermal exposures and their resultant health-risks for workers exposed to polycyclic aromatic hydrocarbons (PAHs) contained in oil mists in a fastener manufacturing industry.

This study first assessed workers' inhalatory and dermal exposures to polycyclic aromatic hydrocarbons (PAHs) contained in oil mists. Then, their resultant lung cancer and skin cancer risks were estimated. Finally, control strategies were initiated from the health-risk management aspect. All threading workers in a fastener manufacturing plant were included. 16 inhalatory and 88 dermal PAH exposure samples were collected. Results show that the inhalatory gas phase total PAH exposure level (8.60 x 10(4) ng/m3) was much higher than that of particle phase (2.30 x 10(3) ng/m3). Workers' mean inhalatory exposure level (8.83 x 10(4) ng/m3) was lower, but its corresponding 1-sided upper 95% confidence level (UCL1,95% = 1.02 x 10(5) ng/m3) was higher than the time-weighted average permissible exposure level (PEL-TWA) regulated in Taiwan for PAHs (1.00 x 10(5) ng/m3). The mean whole body total PAHs dermal exposure levels was 5.44 x 10(6) ng/day and the top five exposed surface areas were lower arm, hand, upper arm, neck, and head/front. The estimated lifetime skin cancer risk (9.72 x 10(-3)) was lower than that of lung cancer risk (1.64 x 10(-2)), but both were higher than the significant risk level (10(-3)) defined by the US Supreme Court in 1980. The installation of a local exhaust ventilation system at the threading machine should be considered as the first priority measurement because both lung and skin cancer risks can be reduced simultaneously. If the personal protection equipment would be adopted in the future, both respiratory protection equipment and protective clothing should be used simultaneously.

Exposure and health-risk assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) for sinter plant workers.

This study was set out to assess polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) exposures and health-risk impact posed on sinter plant workers. One sinter plant located in southern Taiwan was selected and their workers were divided into four exposure groups based on their work tasks, including raw material charging workers, sintering grate workers, shredding workers, and others. Results show that their mean total PCDD/F and the corresponding total I-TEQ exposure levels shared the same trend as: shredding workers>others>sintering grate workers>raw material charging workers. For all selected exposure groups, their PCDD/F exposures were dominated by the particle phase contents. Congener profiles of the gaseous+particle phase PCDD/Fs were found with more fractions of high chlorinated congeners than low chlorinated congeners. The lifetime average daily doses (LADDs) and their resultant excess cancer risks (ECRs) found for sinter plant workers were higher than those residents living at the residential area and rural area, but were lower than those living at the nearby of the selected sinter plant, urban area, industrial area. Considering ECRs of the sinter plant workers were still higher than 10(-6) suggesting the need for adopting proper control measurements for reducing workers' PCDD/F exposures, particularly for those sinter zone workers.

Elemental and organic carbon exposure in highway tollbooths: a study of Taiwanese toll station workers.

The carbon composition of fine particles (PM(2.5)) from traffic exhausts may play a role in adverse health effects. The objective of this study was to assess the concentrations of elemental and organic carbon in PM(2.5) in traffic exhausts from different types of vehicles in the booths of Taiwanese toll station workers and estimate the relations between traffic density and carbon concentrations. Tollbooth indoor monitoring samples were collected for 10 days to assess the 8 h integrated PM(2.5) concentration. Particle samples were analyzed for the content of total carbon, and elemental, and organic carbon. The mean carbon concentrations in the bus and truck lanes were [total: 167.7 microg/m(3) (SD 79.8 microg/m(3)); elemental: 131.7 (66.2); organic: 36.0 (25.8)], substantially higher compared with the car lanes with cash payment [39.2 (29.5); 20.2 (19.5); 19.2 (14.6)] and the car lanes with ticket payment [34.1 (26.1); 15.8 (17.6); 18.5 (12.2)]. The increase in elemental carbon concentration per vehicle in the bus and truck lane was 14 and 9 times greater than that of car lanes of ticket payment and car lanes of cash payment. The mass fraction of carbonaceous species in PM(2.5) accounted for 54% in bus and truck lanes, whereas the corresponding figure was 30-31% for car lanes. Elemental carbon is an important component of diesel exhaust. Workers in toll stations are exposed to high levels of both elemental and organic carbon.

Characterization of PAHs exposure in workplace atmospheres of a sinter plant and health-risk assessment for sintering workers.

This study first measured concentrations of polycyclic aromatic hydrocarbons (PAHs) in four selected workplace atmospheres, including the raw materials inlet, sintering grate, rough roll shredder and control room, and the outdoor environment of a sinter plant. Then, PAHs exposures and their resultant health-risks were assessed for sintering workers. We found that total PAH concentrations of the three selected sintering process areas were higher than that of the control room. The above results could be explained by the filtration effect of the air conditioning device installed inside the control room. PAH homologue distributions of the three selected sintering process areas were significantly different from that of the outdoor environment suggesting that PAHs found in the sintering workplace atmospheres were mainly contributed by process fugitives. Total PAH exposure levels were lower than the current permissible exposure limits, thus revealing that sintering workers are not a high risk group for long-term effects attributable to PAHs. Moreover, the lung cancer risks associated with the above PAH exposures were lower than the significant risk level defined by US Supreme Court further confirming that their exposures could be acceptable at this stage.