Effect of ventilation velocity on hexavalent chromium and isocyanate exposures in aircraft paint spraying

Exposure control system performance was evaluated during aircraft paint spraying at a military facility. Computational fluid dynamics (CFD) modeling, tracer gas testing, and exposure monitoring examined contaminant exposure vs. crossflow ventilation velocity. CFD modeling using the RNG k-? turbulence model showed exposures to simulated methyl isobutyl ketone of 294 and 83.6 ppm, as a spatial average of five worker locations, for velocities of 0.508 and 0.381 m/s (100 and 75 fpm), respectively. In tracer gas experiments, observed supply/exhaust velocities of 0.706/0.503 m/s (136/99 fpm) were termed full-flow, and reduced velocities were termed 3/4-flow and half-flow. Half-flow showed higher tracer gas concentrations than 3/4-flow, which had the lowest time-averaged concentration, with difference in log means significant at the 95% confidence level. Half-flow compared to full-flow and 3/4-flow compared to full-flow showed no statistically significant difference. CFD modeling using these ventilation conditions agreed closely with the tracer results for the full-flow and 3/4-flow comparison, yet not for the 3/4-flow and half-flow comparison. Full-flow conditions at the painting facility produced a velocity of 0.528 m/s (104 fpm) midway between supply and exhaust locations, with the supply rate of 94.4 m³/s (200,000 cfm) exceeding the exhaust rate of 68.7 m³/s (146,000 cfm). Ventilation modifications to correct this imbalance created a midhangar velocity of 0.406 m/s (80.0 fpm). Personal exposure monitoring for two worker groups—sprayers and sprayer helpers (“hosemen”)—compared process duration means for the two velocities. Hexavalent chromium (Cr[VI]) exposures were 500 vs. 360 µg/m³ for sprayers and 120 vs. 170 µg/m³ for hosemen, for 0.528 m/s (104 fpm) and 0.406 m/s (80.0 fpm), respectively. Hexamethylene diisocyanate (HDI) monomer means were 32.2 vs. 13.3 µg/m³ for sprayers and 3.99 vs. 8.42 µg/m³ for hosemen. Crossflow velocities affected exposures inconsistently, and local work zone velocities were much lower. Aircraft painting contaminant control is accomplished better with the unidirectional crossflow ventilation presented here than with other observed configurations. Exposure limit exceedances for this ideal condition reinforce continued use of personal protective equipment.     

25家电镀企业中铬污染现状和作业者接触情况

目的 了解电镀企业铬污染现状和工人铬接触情况,寻找有效的铬接触生物标记物,为铬污染的防治提供科学依据.方法 采用整群抽样的方式抽取杭州市25家使用6价铬的电镀企业,进行职业卫生现场调查和空气中铬浓度检测,并对157名铬接触工人和93名非接触工人进行健康调查和体内红细胞中铬含量检测.结果 车间空气中6价铬短时间接触浓度中位数为0.06 mg/m3,范围0.01(检出限)～0.53 mg/m3,合格率89.4％;其中超标岗位均为电镀岗位,中位数0.10 mg/m3,范围0.01(检出限)～0.53 mg/m3,合格率76.3％.铬接触工人红细胞内铬含量的中位数为4.41( 2.50～5.29) μg/L,显著高于对照人群[1.54 (0.61～2.98) μg/L,P＜0.01).按性别、年龄、吸烟、饮酒分层后,除了小于30岁的人群(P=0.11),其余各层内两组间的差异都有统计学意义(P＜0.05).在接触工人中,吸烟者红细胞内铬含量[4.98(2.90～6.37) μg/L]明显高于不吸烟的人群[3.58( 2.25～4.40) μg/L],差异有统计学意义(P＜0.05).结论 杭州市电镀作业环境中存在6价铬污染,电镀作业工人体内铬负荷显著高于对照人群.应降低作业环境中铬浓度,加强工人个体防护,降低6价铬对工人的危害.     

一株除铬(Ⅵ)菌株的筛选和鉴定

目的 分离、驯化和鉴定高效除铬(Ⅵ)菌株。 方法 从某电镀厂聚集区域的环境中采集样品,接种逐步升高铬(Ⅵ)浓度的培养基分离筛选出耐铬(Ⅵ)菌株,通过比较各菌株的除铬(Ⅵ)能力筛选出高效除铬(Ⅵ)菌株,并采用革兰氏染色、生理生化实验、16S rDNA等技术进行菌种鉴定。 结果 菌株CQMU-1的除铬效果最好;CQMU-1为革兰氏阴性球菌或短杆菌;能在500mg/L的含铬(Ⅵ)LB肉汤中生长,但生长受抑制;其最适生长pH为7.0～8.0,温度为20～35℃,好氧,化能异养,能利用大多数碳水化合物;经16S rDNA鉴定CQMU-1为产碱菌属。 结论 筛选出1株高效除铬(Ⅵ)菌株,可用于去除环境中铬(Ⅵ)污染。     

机械通气期间发热的原因和处理

目的　调查重症监护病房机械通气病人发热的原因 ,探讨其处理对策和预防措施。方法　回顾性分析 1997年 7月～ 2 0 0 2年 12月机械通气发热病人 76例。结果　机械通气期间发热的原因有 :感染性发热 6 0例 (78.9% ) ,其中呼吸机相关性肺炎 (VAP) 4 0例 (5 2 .6 % ) ,鼻窦炎 5例 (6 .6 % ) ,原发革兰阴性菌败血症 5例 (6 .6 % ) ,导管相关性败血症 3例 (3.9% ) ,难辨梭菌性结肠炎 3例 (3.9% ) ,脑脓肿 2例 (2 .6 % ) ,尿路感染 2例 (2 .6 % ) ;非感染性发热 16例 (2 1.1% ) ,其中脑出血 6例 (7.9% ) ,输血后发热 3例 (3.9% ) ,药物热 2例 (2 .6 % ) ,急性坏死型胰腺炎 2例(2 .6 % ) ,肺癌 2例 (2 .6 % ) ,心肌梗死 1例 (1.3% )。非感染性发热很少超过 38.9℃ ,且持续时间多小于 72h。结论　机械通气间发热的原因有感染性和非感染性 ,大多数为感染性的 ,尤其以VAP最常见。合理的处理需要一套全面的、系统的诊治程序 ,首先排除非感染性原因 ,然后确定感染的部位和病原体。     

Exposure to airborne nano-titanium dioxide during airless spray painting and sanding

The objectives of the study were to measure and characterize exposure to airborne nanoscale titanium dioxide during airless spraying and sanding of a nano-enabled paint, and to evaluate the effectiveness of dust capture methods in reducing airborne nanoparticle concentrations. A tradesperson performed the work activities in an environmentally controlled chamber. Samples were collected in the tradesperson's breathing zone and in surrounding areas to assess bystander exposure. Filter-based samples were analyzed using gravimetric methods, scanning electron microscopy, and energy dispersive spectroscopy. Differential particle count data were obtained by means of a scanning mobility particle sizer. Local exhaust ventilation provided statistically significant reductions of airborne nanoparticle concentrations during sanding. Sanding the paint after drying with a handheld power sander generated relatively low levels of airborne titanium dioxide. In contrast, task-based exposure measurements collected during the initial airless spray application of the nano-enabled paint suggested a potential for occupational exposures to exceed the time-weighted average exposure limit for ultrafine titanium dioxide recommended by the National Institute for Occupational Safety and Health. Painters applying nano-enabled coatings may have little recourse but to rely, in some instances, on lower tiers of the hierarchy of controls, such as personal protective equipment. In light of these findings, employers and industrial hygienists should characterize exposures and implement the hierarchy of controls to ensure painters are sufficiently protected.     

还原型谷胱甘肽预处理对单肺通气患者围手术期炎性因子和自由基的影响

目的　探讨还原型谷胱甘肽(GSH)预处理对单肺通气患者围手术期炎性因子和自由基的影响.方法选择30例择期行肺叶切除术的肺癌患者,按随机数字表法分为GSH组和对照组,每组15例.GSH组于麻醉诱导后单肺通气前静脉输注GSH　30　mg/kg,对照组静脉输注等量0.9％氯化钠.于麻醉诱导前(T0)、单肺通气30　min(T1)、单肺通气60　min(T2)、恢复双肺通气60　min(T3)和术后2　h(T4)采集桡动脉血,测定血浆肿瘤坏死因子(TNF)-α、白细胞介素(IL)-8、丙二醛(MDA)水平和超氧化物歧化酶(SOD)活性.结果T2～T4时两组MDA较T0时显著升高(P＜　0.05)[　GSH组T0～T4分别为(3.5±0.6)、(3.8±0.8)、(4.7±1.1)、(6.1±1.2)、(6.4±0.9)　mol/L;对照组T0～T4分别为(3.7±0.5)、(4.1±0.6)、(5.9±1.2)、(7.4±1.0)、(7.8±1.1)　mol/L],但GSH组显著低于对照组(P＜0.05).T2～T4时对照组SOD活性较T0时降低(P＜0.05),且低于GSH组(P＜0.05).T1～T4时两组TNF-α、IL-8较T0时显著升高(P＜0.05),但GSH组T2～T4时TNF-α及T1～T4时IL-8显著低于对照组(P＜0.05).结论　GSH　30　mg/kg预处理可减轻单肺通气患者肺的炎性反应及脂质过氧化程度.     

Childhood adversity and traumatic exposures during deployment as predictors of mental health in Australian military veterans

Objective : To examine whether the relationship between traumatic exposure on deployment and poor mental health varies by the reported level of childhood adversity experienced in Australian military veterans deployed to the Bougainville or East Timor military operations. Methods : Cross‐sectional self‐reported survey data were collected in 2008 from 3,564 Australian military veterans who deployed to East Timor or Bougainville on their deployment experiences, health and recall of childhood events. Multivariable logistic regression was used to investigate the association between childhood adversity, deployment exposures and mental health. Results : The most common childhood adversity reported was ‘not having a special teacher, youth worker or family friend who looked out for them while growing up’. On average, responders reported experiencing 3.5 adverse childhood experiences (SD 2.7) and averaged 5.3 (SD 4.9) traumatic exposures on deployment. Both childhood adversity and traumatic exposures on deployment were associated with higher odds of poorer mental health. However, there was no evidence that level of childhood adversity modified the association between traumatic exposure and mental health. Conclusions/Implications : These findings suggest that military personnel who recalled a higher level of childhood adversity may need to be monitored for poor mental health and, if required, provided with appropriate support.     

Profiling stainless steel welding processes to reduce fume emissions,hexavalent chromium emissions and operating costs in the workplace

Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr⁶⁺). Elemental manganese, nickel, chromium, iron emissions per unit length of weld, and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered, and analyzed by inductively coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr⁶⁺. GMAW processes used were Surface Tension Transfer, Regulated Metal Deposition, Cold Metal Transfer, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr⁶⁺ ranged from 50–7800 µg/min, and Cr⁶⁺ generation rates per g electrode ranged from 1–270 µg/g. Elemental Cr generation rates spanned 13–330 µg/g. Manganese emission rates ranged from 50–300 µg/g. Nickel emission rates ranged from 4–140 µg/g.

Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as five times the cost of a typical SMAW welding machine.

The results show that all of the GMAW processes in this study can substantially reduce fume, Cr⁶⁺, manganese and costs relative to SMAW, the most commonly used welding process, and several have exceptional capabilities for reducing emissions.     

全凭静脉麻醉对胸腔镜手术患者单肺通气期间肺内分流和动脉血氧合的影响

目的观察全凭静脉麻醉对胸腔镜手术患者单肺通气期间肺内分流和动脉血氧合的影响。方法选择40例择期行胸腔镜手术的患者,随机分成两组（n=20）：全凭静脉麻醉组（A组）和静吸复合麻醉组（B组）。全麻诱导插管后,A组以异丙酚靶控输注,B组以七氟醚吸入,维持BIS在40～60,PetCO2在30～35mmHg范围内。观察并记录患者侧卧位双肺通气10min（TLV）、侧卧位单肺通气15min（OLV＋15）、30min（OLV＋30）,60min（OLV＋60）各时间点的平均动脉压（MAP）、心率（HR）、脉搏血氧饱和度（SpO：）和平均气道压（Paw）;在相应时间点抽取动脉血和右心房血进行血气分析,计算肺内分流率（Qs／Qt）;观察并记录患者发生低血压、心动过缓、低氧血症、苏醒延迟及苏醒期躁动等不良反应的发生情况。结果在OLV期间,两组患者的Qs／Qt明显增加,B组大于A组（34．2±5vs28．8±2;38．4±8VS32．1±6;37．1±2VS29．5±2）;两组患者的Pa02明显降低,但A组PaO2均大于B组（177±88vs125±63;150-4-65vs110±67;188±69vs128±52）,差异有统计学意义（P〈0．05）。在OLV后15min、30min两时间点,A组患者的MAP低于B组（72±10VS88±14;74±12vs89±10）,差异有统计学意义（P〈0．05）。A组低血压、苏醒延迟的发生率高于B组（10例VS4例;9例vs2例）,B组苏醒期躁动的发生率高于A组（9例VS3例）,差异有统计学意义（P〈0．05）。结论与七氟醚静吸复合麻醉比较,异丙酚全凭静脉麻醉能有效减少胸腔镜手术患者单肺通气期间的肺内分流,改善动脉血氧合,有利于低氧血症的预防。     

胸腔镜手术单肺通气期间非通气侧肺不同处理方法对动脉血氧合肺内分流的影响

目的观察胸腔镜手术单肺通气(OLV)期间非通气侧肺不同处理方法对动脉血氧合肺内分流的影响。方法将30例行胸腔镜手术的患者分为三组:A组将非通气侧肺的支气管导管旷置于大气中;B组向非通气侧肺的支气管导管吹氧;C组将非通气侧肺的支气管导管出口处接上一负压吸引管。在OLV前、OLV30min、OLV60min分别采动脉血做血气分析并计算肺内分流率(Qs/Qt)。结果动脉血氧分压(PaO2)在OLV60min时A组下降明显,B、C组与A组比较差异有统计学意义(P<0.05);Qs/Qt在OLV30min时B、C组与A组比较差异有统计学意义(P<0.05),OLV60min时B、C组与A组比较差异有统计学意义(P<0.01)。结论B组与C组的非通气侧肺处理方法都能降低肺内分流,提高动脉血氧合能力,但C组的方法更方便胸腔镜手术术中的操作。     

单肺通气不同水平呼气末正压对胸腔镜肺大疱切除术患者血气分析及血流动力学的影响

目的 探讨单肺通气时应用不同水平的呼气末正压（PEEP）对胸腔镜肺大疱切除术患者术中血气分析及血流动力学的影响.方法 将78例行胸腔镜肺大疱切除术患者按随机数字表法分为三组,每组26例：Ⅰ组双肺通气后仅给予单肺间歇正压通气（IPPV）,Ⅱ组双肺通气后给予单肺IPPV加PEEP5 cmH2O（1 cmH2O=0.098 kPa）,Ⅲ组双肺通气后给予单肺IPPV加PEEP 10 cmH2O.记录并比较三组平卧位双肺通气、侧卧位双肺通气、单肺通气10和30 min的血气分析和血流动力学.结果 三组患者脉搏血氧饱和度均维持在0.99～ 1.00.三组各时间点pH值、剩余碱、动脉血二氧化碳分压（PaCO2）、HCO3-比较差异均无统计学意义（P＞0.05）.Ⅱ、Ⅲ组单肺通气10,30 min动脉血氧分压（PaO2）明显高于Ⅰ组[（336.2±113.2）,（348.5±109.7） mmHg（1mmHg=0.133 kPa）比（285.0±103.5） mmHg,（357.6±104.0）,（358.9±103.2） mmHg比（276.0±107.2） mmHg],差异有统计学意义（P＜0.05）,但均在正常范围内,Ⅱ组和Ⅲ组比较差异无统计学意义（P＞0.05）.三组各时间点心率、平均动脉压、左心室射血时间、体循环血管阻力比较差异均无统计学意义（P＞0.05）.Ⅱ组和Ⅲ组单肺通气10,30 min每搏输出量、心输出量明显低于本组平卧位双肺通气、侧卧位双肺通气及Ⅰ组同期,差异均有统计学意义（P＜0.05）,但均在正常范围内,Ⅱ组和Ⅲ组比较差异无统计学意义（P＞0.05）.结论 双肺通气后给予单肺IPPV加PEEP 5 cmH2O在胸腔镜肺大疱切除术中能维持满意的PaO2和PaCO2,血流动力学变化不明显;但PEEP 5 cmH2O较仅IPPV能进一步提高PaO2,而PEEP 10 cmH2O却没有进一步提高PaO2.     

胸腔镜手术单肺通气期间非通气侧肺不同处理方法对动脉血氧合肺内分流的影响

目的观察胸腔镜手术单肺通气（OLV）期间非通气侧肺不同处理方法对动脉血氧合肺内分流的影响。方法将30例行胸腔镜手术的患者分为三组：A组将非通气侧肺的支气管导管旷置于大气中；B组向非通气侧肺的支气管导管吹氧；C组将非通气侧肺的支气管导管出口处接上-负压吸引管。在OLV前、OLV30win、OLV60win分别采动脉血做血气分析并计算肺内分流率（Qs／Qt）。结果动脉血氧分压（Pa02）在OLV60min时A组下降明显，B、C组与A组比较差异有统计学意义（P〈0．05）；Qs／Qt在OLV30win时B、C组与A组比较差异有统计学意义（P〈0．05），OLV60win时B、C组与A组比较差异有统计学意义（P〈0．01）。结论B组与C组的非通气侧肺处理方法都能降低肺内分流，提高动脉血氧合能力，但C组的方法更方便胸腔镜手术术中的操作。     

2020—2021年新冠感染疫情期间烟台市公共场所集中空调通风系统卫生状况调查

目的 监测评估2020—2021年新冠感染疫情期间烟台市公共场所集中空调通风系统卫生状况。方法 2020—2021年对116家具有集中空调通风系统的公共场所进行了检测，检测项目包括集中空调送风细菌总数、真菌总数、β溶血性链球菌，风管内表面细菌总数、真菌总数和新冠病毒，冷却水和冷凝水中的嗜肺军团菌等项目。结果 2020—2021年两年间公共场所集中空调通风系统检测的合格率分别为39.0%(30/77)、56.4%(22/39),差异无统计学意义(χ²=3.187,P=0.074);不同场所的合格率差异有统计学意义(χ²=11.86,P<0.05),其中商场的合格率最高(65.0%),而娱乐场所和医院合格率较低，分别为0.0%、33.3%;送风和风管内表面的检测样品中均未检出β溶血性链球菌和新冠病毒。空调送风中细菌总数的检测合格率相对较高，为98.2%,风管内表面细菌总数和真菌总数合格率比较低，分别为65.5%和71.6%。结论 应加强公共场所集中空调通风系统清洗消毒的监管力度，消除集中空调卫生安全隐患。     

The simultaneous detection of trivalent & hexavalent chromium in exhaled breath condensate: A feasibility study comparing workers and controls

The analytical method outlined in this feasibility study has been used to show that trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) can be detected and measured in exhaled breath condensate (EBC) samples. EBC samples and urine samples were collected from a cohort of 58 workers occupationally exposed to hexavalent chromium compounds and 22 unexposed volunteers (control group). Levels of Cr(III) and Cr(VI) were determined in EBC samples and total chromium levels were determined in urine samples. Pre and post working week samples for both EBC and urine were collected in tandem. Total chromium in urine samples was analysed by inductively coupled plasma mass spectrometry (ICP-MS). Analysis of Cr(III) and Cr(VI) in EBC samples used a hyphenated micro liquid chromatography (μLC) system coupled to an ICP-MS. Separation was achieved using an anion exchange micro-sized column. The results showed that the occupationally exposed workers had significantly higher levels of Cr(III) and Cr(VI) in their EBC samples than the control group, as well as higher levels of total chromium in their urine samples. However, for the exposed workers no significant difference was found between pre and post working week EBC samples for either Cr(III) or Cr(VI). This study has established that Cr(III) and Cr(VI) can simultaneously be detected and measured in ‘real’ EBC samples and will help in understanding inhalation exposure.