Physiological responses and air consumption during simulated firefighting tasks in a subway system

Professional firefighters (33 men, 3 women), ranging in age from 30 to 53 years, participated in a simulation of a subway system search and rescue while breathing from their self-contained breathing apparatus (SCBA). We tested the hypothesis that during this task, established by expert firefighters to be of moderate intensity, the rate of air consumption would exceed the capacity of a nominal 30-min cylinder. Oxygen uptake, carbon dioxide output, and air consumption were measured with a portable breath-by-breath gas exchange analysis system, which was fully integrated with the expired port of the SCBA. The task involved descending a flight of stairs, walking, performing a search and rescue, retreat walking, then ascending a single flight of stairs to a safe exit. This scenario required between 9:56 and 13:24 min:s (mean, 12:10 ± 1:10 min:s) to complete, with an average oxygen uptake of 24.3 ± 4.5 mL kg(-1) min(-1) (47 ± 10 % peak oxygen uptake) and heart rate of 76% ± 7% of maximum. The highest energy requirement was during the final single-flight stair climb (30.4 ± 5.4 mL kg(-1) min(-1)). The average respiratory exchange ratio (carbon dioxide output/oxygen uptake) throughout the scenario was 0.95 ± 0.08, indicating a high carbon dioxide output for a relatively moderate average energy requirement. Air consumption from the nominal "30-min" cylinder averaged 51% (range, 26%-68%); however, extrapolation of these rates of consumption suggested that the low-air alarm, signalling that only 25% of the air remains, would have occurred as early as 11 min for an individual with the highest rate of air consumption, and at 16 min for the group average. These data suggest that even the moderate physical demands of walking combined with search and rescue while wearing full protective gear and breathing through the SCBA impose considerable physiological strain on professional firefighters. As well, the rate of air consumption in these tasks classed as moderate, compared with high-rise firefighting, would have depleted the air supply well before the nominal time used to describe the cylinders.     

Nitrosyl-hemoglobin formation in the blood of animals exposed to nitric oxide.

Animals were exposed to nitric oxide (NO) in order to study its biological effect. First a method was developed to exclude nitrogen dioxide formed during exposure of NO. Nitrosyl-hemoglobin (NOHb) in the blood of mice, rats, and rabbits exposed to NO was determined by electron spin resonance spectrometry at -100C. The content of NOHb in the blood of the mouse reached the maximum (0.13% of the total hemoglobin) 20 minutes after the exposure was begun and thereafter a state of equilibrium was maintained. The NOHv level decreased to one half in several minutes after the mouse was removed to a filtered air environment. Dose-response relationship was observed between gas concentrations and the maximum NOHb level.     

Nitrosyl-Hemoglobin Formation in the Blood of Animals Exposed to Nitric Oxide

? Animals were exposed to nitric oxide (NO) in order to study its biological effect. First a method was developed to exclude nitrogen dioxide formed during exposure of NO. Nitrosyl-hemoglobin (NOHb) in the blood of mice, rats, and rabbits exposed to NO was determined by electron spin resonance spectrometry at -100 C.

The content of NOHb in the blood of the mouse reached the maximum (0.13% of the total hemoglobin) 20 minutes after the exposure was begun and thereafter a state of equilibrium was maintained. The NOHb level decreased to one half in several minutes after the mouse was removed to a filtered air environment.

Dose-response relationship was observed between gas concentrations and the maximum NOHb level.     

多功能离子净化舒适性空调系统的应用

多功能离子净化舒适性空调系统是采用微孔金属吊项大温差送风的变风量系统，微孔金属吊顶既是一个孔板送风口，又是辐射换热的冷却顶板。空气处理机内配置的智能型离子空气净化装置在去除空气中的TVOC与自然茵方面有特殊功效，使系统能在保持合格的室内空气品质的同时减少新风能耗。     

基于压力监测医用中心压缩空气供应系统

目的：建立能够量化评价医用中心压缩空气供应系统工作状况的指标。方法：根据气体状态方程．以压力变化为监测对象进行参数计算。结果：气体用量的平均速率和瞬时速率、空气压缩机平均排气速率和启停点排气速率、空气压缩机压力-排气速率曲线等参数,可以对医用中心压缩空气供应系统进行客观评价。结论：此方法对加强设备质量管理和维护保养起到重要作用。     

燃气热水器燃烧产物中CO和NOx的产生与控制

目的研究燃气热水器燃烧产物中CO和NOx的产生与控制。方法对燃气热水器在冷态开机运行、进风口堵塞(堵塞比例为25%,50%,75%,90%)、长时间耐久燃烧(24 d耐久燃烧实验)以及不同烟道设置(0.5 m 1弯、1 m 1弯、2 m 1弯、2 m 2弯、3 m 1弯、3 m 2弯、3 m 3弯)状况下燃烧产生CO和NOx的浓度进行测定和分析。结果燃气热水器冷态开机运行时存在爆燃现象,瞬时过剩空气系数(α)为1时的CO浓度[CO(α=1)]可达约350 mg/m3,NOx浓度[NOx(α=1)]随燃烧时间的延长而增大。进风口逐渐堵塞,CO急剧上升,当堵塞到90%时,CO(α=1)浓度高达499.69 mg/m3。人工煤气为气源燃气热水器长时间耐久燃烧24 d后,CO(α=1)浓度高达494.3 mg/m3。烟道设置的长度和弯头越多,燃烧产生CO浓度越高,当烟道设置为3 m 3弯时,CO(α=1)浓度为262.7 mg/m3。结论燃气热水器开机时的爆燃、进风口堵塞、长时间耐久燃烧、烟道长度和弯头数目的增加会导致CO和NOx排放增加。用户应该正确安装、减少开机次数、定期清洁燃气热水器。     

Evaluation of a chemical factor during fires

The working conditions of firemen during active service cannot be assessed without characterizing the degree of ambient gas contamination with toxic substances. Firemen extinguish fires and liquidate accidents under difficult conditions, which presents a threat to their life and health. Fire-induced combustion products can emit as high as 100 types of chemical compounds. Of them, the most common and well-studied compounds are carbon oxide, sulfur dioxide and nitric dioxide, formaldehyde, hydrogen chloride, saturated hydrocarbons (C2-C10), acetone, benzene, toluene, and some chlorohydrocarbons (vinyl chloride, chloroform, and tetrachloromethane). These compounds are hazard classes II and III, they have been detected in the air samples in the foci of a fire in the amenity and industrial premises, during combustion of motor transport, garbage, etc. Toxicological exposure to these compounds is accelerated under elevated temperatures.     

Effects of nitrogen oxides on natural killer cells in glass craftsmen and braziers.

OBJECTIVES: To assess the effect of exposure to nitrogen oxides on peripheral blood natural killer cells. METHODS: Groups of glass craftsmen and braziers exposed to nitrogen oxides and non-exposed controls were studied. Air concentrations of nitrogen oxides were measured. Mononuclear cells isolated from peripheral blood samples were assayed for natural killer cell activity with K562 target cells in a 51Cr release assay and the percentage of natural killer cells (CD16) was measured by flow cytometry. RESULTS: Braziers were exposed to 1.2 ppm nitrogen dioxide and 8.6 ppm nitric oxide and glass craftsmen to 2.9 ppm nitrogen dioxide and 26.5 ppm nitric oxide. The natural killer cell activity of exposed workers was significantly lower than in non-exposed controls (P < 0.05 ANOVA Scheffe test). The percentage of natural killer cells in glass craftsmen was significantly greater than in controls (P < 0.05 ANOVA Scheffe test). Regression of natural killer cell activity against age, smoking habit, number of years worked and current exposure to nitrogen dioxide and nitric oxide gases was not significant. The percentage of natural killer cells was not significantly correlated with age, smoking habit, or numbers of years worked, but was significantly related to air concentrations of nitrogen dioxide (P < 0.01) and nitric oxide (P < 0.001). CONCLUSION: Natural killer cell activity and the percentage of natural killer cells in peripheral blood cells were altered in workers exposed to nitrogen oxides.     

助燃烟气对垃圾焚烧助燃空气供给的影响

给出了存在助燃烟气时垃圾焚烧炉助燃空气供给的控制公式,指出实际操作时需要考虑助燃烟气的引入对焚烧炉助燃空气的供给的影响,高含氧量助燃烟气的引入可以使助燃空气的过剩空气系数下降6%以上,兼顾余热回收与减少助燃空气供给量和垃圾焚烧烟气量,应保证助燃烟气的含氧量高于垃圾焚烧烟气的含氧量;控制公式同时包含了当量碳燃烬比对空气供给的影响.     

Developing Radiation Protection Standards

Analytical expressions for the work of breathing under conditions of laminar and turbulent flow have been derived. Helium-oxygen mixtures of greater viscosity but lower density than air, and sulfur ftexafiuoride-oxygen mixtures of greater density than air were used to test these expressions. The work of breathing was determined by measuring the oxygen consumption during quiet breathing and during hyperventilation produced by 7% carbon dioxide. Increased oxygen consumption per minute on hyperventilation with air was 55 ml, standard temperature and pressure, dry (STPD); on breathing helium-oxygen mixtures it was 57 ml STPD. Increased oxygen consumption per minute on hyperventilation with sulfur hexafluoride-oxygen mixtures was 249 ml STPD.

Increasing the viscosity of the inspired gas or decreasing its density did not significantly affect the work of breathing; a substantial increase in the density of the inspired gas lead to an increased work of breathing.     

Impact of the 2008 Beijing Olympics on the risk of pregnancy complications

Taking advantage of the natural experiment of the 2008 Beijing Olympics (August 8 to September 24), when air pollution levels decreased by 13% to 60%, the authors assessed whether having ≥1 pregnancy month during the Olympics was associated with decreased risks of hypertensive disorders (HDs) and/or fetal-placental conditions (FPCs). Singleton births to mothers with ≥1 pregnancy month in 2008 or 2009 (N = 56,155) were included. Using generalized additive models, the authors estimated the risk of HDs and FPCs associated with (1) the 2008 Olympics compared with the same dates in 2009, and (2) increased mean ambient PM₁₀ (particulate matter with an aerodynamic diameter <10 μm), NO₂ (nitrogen dioxide), and SO₂ (sulfur dioxide) concentrations during each trimester. However, no association between HDs or FPCs and having any trimester during the 2008 Olympic period was found. This may, in part, be due to a small number of pregnancy complications in this population.     

Effect of various ionizing factors on the concentration of condensation nuclei in the air of an office room

In an office room, the concentrations of condensation nuclei (CN) were measured previous to and during the action of: (1) a quartz lamp, (2) an electric heater, (3) an EDA-NW5 mechanical air moistener, and (4) a source of compressed carbon dioxide raising the CO₂ content of the air to 2%. These factors caused the following changes in CN concentrations: (1) the uv lamp, an increase of 30%; (2) the heater, an increase by 148%; (3) the CO₂ source, an increase by 42%; (4) the air humidifier, a decrease by 32%. The above variations were statistically significant (p < 0.001). Their dependence on simultaneous air ionization, their relation to the dust content of the air, and their biometeorological importance are discussed.     

Practical limitations of the Deltatrac indirect calorimeter

Indirect calorimetry is used to assess energy requirements. The Deltatrac Metabolic Monitor is a relatively inexpensive indirect calorimeter which uses a 'fixed' flow of ambient air to collect expired air. Only oxygen and carbon dioxide concentrations are measured and the 'fixed flow' is assumed in the calculation of oxygen consumption ((.)VO(2)) and carbon dioxide production ((.)VCO(2)). Using inert gas dilution we have studied the effect on (.)VO(2), and on the variability in (.)VO(2), of changing and lengthening the 1.77 m length of 35 mm tubing supplied with the instrument to collect expired air, and of using a mask to collect expired air instead of the manufacturer's hood. One would anticipate that changing the tubing could cause a change in resistance to gas flow and thus affect the true flow rate. This would alter the gas concentrations seen by the analysers, but the 'fixed flow' would still be assumed so the results would be in error. Adding extra lengths of manufacturers tubing caused an apparent rise in (.)VO(2) of 0.36%/m of tubing added, and using 22 mm tubing instead of the manufacturer's 35 mm tubing increased (.)VO(2) by 0.42% for each 10 cm of tubing added. Using the mask to collect expired air instead of the canopy (.)VO(2) was higher, possibly due to the energy cost of holding the mask, and was more variable, probably because of poorer mixing of the expired air. To measure (.)VO(2) using a mask with the same precision as a 10 min measurement made with the hood would entail measuring (.)VO(2) for 14.5 min. The methods used to collect expired air (mask or canopy, length and type of tubing) when measuring metabolic rate with the Deltatrac do affect the results obtained but these effects are small and predictable.     

Exposure assessment of non-electric ice resurfacer operators in indoor ice rinks: a pilot study

Exposure of ice resurfacer operators to indoor air contaminants was measured in six indoor ice arenas. A standardized questionnaire on technical and operational features was employed and indoor airborne concentrations of carbon monoxide (CO), carbon dioxide (CO₂), nitric oxide (NO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and total volatile organic compounds (VOCs) were measured. Air samples were collected using a range of direct reading instruments attached to the driver’s seat of the resurfacer. The range of mean exposure concentrations via positional sampling (i.e. as close as able to the operator’s breathing zone) were 5.7–7.4 ppm, 694–2171 ppm, <0.5 to 0.5 ppm, and < 0.1 to 0.2 ppm, for CO, CO₂, NO, and NO₂, respectively. Exposure levels for SO₂ and VOC were below detection. Overall, each of the measured indoor air contaminants was found to be below its respective occupational exposure limits (OEL), suggesting that the risk of hazardous exposure is low. The use of natural gas as a fuel source is believed to contribute to low contaminant concentrations.     

Validation of a new mixing chamber system for breath-by-breath indirect calorimetry

Limited validation research exists for applications of breath-by-breath systems of expired gas analysis indirect calorimetry (EGAIC) during exercise. We developed improved hardware and software for breath-by-breath indirect calorimetry (NEW) and validated this system as well as a commercial system (COM) against 2 methods: (i) mechanical ventilation with known calibration gas, and (ii) human subjects testing for 5 min each at rest and cycle ergometer exercise at 100 and 175 W. Mechanical calibration consisted of medical grade and certified calibration gas ((4.95% CO(2), 12.01% O(2), balance N(2)), room air (20.95% O(2), 0.03% CO(2), balance N(2)), and 100% nitrogen), and an air flow turbine calibrated with a 3-L calibration syringe. Ventilation was mimicked manually using complete 3-L calibration syringe manouvers at a rate of 10·min(-1) from a Douglas bag reservoir of calibration gas. The testing of human subjects was completed in a counterbalanced sequence based on 5 repeated tests of all conditions for a single subject. Rest periods of 5 and 10 min followed the 100 and 175 W conditions, respectively. COM and NEW had similar accuracy when tested with known ventilation and gas fractions. However, during human subjects testing COM significantly under-measured carbon dioxide gas fractions, over-measured oxygen gas fractions and minute ventilation, and resulted in errors to each of oxygen uptake, carbon dioxide output, and respiratory exchange ratio. These discrepant findings reveal that controlled ventilation and gas fractions are insufficient to validate breath-by-breath, and perhaps even time-averaged, systems of EGAIC. The errors of the COM system reveal the need for concern over the validity of commercial systems of EGAIC.     

Pollution of room air

In the last decade the significance of indoor air pollution to human health has increased because of improved thermal insulation of buildings to save energy: air turnover is reduced and air quality is impaired. The most frequent air pollutants are tobacco smoke, radioactive radon gas emanating from the soil, formaldehyde from furniture and insulation material, nitrogen oxides from gas stoves, as well as solvents from cleaning agents. The most important pollutants leading to health hazards are tobacco smoke and air pollutants which are emitted continuously from building materials and furniture. Such pollutants have to be eliminated by reducing the emission rate. A fresh air supply is necessary to reduce the pollutants resulting from the inhabitants and their activities, the amount depending on the number of inhabitants and the usage of the room. The carbon dioxide level should not exceed 1500 ppm.     

Absorption of 203Pb from gastrointestinal tract of man.

The influence of air pollution with dust, nitric oxides, oxidants, sulphur dioxide, formaldehyde, and phenol on the influenza epidemic 1974–1975 in Sofia has been investigated. The data collected with regard to the number of the ill, the pollution of the atmospheric air, and the meteorological conditions were subjected to a statistical analysis; a stepwise regression procedure was adopted. The results show a certain correlation between the number of the ill and the investigated pollutants and meterological factors.     

浅谈新建医院医用气体系统设计

通过复旦大学附属华山医院西院的医用气体工程实例,详细阐述了其供氧系统、负压吸引系统、压缩空气系统、气体报警系统的设计,为新建医院进行医用气体系统设计提供参考。     

The Case of the Coughing Duck Hunter

The relationship between average and peak personal exposure to nitrogen dioxide and urinary excretion of hydroxyproline and desmosine was investigated in a population of preschool children and their mothers. Weekly average personal nitrogen dioxide exposures for subjects who resided in homes with one or more potential nitrogen dioxide source (e.g., a kerosene space heater, gas stove, or tobacco smoke) ranged between 16.3 and 50.6 ppb (30.6 and 95.1 μg/m³) for children and between 16.9 and 44.1 ppb (12.8 and 82.9 μg/m³) for mothers. In these individuals, the hydroxyproline-to-creatinine and desmosine-to-creatinine ratios were unrelated to personal nitrogen dioxide exposure—even though continuous monitoring documented home nitrogen dioxide concentration peaks of 100–475 ppb lasting up to 100 h in duration. Significantly higher hydroxyproline-to-creatinine and desmosine-to-creatinine ratios were observed in children, compared with mothers (p < .001 and .003, respectively).     

Mutagenic activity of ultraviolet-irradiated mixtures of nitrogen dioxide and propene or butadiene

The mutagenic activities of mixtures of nitrogen dioxide and 1,3-butadiene or propene were investigated after uv-irradiation in a small, laboratory-bench scale flow-through gas exposure system. The tester organism was Salmonella typhimurium, principally strain TA100. The photoreaction products from 1,3-butadiene and nitrogen dioxide were more mutagenic than those from propene and nitrogen dioxide. Approximately 0.25 ppm butadiene, compared to 100 ppm propene, was needed to give a significant mutagenic effect with 0.25 ppm NO2 after 6 hr exposure. The influence of different experimental conditions on mutagenic activity was studied using propene plus nitrogen dioxide. Increasing the mean reaction time from 40 min to 1 hr 20 min or 3 hr 20 min by reduction of the flow rate through the 20-liter reaction vessel did not appreciably increase the sensitivity of the system, nor did humidification of the air, omission of the metabolic system (S9 mix), or spreading of the bacteria on the agar surface. Prolongation of the exposure time from 6 to 16 or 24 hr did, however, give an increased mutagenic response. With prolonged exposure, a slight mutagenic effect could also be detected with ethene + NO2 + uv. Ozone addition did not appreciably enhance the mutagenic response.