Hydraulic fluids and jet engine oil: pyrolysis and aircraft air quality

Incidents of smoke in aircraft cabins often result from jet engine oil and/or hydraulic fluid that leaks into ventilation air, which can be subjected to temperatures that exceed 500 degrees C. Exposed flight-crew members have reported symptoms, including dizziness, nausea, disorientation, blurred vision, and tingling in the legs and arms. In this study, the authors investigated pyrolysis products of one jet engine oil and two hydraulic fluids at 525 degrees C. Engine oil was an important source of carbon monoxide. Volatile agents and organophosphate constituents were released from all the agents tested; however, the neurotoxin trimethyl propane phosphate was not found. The authors hypothesized that localized condensation of pyrolysis products in ventilation ducts, followed by mobilization when cabin heat demand was high, accounted for mid-flight incidents. The authors recommended that carbon monoxide data be logged continuously to capture levels during future incidents.     

Hydraulic Fluids and Jet Engine Oil: Pyrolysis and Aircraft Air Quality

Incidents of smoke in aircraft cabins often result from jet engine oil and/or hydraulic fluid that leaks into ventilation air, which can be subjected to temperatures that exceed 500 °C. Exposed flight-crew members have reported symptoms, including dizziness, nausea, disorientation, blurred vision, and tingling in the legs and arms. In this study, the authors investigated pyrolysis products of one jet engine oil and two hydraulic fluids at 525 °C. Engine oil was an important source of carbon monoxide. Volatile agents and organophosphate constituents were released from all the agents tested; however, the neurotoxin trimethyl propane phosphate was not found. The authors hypothesized that localized condensation of pyrolysis products in ventilation ducts, followed by mobilization when cabin heat demand was high, accounted for mid-flight incidents. The authors recommended that carbon monoxide data be logged continuously to capture levels during future incidents.     

The toxicity of commercial jet oils

Jet oils are specialized synthetic oils used in high-performance jet engines. They have an appreciable hazard due to toxic ingredients, but are safe in use provided that maintenance personnel follow appropriate safety precautions and the oil stays in the engine. Aircraft engines that leak oil may expose others to the oils through uncontrolled exposure. Airplanes that use engines as a source of bleed air for cabin pressurization may have this source contaminated by the oil if an engine leaks. Examination of the ingredients of the oil indicates that at least two ingredients are hazardous: N-phenyl-1-naphthylamine (a skin sensitizer) and tricresyl phosphate (a neurotoxicant, if ortho-cresyl isomers are present). Publicly available information such as labels and MSDS understates the hazards of such ingredients and in the case of ortho-cresyl phosphates by several orders of magnitude.     

Determination of tricresyl phosphate air contamination in aircraft

Monitoring of tricresyl phosphate (TCP) contamination of cockpit air was undertaken in three types of military aircraft [fighter trainer (FT), fighter bomber (FB), and cargo transport (CT) aircraft]. The aircraft had a previous history of pilot complaints about cockpit air contamination suspected to originate from the engine bleed air supply through the entry of aircraft turbine engine oil (ATO) into the engine compressor. Air samples were collected in flight and on the ground during engine runs using sorbent tubes packed with Porapak Q and cellulose filters. A total of 78 air samples were analysed, from 46 different aircraft, and 48 samples were found to be below the limit of detection. Nine incidents of smoke/odour were identified during the study. The concentrations of toxic o-cresyl phosphate isomers were below the level of detection in all samples. The highest total TCP concentration was 51.3 μg m(-3), while most were generally found to be <5 μg m(-3) compared with the 8-h time-weighted average exposure limit of 100 μg m(-3) for tri-o-cresyl phosphate. The highest concentrations were found at high engine power. Although TCP contamination of cabin/cockpit air has been the subject of much concern in aviation, quantitative data are sparse.     

Fluid dynamic analysis of pollutants’ dispersion behind an aircraft engine during idling

The potential impact of emissions from airports on human health and air quality has become a significant issue. The aim of this paper is to investigate the dispersion behind an aircraft engine during idle-engine operations at airports. When these operations are conducted on the apron, jet engine emissions worsen the air quality where ground handling personnel works and passengers embark or disembark. Ground operations at airports are designed according to the International Civil Aviation Organization jet blast definition that indicates the exhaust gas velocity of 56 km/h as the threshold limit for the comfort of operations behind an aircraft, without considering the pollutants’ dispersion and concentration levels. In this paper, carbon monoxide (CO), formaldehyde (CH₂O), and acrolein (C₃H₄O) dispersion behind a twin engine jet aircraft during idling is investigated using a computational fluid dynamic tool. The complete geometry of a Boeing 737-500 is used as reference. The steady-state simulation of turbulent jet flow is carried out using a realizable k???ε model. Three different scenarios are investigated at standard day conditions—101,325 Pa and 288 K, with no wind, and the plume concentrations are presented and discussed. CO, CH₂O, and C₃H₄O concentration curves are drawn and compared with the exposure threshold limit defined by scientific international communities to guarantee human health. The information provided from this study represents a first step in understanding apron air quality issues during idle-engine operations.     

民用飞机客舱空气质量标准限值及检测方法的比较

目的为飞机客舱空气质量污染事故调查、飞机适航认证及客舱环境卫生监测提供参考。方法比较目前国内外民用飞机客舱空气质量标准限值及检测方法。结果我国民用飞机客舱空气质量参数限值与国外限值要求有一定差别,主要是我国飞机客舱相对湿度限值比国外限值要求偏高;我国客舱温度限值要求按季节划分,国外则按飞机地面和巡航状态区分;我国客舱风速的限值略大于国外限值;而我国客舱二氧化碳和一氧化碳浓度限值均小于国外限值。其部分相关的检测方法也与国外存在一定差距。结论我国公共交通工具卫生标准中有关飞机客舱卫生部分参数限值及检测方法尚不够合理,建议应建立适合我国飞机客舱空气质量的卫生标准体系,包括飞机客舱空气质量各参数限值及其检测方法、评价指南等。     

The influence of ozone on self-evaluation of symptoms in a simulated aircraft cabin

Simulated 4-h flights were carried out in a realistic model of a three-row, 21-seat section of an aircraft cabin that was reconstructed inside a climate chamber. Twenty-nine female subjects, age 19-27 years, were split into two groups; each group was exposed to four conditions: two levels of ozone (<2 and 60-80 p.p.b.) at two outside air supply rates (2.4 and 4.7 l/s per person). A companion study measured the chemicals present in the cabin air during each of the simulated flights. The subjects completed questionnaires to provide subjective assessments of air quality and symptoms typical of complaints experienced during actual flight. Additionally, the subjects' visual acuity, nasal peak flow and skin dryness were measured. Based on self-recorded responses after 3(1/4) h in the simulated aircraft cabin, they judged the air quality and 12 of the symptoms (including eye and nasal irritation, lip and skin dryness, headache, dizziness, mental tension, claustrophobia) to be significantly worse (P<0.05) for the "ozone" condition compared to the "no ozone" condition. The results indicate that ozone and products of ozone-initiated chemistry are contributing to such complaints, and imply previously unappreciated benefits when ozone is removed from the ventilation air supplied to an aircraft cabin.     

Trends in cabin air quality of commercial aircraft: industry and passenger perspectives

The small air space available per person in a fully occupied aircraft passenger cabin accentuates the human bioeffluent factor in the maintenance of air quality. The accumulation of carbon dioxide and other contributions to poor air quality that can occur with inadequate ventilation, even under normal circumstances, is related to the volume of available air space per person and various ventilation rates. This information is compared with established air quality guidelines to make specific recommendations with reference to aircraft passenger cabins under both normal and abnormal operating conditions. The effects of respiration on the air quality of any enclosed space from the respiration of a resting adult are estimated using standard equations. Results are given for different volumes of space per person, for zero air exchange, and for various air change rates. The required ventilation rates estimated in this way compared closely with results calculated using a standard empirical formula. The results confirm that the outside air ventilation required to achieve a target carbon dioxide concentration in the air of an occupied enclosed space remains the same regardless of the volume of that space. The outside air ventilation capability of older and more recent aircraft is then reviewed and compared with the actual measurements of cabin air quality for these periods. The correlation between calculated and measured aircraft cabin carbon dioxide concentrations from other studies was very good. Respiratory benefits and costs of returning to the 30% higher outside air ventilation rates and 8% higher cabin pressures of the 1960s and 1970s are outlined. Consideration is given to the occasional occurrence of certain types of aircraft malfunction that can introduce more serious contaminants to the aircraft cabin. Recommendations and suggestions for aircraft builders and operators are made that will help improve aircraft cabin air quality and the partial pressure of oxygen that is available to passengers at minimal cost. Also suggested are some measures that passengers can take to help improve their comfort and decrease their risk of illness, particularly on long-haul flights.     

Combustion of diesel fuel from a toxicological perspective

Summary Since the use of diesel engines is still increasing, the contribution of their incomplete combustion products to air pollution is becoming ever more important. The presence of irritating and genotoxic substances in both the gas phase and the particulate phase constituents is considered to have significant health implications. The quantity of soot particles and the particle-associated organics emitted from the tail pipe of a diesel-powered vehicle depend primarily on the engine type and combustion conditions but also on fuel properties. The quantity of soot particles in the emissions is determined by the balance between the rate of formation and subsequent oxidation. Organics are adsorbed onto carbon cores in the cylinder, in the exhaust system, in the atmosphere and even on the filter during sample collection. Diesel fuel contains polycyclic aromatic hydrocarbons (PAHs) and some alkyl derivatives. Both groups of compounds may survive the combustion process. PAHs are formed by the combustion of crankcase oil or may be resuspended from engine and/or exhaust deposits. The conversion of parent PAHs to oxygenated and nitrated PAHs in the combustion chamber or in the exhaust system is related to the vast amount of excess combustion air that is supplied to the engine and the high combustion temperature. Whether the occurrence of these derivatives is characteristic for the composition of diesel engine exhaust remains to be ascertained. After the emission of the particles, their properties may change because of atmospheric processes such as aging and resuspension. The particle-associated organics may also be subject to (photo)chemical conversions or the components may change during sampling and analysis. Measurement of emissions of incomplete combustion products as determined on a chassis dynamometer provides knowledge of the chemical composition of the particle-associated organics. This knowledge is useful as a basis for a toxicological evaluation of the health hazards of diesel engine emissions.     

Increased urinary excretion of 8-hydroxydeoxyguanosine in engine room personnel exposed to polycyclic aromatic hydrocarbons

Background: Previous investigations indicate that engine room personnel on ships are exposed to polycyclic aromatic hydrocarbons (PAH) from oil and oil products, with dermal uptake as the major route of exposure. Several PAH are known carcinogens and mutagens.

Aims: To investigate the urinary excretion of a marker for oxidative DNA damage, 8-hydroxydeoxy-guanosine (8OHdG), in engine room personnel, and to study the association between 8OHdG and 1-hydroxypyrene (1OHP), a biological marker for PAH exposure.

Methods: Urine samples were collected from engine room personnel (n = 36) on 10 Swedish and Norwegian ships and from unexposed controls (n = 34) with similar age and smoking habits. The exposure to oils, engine exhaust, and tobacco smoke 24 hours prior to sampling was estimated from questionnaires. The urinary samples were frozen for later analyses of 8OHdG and 1OHP by high performance liquid chromatography.

Results: Excretion in urine of 8OHdG (adjusted to density 1.022) was similar for controls (mean 18.0 nmol/l, n = 33), and for those who had been in the engine room without skin contact with oils (mean 18.7 nmol/l, n = 15). Engine room personnel who reported skin contact with oil had increased excretion of 8OHdG (mean 23.2 nmol/l, n = 19). The difference between this group and the unexposed controls was significant. The urinary levels of ln 1OHP and ln 8OHdG were significantly correlated, and the association was still highly significant when the effects of smoking and age were accounted for in a multiple regression analysis.

Conclusion: Results indicate that exposure to PAH or possibly other compounds from skin contact with oils in engine rooms may cause oxidative DNA damage.

     

Airliner cabin air quality

Airliner cabin air quality has attracted a lot of attention in the last two decades and has generated much controversy. This article reviews the situation to date only as it pertains to cabin air quality during normal aircraft operation. First discussed are the basic assumptions from the early days of commercial aviation. Second, different factors involved in cabin air quality are reviewed in some detail. Evidence from the current literature is employed to demonstrate that airliner cabin air quality is adequate and does not compromise aircrew health. However, the author does recognize that further studies are required for additional clarification of the issue.     

家用燃料气态燃烧产物对室内空气污染的初步评估

目的 初步评估天然气、液化石油气和蜂窝煤的气态燃烧产物对室内空气污染的影响程度和特征.方法 在特别设计的3间实验房间内分别使用天然气、液化石油气和蜂窝煤在室内进行定量燃烧,同时根据国家标准方法采集空气样品并测定SO2、NO2、CO和甲醛的浓度,对其排放量和排放特征进行分析.结果 3种燃料的气态燃烧产物(SO2、NO2、CO、甲醛)中,均以CO和NO2的排放量最高.在日均用量下,蜂窝煤的CO和NO2排放量远高于天然气和液化石油气.使用蜂窝煤的家庭CO单位排放量高达30 136 mg/kg,明显高于液化石油气(8 725 mg/kg)和天然气(2 755 mg/kg);液化石油气的NO2单位排放量(42.69 mg/kg)则明显高于蜂窝煤(20.01 mg/kg)和天然气(11.87 mg/m3).在通风不良的室内,均可使室内CO和NO2浓度均超过GB/T 18883-2002<室内空气质量标准>.结论 厨房室内燃烧天然气或液化石油气,能造成CO和NO2的污染.     

Dichlorvos vapour disinsection of aircraft

The authors describe the testing of an automatic aircraft disinsection system permanently installed on a commercial DC-6B passenger aircraft. An air-compressor forces ambient cabin air, partially saturated with dichlorvos vapour at a set concentration, through the cabin, cockpit and baggage compartments of the aircraft for 30 minutes. Insecticide concentrations and insect mortality were observed in post-overhaul check flights, and insect mortality and passenger reactions were observed on scheduled flights between Miami, Florida, and Nassau, Bahamas.     

Fractionation of synthetic crude oils from coal for biological testing

A separations procedure that has been used extensively for the reproducible fractionation of cigarette smoke condensate in order to test this material systematically for its carcinogenic properties has been applied to coal liquefaction products. Two types of product oils, one a light oil and the other a heavy tar, have been processed successfully by this procedure. Reproducibility was similar to that reported for condensate fractionations. Proportions, by weight, of fourteen major fractions and some subfractions of the two products were determined. Mutagenicity of the major fractions of the light oil product was tested by microbiological techniques using several strains of Salmonella typhimurium and some mutagenic effect was shown by four of the fractions. The possible carcinogenicity and mutagenicity of the individual fractions are discussed in relation to the reported effects of corresponding cigarette smoke condensate fractions.     

Formation and analysis of carbon monoxide in cigarette mainstream and sidestream smoke.

Carbon monoxide is one of the three cigarette smoke constituents which have been judged as “most likely to contribute to the health hazards of smoking.” CO is formed in the burning cigarette by oxidation of nonvolatile carbonaceous matter, by reduction of CO₂, and by pyrolysis of nonvolatile organic matter, primarily cellulose and cellulose-like materials. The best currently known way to control the CO formation in the burning cigarette is air dilution by porous cigarette paper or by perforated filter tips. During the smoldering of a cigarette between puffs about 2.5 times more CO is formed than during actual smoking. The release of CO in sidestream smoke from tobacco products has on occasion led to short-term occurrence of up to 50 ppm of CO in enclosed environments.     

Airborne contaminants during controlled residential fires

In this study, we characterize the area and personal air concentrations of combustion byproducts produced during controlled residential fires with furnishings common in 21^st century single family structures. Area air measurements were collected from the structure during active fire and overhaul (post suppression) and on the fireground where personnel were operating without any respiratory protection. Personal air measurements were collected from firefighters assigned to fire attack, victim search, overhaul, outside ventilation, and command/pump operator positions. Two different fire attack tactics were conducted for the fires (6 interior and 6 transitional) and exposures were compared between the tactics. For each of the 12 fires, firefighters were paired up to conduct each job assignment, except for overhaul that was conducted by 4 firefighters. Sampled compounds included polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs, e.g., benzene), hydrogen cyanide (HCN), and particulate (area air sampling only). Median personal air concentrations for the attack and search firefighters were generally well above applicable short-term occupational exposure limits, with the exception of HCN measured from search firefighters. Area air concentrations of all measured compounds decreased after suppression. Personal air concentrations of total PAHs and benzene measured from some overhaul firefighters exceeded exposure limits. Median personal air concentrations of HCN (16,300 ppb) exceeded the exposure limit for outside vent firefighters, with maximum levels (72,900 ppb) higher than the immediately dangerous to life and health (IDLH) level. Median air concentrations on the fireground (including particle count) were above background levels and highest when collected downwind of the structure and when ground-level smoke was the heaviest. No statistically significant differences in personal air concentrations were found between the 2 attack tactics. The results underscore the importance of wearing self-contained breathing apparatus when conducting overhaul or outside ventilation activities. Firefighters should also try to establish command upwind of the structure fire, and if this cannot be done, respiratory protection should be considered.     

两种类型蚊香烟雾对室内空气污染的研究

目的：了解有烟蚊香和无烟蚊香烟雾对室内空气的污染状况。方法：对有烟蚊香和无烟蚊香在不同通风状态、不同燃烧时间下室内一氧化碳(CO)、二氧化碳(CO2)、可吸入颗粒物(IP)及二氧化氮(NO2)浓度进行测定。结果：在门窗关闭状态下：有烟蚊香燃烧后室内CO、CO2和IP浓度均有超标现象，无烟蚊香燃烧后室内CO浓度严重超标，室内CO2浓度在个别时间点亦出现超标。在门窗全开状态下：有烟蚊香燃烧后IP浓度出现超标，其余指标均未超标，无烟蚊香燃烧后各指标均未超标。两种蚊香烟雾无NO2污染。结论：有烟蚊香和无烟蚊香烟雾都能造成严重的室内空气污染。有烟蚊香主要造成室内IP严重污染，无烟蚊香主要造成室内CO严重污染。开窗通风能有效降低蚊香烟雾造成的室内空气污染物浓度。     

Does switching from cigarettes to pipes or cigars reduce tobacco smoke exposure?

Cigarette smoking histories, reported depth of inhalation, number of pipe and cigars (PC) smoked, serum thiocyanate (SCN) and expired air carbon monoxide (CO) levels were examined in PC male smokers enrolled in the Multiple Risk Factor Intervention Trial (MRFIT). Serum SCN levels for all PC smokers were higher than for non-smokers and lower than for current cigarette smokers. Levels were related to the amount of product smoke. Prior cigarette smokers had higher SCN levels when compared to PC users who had never smoked cigarettes, smoked a larger number of tobacco products per day, and reported inhaling into the chest more often. Prospective data on baseline cigarette smokers demonstrated that smokers who stopped all tobacco products had a greater drop in SCN and CO than those who switched to PC. The findings strongly suggest that cessation of all tobacco products is the best strategy for decreasing exposure to tobacco smoke.     

The nature of air pollution and the methods available for measuring it

At present the principal sources of energy in Europe are coal and oil and fuels derived from them, and in European towns air pollution consists mainly of their combustion products. These combustion products naturally divide into two categories, gaseous and particulate, which are very different chemically and which behave very differently when they are near collecting surfaces; they therefore require very different techniques both for collecting and for estimating samples. Some methods of measurement, suitable for everyday routine use in Europe, are described; these offer a compromise between completeness and economy, and can help to give a general outline of the air pollution situation without undue complexity or prohibitive cost.