Prevention of mosquitoes (Diptera: Culicidae) and house flies (Diptera: Muscidae) from entering simulated aircraft with commercial air curtain units

Commercially available air curtain units were used to create air barriers to prevent mosquitoes and house flies from entering a simulated aircraft doorway together with passengers. Two assemblies of simulated passenger bridge and aircraft were constructed, and airflow measurements were recorded to confirm airflow characteristics for several combinations of commercial units. Three mosquito species were selected for different host-seeking characteristics, and house flies were selected to represent a large, strong-flying insect. Batches of 20 or 200 insects of four species were released into the passenger bridge just before 25 persons passed through the assembly, then insects that entered the aircraft cabin were recovered. Results showed that horizontal plus vertical or vertical-mounted air curtain units with the airflow directed at a 45 degrees angle into the passenger bridge excluded 95-99% of the mosquitoes and 95-100% of the house flies, respectively. Airflows were measured and estimated to be effective if the mean was > 4 m/s in the critical area in the center of the converging airflows. The study validates the concept that air barriers can effectively prevent the passage of flying insects into an aircraft.     

An analysis on the detection of biological contaminants aboard aircraft

The spread of infectious disease via commercial airliner travel is a significant and realistic threat. To shed some light on the feasibility of detecting airborne pathogens, a sensor integration study has been conducted and computational investigations of contaminant transport in an aircraft cabin have been performed. Our study took into consideration sensor sensitivity as well as the time-to-answer, size, weight and the power of best available commercial off-the-shelf (COTS) devices. We conducted computational fluid dynamics simulations to investigate three types of scenarios: (1) nominal breathing (up to 20 breaths per minute) and coughing (20 times per hour); (2) nominal breathing and sneezing (4 times per hour); and (3) nominal breathing only. Each scenario was implemented with one or seven infectious passengers expelling air and sneezes or coughs at the stated frequencies. Scenario 2 was implemented with two additional cases in which one infectious passenger expelled 20 and 50 sneezes per hour, respectively. All computations were based on 90 minutes of sampling using specifications from a COTS aerosol collector and biosensor. Only biosensors that could provide an answer in under 20 minutes without any manual preparation steps were included. The principal finding was that the steady-state bacteria concentrations in aircraft would be high enough to be detected in the case where seven infectious passengers are exhaling under scenarios 1 and 2 and where one infectious passenger is actively exhaling in scenario 2. Breathing alone failed to generate sufficient bacterial particles for detection, and none of the scenarios generated sufficient viral particles for detection to be feasible. These results suggest that more sensitive sensors than the COTS devices currently available and/or sampling of individual passengers would be needed for the detection of bacteria and viruses in aircraft.     

The Sickle-cell and Altitude

High altitude seemed to be responsible for seven recent cases of sickling crisis. People with sickle-cell trait are at risk if they fly in unpressurized aircraft, which are used for many local air services. Those with sickle-cell haemoglobin C disease should avoid air travel even in pressurized aircraft. Possibly as a result of “autosplenectomy,” patients with sickle-cell anaemia seem to be able to fly in pressurized aircraft with little risk. All passengers and aircrew who might have some form of sickle-cell disease should be screened before flight.     

Self-organization leads to supraoptimal performance in public transportation systems

The performance of public transportation systems affects a large part of the population. Current theory assumes that passengers are served optimally when vehicles arrive at stations with regular intervals. In this paper, it is shown that self-organization can improve the performance of public transportation systems beyond the theoretical optimum by responding adaptively to local conditions. This is possible because of a "slower-is-faster" effect, where passengers wait more time at stations but total travel times are reduced. The proposed self-organizing method uses "antipheromones" to regulate headways, which are inspired by the stigmergy (communication via environment) of some ant colonies.     

Human mobility networks, travel restrictions, and the global spread of 2009 H1N1 pandemic

After the emergence of the H1N1 influenza in 2009, some countries responded with travel-related controls during the early stage of the outbreak in an attempt to contain or slow down its international spread. These controls along with self-imposed travel limitations contributed to a decline of about 40% in international air traffic to/from Mexico following the international alert. However, no containment was achieved by such restrictions and the virus was able to reach pandemic proportions in a short time. When gauging the value and efficacy of mobility and travel restrictions it is crucial to rely on epidemic models that integrate the wide range of features characterizing human mobility and the many options available to public health organizations for responding to a pandemic. Here we present a comprehensive computational and theoretical study of the role of travel restrictions in halting and delaying pandemics by using a model that explicitly integrates air travel and short-range mobility data with high-resolution demographic data across the world and that is validated by the accumulation of data from the 2009 H1N1 pandemic. We explore alternative scenarios for the 2009 H1N1 pandemic by assessing the potential impact of mobility restrictions that vary with respect to their magnitude and their position in the pandemic timeline. We provide a quantitative discussion of the delay obtained by different mobility restrictions and the likelihood of containing outbreaks of infectious diseases at their source, confirming the limited value and feasibility of international travel restrictions. These results are rationalized in the theoretical framework characterizing the invasion dynamics of the epidemics at the metapopulation level.     

Passenger thermal perceptions, thermal comfort requirements, and adaptations in short- and long-haul vehicles

While thermal comfort in mass transportation vehicles is relevant to service quality and energy consumption, benchmarks for such comfort that reflect the thermal adaptations of passengers are currently lacking. This study reports a field experiment involving simultaneous physical measurements and a questionnaire survey, collecting data from 2,129 respondents, that evaluated thermal comfort in short- and long-haul buses and trains. Experimental results indicate that high air temperature, strong solar radiation, and low air movement explain why passengers feel thermally uncomfortable. The overall insulation of clothing worn by passengers and thermal adaptive behaviour in vehicles differ from those in their living and working spaces. Passengers in short-haul vehicles habitually adjust the air outlets to increase thermal comfort, while passengers in long-haul vehicles prefer to draw the drapes to reduce discomfort from extended exposure to solar radiation. The neutral temperatures for short- and long-haul vehicles are 26.2°C and 27.4°C, while the comfort zones are 22.4–28.9°C and 22.4–30.1°C, respectively. The results of this study provide a valuable reference for practitioners involved in determining the adequate control and management of in-vehicle thermal environments, as well as facilitating design of buses and trains, ultimately contributing to efforts to achieve a balance between the thermal comfort satisfaction of passengers and energy conserving measures for air-conditioning in mass transportation vehicles.     

Helping patients travel by air.

Although safe and rapid, air travel may present problems for people with certain medical conditions. Most medical emergencies that occur during a flight are preventable by judicious screening and preparation. We provide guidelines for physicians who are consulted about the wisdom of undertaking a journey by air. Potential stresses before, during and after the flight are outlined, including decreased atmospheric pressure, low humidity, turbulence, inactivity and time changes. We recommend precautionary measures for passengers with certain medical conditions, such as recent myocardial infarction, pulmonary disorders, pneumothorax, cerebrovascular accidents and diabetes and for those who have recently had surgery. The policy regarding air travel for pregnant women varies with each airline, but for certain conditions associated with pregnancy supplemental oxygen should be ordered before the trip. The special equipment and care that most airlines offer to ill or disabled people are described.     

My Sentence Is Over But Will My Punishment Ever End

While America has increasingly become known for having a higher rate of persons in prison or under correctional supervision than any other country in the world; over the last two decades, new laws have begun emerging in America, placing restrictions on former offenders long after their correctional supervision has ended. These laws directly impact the lives of millions of ex-offenders who are no longer under correctional supervision, placing restrictions on where they may live, work and travel. The following essay, by a former offender who discharged parole in December 2000, highlights the punitive and destructive nature of these laws.     

Detection of respiratory viruses on air filters from aircraft

Aims: To evaluate the feasibility of identifying viruses from aircraft cabin air, we evaluated whether respiratory viruses trapped by commercial aircraft air filters can be extracted and detected using a multiplex PCR, bead‐based assay. Methods and Results: The ResPlex II assay was first tested for its ability to detect inactivated viruses applied to new filter material; all 18 applications of virus at a high concentration were detected. The ResPlex II assay was then used to test for 18 respiratory viruses on 48 used air filter samples from commercial aircraft. Three samples tested positive for viruses, and three viruses were detected: rhinovirus, influenza A and influenza B. For 33 of 48 samples, internal PCR controls performed suboptimally, suggesting sample matrix effect. Conclusion: In some cases, influenza and rhinovirus RNA can be detected on aircraft air filters, even more than 10 days after the filters were removed from aircraft. Significance and Impact of the Study: With protocol modifications to overcome PCR inhibition, air filter sampling and the ResPlex II assay could be used to characterize viruses in aircraft cabin air. Information about viruses in aircraft could support public health measures to reduce disease transmission within aircraft and between cities.     

The model of response to viral haemorrhagic fevers of the National Institute for Infectious Diseases "Lazzaro Spallanzani".

Viral haemorrhagic fevers (VHF) are severe and life-threatening diseases caused by a range of viruses. However, only four agents of VHF are known to be readily capable of person-to-person spread: Lassa virus, Crimean/Congo haemorrhagic fever virus, Ebola and Marburg viruses. Diseases caused by these viruses are endemic only in few areas in the world, most notably Africa and some rural parts of the Middle East and Eastern Europe. Nonetheless, the increasing volume of international travel presents a greater likelihood for the importation of these infections or of suspected cases in non endemic countries. Four conditions can lead to the importation and to the subsequent recognition of VHF within Europe: 1) patients arriving as a result of a planned medical evacuation; 2) persons who became sick on route to their destination; 3) persons discovered ill when entering a country, for example during routine clinical examination at the airport; 4) persons becoming sick after their arrival. Public health implications and the risk of secondary spread of pathogens in the above reported circumstances are very different. Similarly, preparedness and response should vary. This paper summarizes the present knowledge on the four VHF capable of person-to-person spread, describes the high isolation area constructed at the Italian National Institute for Infectious Diseases Lazzaro Spallanzani in Rome to respond to the occurrence of VHF. A brief overview of procedures and equipment adopted is provided.     

Emergency transport by aeromedical blimp.

Recently there has been an explosive growth in the use of helicopters and fixed wing aircraft for the transportation of patients who are ill and injured. Although using such methods of transport may result in faster access to health care centres, their ultimate role for the civilian population is unclear. Unfortunately, there are many problems associated with aeromedical transport, particularly with rotary wing aircraft, which have shown an alarming tendency to crash. The use of lighter than air vehicles (blimps, hot air balloons) might offer most of the advantages of conventional aieromedical transport, with an appreciable improvement in safety.     

Impact of Cabin Ozone Concentrations on Passenger Reported Symptoms in Commercial Aircraft

Due to elevated ozone concentrations at high altitudes, the adverse effect of ozone on air quality, human perception and health may be more pronounced in aircraft cabins. The association between ozone and passenger-reported symptoms has not been investigated under real conditions since smoking was banned on aircraft and ozone converters became more common. Indoor environmental parameters were measured at cruising altitude on 83 US domestic and international flights. Passengers completed a questionnaire about symptoms and satisfaction with the indoor air quality. Average ozone concentrations were relatively low (median: 9.5 ppb). On thirteen flights (16%) ozone levels exceeded 60 ppb, while the highest peak level reached 256 ppb for a single flight. The most commonly reported symptoms were dry mouth or lips (26%), dry eyes (22.1%) and nasal stuffiness (18.9%). 46% of passengers reported at least one symptom related to the eyes or mouth. A third of the passengers reported at least one upper respiratory symptom. Using multivariate logistic (individual symptoms) and linear (aggregated continuous symptom variables) regression, ozone was consistently associated with symptoms related to the eyes and certain upper respiratory endpoints. A concentration-response relationship was observed for nasal stuffiness and eye and upper respiratory symptom indicators. Average ozone levels, as opposed to peak concentrations, exhibited slightly weaker associations. Medium and long duration flights were significantly associated with more symptoms compared to short flights. The relationship between ultrafine particles and ozone on flights without meal service was indicative of ozone-initiated chemistry.     

An estimation of Canadian population exposure to cosmic rays from air travel

Based on air travel statistics in 1984, it was estimated that less than 4 % of the population dose from cosmic ray exposure would result from air travel. In the present study, cosmic ray doses were calculated for more than 3,000 flights departing from more than 200 Canadian airports using actual flight profiles. Based on currently available air travel statistics, the annual per capita effective dose from air transportation is estimated to be 32 μSv for Canadians, about 10 % of the average cosmic ray dose received at ground level (310 μSv per year).     

First jet lag symptoms after travelling across multiple time zones

Jet lag is a consequence of desynchronisation of human endogenous circadian rhythm with respect to the immediate environment. The slower adaptation rate of the internal rhythm in contrast to rapid travel in commercial aircraft results in symptoms such as insomnia or daytime fatigue. A group of 53 travelling subjects answered the Charité Jet Lag Scale (CJLS) questionnaire, the first of its kind in German. The CJLS represents a holistic approach to the individual symptoms of jet lag. Study results indicate a possible enhancement by shortening the CJLS to a morning and evening report. Moreover, our study determined a decreasing exponential gradient for jet lag during the first days after travel. Physical and mental symptoms are identified as the primary predictors of jet lag. The CJLS and its future translations could lead to a consistent interviewing method – one key factor for development of future intervention methods to manage jet lag.     

Life Cycle Assessment of Kerosene Used in Aviation (8 pp)

Goal, Scope, and Background The main goal of the study is a comprehensive life cycle assessment of kerosene produced in a refinery located in Thessaloniki (Greece) and used in a commercial jet aircraft. Methods The Eco-Indicator 95 weighting method is used for the purpose of this study. The Eco-Indicator is a method of aggregation (or, as described in ISO draft 14042, 'weighting through categories') that leads to a single score. In the Eco-indicator method, the weighing factor (We) applied to an environmental impact index (greenhouse effect, ozone depletion, etc.) stems from the 'main' damage caused by this environmental impact. Results and Discussion The dominant source of greenhouse gas emissions is from kerosene combustion in aircraft turbines during air transportation, which contributes 99.5% of the total CO2 emissions. The extraction and refinery process of crude oil contribute by around 0.22% to the GWP. This is a logical outcome considering that these processes are very energy intensive. Transportation of crude oil and kerosene have little or no contribution to this impact category. The main source of CFC-11 equivalent emissions is refining of crude oil. These emissions derive from emissions that result from electricity production that is used during the operation of the refinery. NOx emissions contribute the most to the acidification followed by SO2 emissions. The main source is the use process in a commercial jet aircraft, which contributes approximately 96.04% to the total equivalent emissions. The refinery process of crude oil contributes by 2.11% mainly by producing SO2 emissions. This is due to the relative high content of sulphur in the input flows of these processes (crude oil) that results to the production of large amount of SO2. Transportation of crude oil by sea (0.76%) produces large amount of SO2 and NOx due to combustion of low quality liquid fuels (heavy fuel oil). High air emissions of NOx during kerosene combustion result in the high contribution of this subsystem to the eutrophication effect. Also, water emissions with high nitrous content during the refining and extraction of crude oil process have a big impact to the water eutrophication impact category. Conclusion The major environmental impact from the life cycle of kerosene is the acidification effect, followed by the greenhouse effect. The summer smog and eutrophication effect have much less severe effect. The main contributor is the combustion of kerosene to a commercial jet aircraft. Excluding the use phase, the refining process appears to be the most polluting process during kerosene's life cycle. This is due to the fact that the refining process is a very complicated energy intensive process that produces large amounts and variety of pollutant substances. Extraction and transportation of crude oil and kerosene equally contribute to the environmental impacts of the kerosene cycle, but at much lower level than the refining process. Recommendation and Perspective The study indicates a need for a more detailed analysis of the refining process which has a very high contribution to the total equivalent emissions of the acidification effect and to the total impact score of the system (excluding the combustion of kerosene). This is due to the relative high content of sulphur in the input flows of these processes (crude oil) that results to the production of large amount of SO2.     

A Global Airport-Based Risk Model for the Spread of Dengue Infection via the Air Transport Network

The number of travel-acquired dengue infections has seen a consistent global rise over the past decade. An increased volume of international passenger air traffic originating from regions with endemic dengue has contributed to a rise in the number of dengue cases in both areas of endemicity and elsewhere. This paper reports results from a network-based risk assessment model which uses international passenger travel volumes, travel routes, travel distances, regional populations, and predictive species distribution models (for the two vector species, Aedes aegypti and Aedes albopictus) to quantify the relative risk posed by each airport in importing passengers with travel-acquired dengue infections. Two risk attributes are evaluated: (i) the risk posed by through traffic at each stopover airport and (ii) the risk posed by incoming travelers to each destination airport. The model results prioritize optimal locations (i.e., airports) for targeted dengue surveillance. The model is easily extendible to other vector-borne diseases.     

An SEIS epidemic model with transport-related infection

In this paper, an SEIS epidemic model is proposed to study the effect of transport-related infection on the spread and control of infectious disease. New result implies that traveling of the exposed (means exposed but not yet infectious) individuals can bring disease from one region to other regions even if the infectious individuals are inhibited from traveling among regions. It is shown that transportation among regions will change the disease dynamics and break infection out even if infectious diseases will go to extinction in each isolated region without transport-related infection. In addition, our analysis shows that transport-related infection intensifies the disease spread if infectious diseases break out to cause an endemic situation in each region, in the sense of that both the absolute and relative size of patients increase. This suggests that it is very essential to strengthen restrictions of passengers once we know infectious diseases appeared.     

Aeromedical transport: its hidden problems.

Air transport can move patients safely and rapidly over long distances. However, changes in altitude can have disastrous effects because diminished ambient air pressure may allow gases in closed spaces and tissues to expand rapidly. Even pressurized commercial aircraft do not maintain sea-level pressure: cabin pressures equal to those at yp to 8000 ft may be experienced, diminishing oxygen tension in proportion. Air transport is absolutely contraindicated for patients with untreated pneumothorax, gas gangrene, or air trapped in the cranium and those who have recently undergone abdominal surgery. Special considerations including a planned low-altitude flight are warrented for patients who are anemic, in respiratory or cardiac distress, or immobilized in casts, or who have been engaged in underwater diving immediately before the flight.     

The Cost of Simplifying Air Travel When Modeling Disease Spread

Background

Air travel plays a key role in the spread of many pathogens. Modeling the long distance spread of infectious disease in these cases requires an air travel model. Highly detailed air transportation models can be over determined and computationally problematic. We compared the predictions of a simplified air transport model with those of a model of all routes and assessed the impact of differences on models of infectious disease.

Methodology/Principal Findings

Using U.S. ticket data from 2007, we compared a simplified “pipe” model, in which individuals flow in and out of the air transport system based on the number of arrivals and departures from a given airport, to a fully saturated model where all routes are modeled individually. We also compared the pipe model to a “gravity” model where the probability of travel is scaled by physical distance; the gravity model did not differ significantly from the pipe model. The pipe model roughly approximated actual air travel, but tended to overestimate the number of trips between small airports and underestimate travel between major east and west coast airports. For most routes, the maximum number of false (or missed) introductions of disease is small (<1 per day) but for a few routes this rate is greatly underestimated by the pipe model.

Conclusions/Significance

If our interest is in large scale regional and national effects of disease, the simplified pipe model may be adequate. If we are interested in specific effects of interventions on particular air routes or the time for the disease to reach a particular location, a more complex point-to-point model will be more accurate. For many problems a hybrid model that independently models some frequently traveled routes may be the best choice. Regardless of the model used, the effect of simplifications and sensitivity to errors in parameter estimation should be analyzed.     

Injuries to occupants in cargo areas of pickup trucks.

Transporting passengers in the cargo area of pickup trucks is a public health safety issue in the United States. Our study compared crashes involving passengers in the cargo area with those involving passengers in the cab. We obtained data for all injury events of pickup occupants for 1990 from the California Highway Patrol. A total of 702 traffic reports coded as having passengers riding in pickup truck beds involved 1,685 passengers in the cargo area and 865 in the cab. Significantly more events involving passengers in the cargo area occurred in summer in rural areas and were noncollisions than did events with only cab passengers. Crashes with passengers in the cargo area resulted in death in 5% of passengers. Of the drivers, 81% were male and 22% were younger than 20 years. Among the 1,685 passengers in the cargo area, 65% were male, 36% were younger than 15 years, and 30% were ages 15 to 19 years. Passengers in the cargo area were more frequently ejected and more seriously injured than their counterparts in the cab. Legislation to restrict travel in truck beds and the design of restraints for this area are some measures that may reduce the risk of injury.