A number of possible health hazards of air travel have been investigated.
On an airplane, people sit in a confined space for extended periods of time, which increases the risk of transmission of airborne infections. [1] [2] For this reason, airlines place restrictions on the travel of passengers with known airborne contagious diseases (e.g. tuberculosis). During the severe acute respiratory syndrome (SARS) epidemic of 2003, awareness of the possibility of acquisition of infection on a commercial aircraft reached its zenith when on one flight from Hong Kong to Beijing, 16 of 120 people on the flight developed proven SARS from a single index case. [3]
There is very limited research done on contagious diseases on aircraft. The two most common respiratory pathogens to which air passengers are exposed are parainfluenza and influenza. [4] In one study, the flight ban imposed following the attacks of September 11, 2001 was found to have restricted the global spread of seasonal influenza, resulting in a much milder influenza season that year, [5] and the ability of influenza to spread on aircraft has been well documented. [1] There is no data on the relative contributions of large droplets, small particles, close contact, surface contamination, and no data on the relative importance of any of these methods of transmission for specific diseases, and therefore very little information on how to control the risk of infection. There is no standardisation of air handling by aircraft, installation of HEPA filters or of hand washing by air crew, and no published information on the relative efficacy of any of these interventions in reducing the spread of infection. [6]
Air travel, like other forms of travel, radically increases the speed at which infections spread around the world, as viruses rapidly spread to large numbers of people living across the world. Human and cargo traffic greatly facilitates the spread of pathogens across the world, [7] [8] for example during the COVID-19 pandemic.
Deep vein thrombosis (DVT) is the third most common vascular disease next to stroke and heart attack. It is estimated that DVT affects one in 5,000 travellers on long flights. [9] [10] Risk increases with exposure to more flights within a short time frame and with increasing duration of flights. [10] According to a health expert in Canada, even though the risk of a blood clot is low, given the number of people who fly, it is a public health risk. [9] It is reported in 2016 that the average distance between seat rows has declined to 79 centimetres (31 in), from over 89 centimetres (35 in), while the average seat size has shrunk to 43 centimetres (17 in) from 46 centimetres (18 in) in the previous two decades. [9]
Flying 12 km (39,000 ft) high, passengers and crews of jet airliners are exposed to at least 10 times the cosmic ray dose that people at sea level receive. Every few years, a geomagnetic storm permits a solar particle event to penetrate down to jetliner altitudes. Aircraft flying polar routes near the geomagnetic poles are at particular risk. [11] [12] [13] There is also increased radiation from space. [14]
Other possible hazards of air travel that have been investigated include airsickness and chemical contamination of cabin air.
In low risk pregnancies, most health care providers approve flying until about 36 weeks of gestational age. [15] Most airlines allow pregnant women to fly short distances at less than 36 weeks, and long distances at less than 32 weeks. [16] Many airlines require a doctor's note that approves flying, specially at over 28 weeks. [16]
The common cold or the cold is a viral infectious disease of the upper respiratory tract that primarily affects the respiratory mucosa of the nose, throat, sinuses, and larynx. Signs and symptoms may appear in as little as two days after exposure to the virus. These may include coughing, sore throat, runny nose, sneezing, headache, and fever. People usually recover in seven to ten days, but some symptoms may last up to three weeks. Occasionally, those with other health problems may develop pneumonia.
Severe acute respiratory syndrome (SARS) is a viral respiratory disease of zoonotic origin caused by the virus SARS-CoV-1, the first identified strain of the SARS-related coronavirus. The first known cases occurred in November 2002, and the syndrome caused the 2002–2004 SARS outbreak. In the 2010s, Chinese scientists traced the virus through the intermediary of Asian palm civets to cave-dwelling horseshoe bats in Xiyang Yi Ethnic Township, Yunnan.
Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, gliders, hang gliders, parachutes, or anything else that can sustain flight. Use of air travel began vastly increasing in the 1930s: the number of Americans flying went from about 6,000 in 1930 to 450,000 by 1934 and to 1.2 million by 1938. It has continued to greatly increase in recent decades, doubling worldwide between the mid-1980s and the year 2000. Modern air travel is much safer than road travel.
An asymptomatic carrier is a person or other organism that has become infected with a pathogen, but shows no signs or symptoms.
In medicine, public health, and biology, transmission is the passing of a pathogen causing communicable disease from an infected host individual or group to a particular individual or group, regardless of whether the other individual was previously infected. The term strictly refers to the transmission of microorganisms directly from one individual to another by one or more of the following means:
Flu season is an annually recurring time period characterized by the prevalence of an outbreak of influenza (flu). The season occurs during the cold half of the year in each hemisphere. It takes approximately two days to show symptoms. Influenza activity can sometimes be predicted and even tracked geographically. While the beginning of major flu activity in each season varies by location, in any specific location these minor epidemics usually take about three weeks to reach its pinnacle, and another three weeks to significantly diminish.
An emergent virus is a virus that is either newly appeared, notably increasing in incidence/geographic range or has the potential to increase in the near future. Emergent viruses are a leading cause of emerging infectious diseases and raise public health challenges globally, given their potential to cause outbreaks of disease which can lead to epidemics and pandemics. As well as causing disease, emergent viruses can also have severe economic implications. Recent examples include the SARS-related coronaviruses, which have caused the 2002–2004 outbreak of SARS (SARS-CoV-1) and the 2019–2023 pandemic of COVID-19 (SARS-CoV-2). Other examples include the human immunodeficiency virus, which causes HIV/AIDS; the viruses responsible for Ebola; the H5N1 influenza virus responsible for avian influenza; and H1N1/09, which caused the 2009 swine flu pandemic. Viral emergence in humans is often a consequence of zoonosis, which involves a cross-species jump of a viral disease into humans from other animals. As zoonotic viruses exist in animal reservoirs, they are much more difficult to eradicate and can therefore establish persistent infections in human populations.
Influenza, commonly known as "the flu" or just "flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms begin one to four days after exposure to the virus and last for about two to eight days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia from the virus or a subsequent bacterial infection. Other complications include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease.
The 2009 swine flu pandemic, caused by the H1N1/swine flu/influenza virus and declared by the World Health Organization (WHO) from June 2009 to August 2010, was the third recent flu pandemic involving the H1N1 virus. The first identified human case was in La Gloria, Mexico, a rural town in Veracruz. The virus appeared to be a new strain of H1N1 that resulted from a previous triple reassortment of bird, swine, and human flu viruses which further combined with a Eurasian pig flu virus, leading to the term "swine flu".
In public health, social distancing, also called physical distancing, is a set of non-pharmaceutical interventions or measures intended to prevent the spread of a contagious disease by maintaining a physical distance between people and reducing the number of times people come into close contact with each other. It usually involves keeping a certain distance from others and avoiding gathering together in large groups.
Airborne transmission or aerosol transmission is transmission of an infectious disease through small particles suspended in the air. Infectious diseases capable of airborne transmission include many of considerable importance both in human and veterinary medicine. The relevant infectious agent may be viruses, bacteria, or fungi, and they may be spread through breathing, talking, coughing, sneezing, raising of dust, spraying of liquids, flushing toilets, or any activities which generate aerosol particles or droplets.
Influenza prevention involves taking steps that one can use to decrease their chances of contracting flu viruses, such as the Pandemic H1N1/09 virus, responsible for the 2009 flu pandemic.
A fomite or fomes is any inanimate object that, when contaminated with or exposed to infectious agents, can transfer disease to a new host.
Infection in childcare is the spread of infection during childcare, typically because of contact among children in daycare or school. This happens when groups of children meet in a childcare environment, and there any individual with an infectious disease may spread it to the entire group. Commonly spread diseases include influenza-like illness and enteric illnesses, such as diarrhea among babies using diapers. It is uncertain how these diseases spread, but hand washing reduces some risk of transmission and increasing hygiene in other ways also reduces risk of infection.
A focus of infection is a place containing whatever epidemiological factors are needed for transmission of an infection. Any focus of infection will have a source of infection, and other common traits of such a place include a human community, a vector population, and environmental characteristics adequate for spreading infection.
A respiratory droplet is a small aqueous droplet produced by exhalation, consisting of saliva or mucus and other matter derived from respiratory tract surfaces. Respiratory droplets are produced naturally as a result of breathing, speaking, sneezing, coughing, or vomiting, so they are always present in our breath, but speaking and coughing increase their number.
Air China Flight 112 was a scheduled international passenger flight on 15 March 2003 that carried a 72-year-old man infected with severe acute respiratory syndrome (SARS). This man would later become the index passenger for the infection of another 20 passengers and two aircraft crew, resulting in the dissemination of SARS north to inner Mongolia and south to Thailand. The incident demonstrated how a single person could spread disease via air travel and was one of a number of superspreading events in the global spread of SARS in 2003. The speed of air travel and the multidirectional routes taken by affected passengers accelerated the spread of SARS with a consequential response from the World Health Organization (WHO), the aviation industry and the public.
Allison Joan McGeer is a Canadian infectious disease specialist in the Sinai Health System, and a professor in the Department of Laboratory Medicine and Pathobiology at the University of Toronto. She also appointed at the Dalla Lana School of Public Health and a Senior Clinician Scientist at the Lunenfeld-Tanenbaum Research Institute, and is a partner of the National Collaborating Centre for Infectious Diseases. McGeer has led investigations into the severe acute respiratory syndrome outbreak in Toronto and worked alongside Donald Low. During the COVID-19 pandemic, McGeer has studied how SARS-CoV-2 survives in the air and has served on several provincial committees advising aspects of the Government of Ontario's pandemic response.
In epidemiology, a non-pharmaceutical intervention (NPI) is any method used to reduce the spread of an epidemic disease without requiring pharmaceutical drug treatments. Examples of non-pharmaceutical interventions that reduce the spread of infectious diseases include wearing a face mask and staying away from sick people.
The transmission of COVID-19 is the passing of coronavirus disease 2019 from person to person. COVID-19 is mainly transmitted when people breathe in air contaminated by droplets/aerosols and small airborne particles containing the virus. Infected people exhale those particles as they breathe, talk, cough, sneeze, or sing. Transmission is more likely the closer people are. However, infection can occur over longer distances, particularly indoors.
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