US researchers have found a significant increase in the occurrence of on-board health problems after flights witnessed a considerable increase in the number of their older passengers and extended flights.
And thus, a Lancet review has suggested that both travellers and authorities should be aware of the risks, whether they are blood clots or flu pandemics, and seek to minimise them.
Many researchers have warned that an ageing population means passengers are boarding planes with existing health problems, and the risk is further elevated because of extended flight times, reports the BBC.
The researchers found an overall link between air travel and venous thromboembolism (VTE), which occurs when a blood clot in a leg vein travels through the body to the lung.
Almost three fourth of air-travel cases of VTE were found to be linked with the lack of movement while on board.
However, economy passengers are no more likely to develop clots than their counterparts in business.
Lahey Clinic Medical Center team, led by Dr Mark Gendreau, found that the greatest risk of clot was in flights of eight hours or more, but one study claimed that the risk started to climb at four hours.
Researchers said that the improved cabin air quality and passenger seating on board should, in fact, increase some aspects of passenger wellbeing, what with new aircraft like the Airbus A380 and Boeing 777-LR extending flight times to up to 20 hours.
One can reduce the risk of VTE by taking in plenty of fluids, walking through the cabin or changing position, and using compression stockings.
The researchers advised that how individuals with compromised cardiac and pulmonary function can endure long air travel needs to be assessed, and current-screening guidelines should undergo re-assessment.
The review also found that spending long periods of time in a highly pressurised environment could prove problematic for passengers.
People with existing breathing difficulties may experience particular problems as a result of the reduced oxygen in the aircraft.
On the other hand, the expansion of gases in the body - as happens in the cabin - is risky for those who have recently had major surgery.
In fact, researchers have also revealed anecdotal evidence of bowel perforation and wounds bursting open.
Spending long periods in close quarters with others is also known to spread disease.
However, the researchers noted that the risk of on-board transmission is mainly restricted to within two rows of the passenger carrying the infection.