Illnesses linked with air travel
Dr Vyakarnam Nageshwar
Approximately 40 lakh passengers travel by air every month in India. Many are increasingly falling ill post air travel, causing serious concern on the number of infectious diseases associated with air travel. Outbreaks such as the one of SARS virus in the Far East in November 2002 have also been linked to aircraft transmission.
One of the primary risks is when the aircraft is delayed on the ground and the doors are closed. If the built-in ventilation system is not running, one faces the risk of breathing contaminated air. Outbreaks are facilitated when passengers remain inside the grounded aircraft for longer than 30 minutes without the ventilators functioning.
During flights, aircraft cabins have systems that control air exchanges. At cruising altitude, the ambient air outside is virtually free of microorganisms. Hence, most the aircraft built after the late 1980s re-circulate the cabin air. 10-50 per cent of the cabin air is filtered and mixed with the outside air, then introduced into the HEPA (High Efficiency Particulate Air) filters before reentering the passenger cabin. HEPA filters remove 99.99% of particles (bacteria, fungi and larger viruses). Outbreaks do occur in spite of these measures and cause great concern.
Illnesses associated with air travel are generally related to the changes in air pressure, humidity and oxygen concentration, and to relative immobility and close proximity to other passengers. Tuberculosis, influenza, plague, Pulmonary thrombo-embolism/ DVT, HANTA virus infections and viral haemorrhagic fever are some of the common respiratory illness that can spread during air travel.
Flying around 35,000 ft, the aircraft cabin pressure is equivalent to atmospheric pressure at approximately 1,500-2,500 metres above sea level, therefore within the pressurised cabin, the inspired oxygen pressure is lower than oxygen pressure at sea level that most healthy travellers do not notice. But passengers with cardio pulmonary disease, cerebro-vascular disease, anaemia and sickle cell disease can have a high risk of exacerbations of their underlying conditions.
A pulmonologist can conduct preflight evaluations of patients, which should preferably become a mandatory process for travellers suspected to have respiratory disorders. This can include a physical examination, routine blood test, Spirometry, chest X-rays and the like. A simple and effective measure of fitness to fly is whether or not you can walk 50-100 yards at a normal place, or climb one flight of stairs without becoming severely short of breath.
Seek medical help if you suffer from any of these symptoms post air travel:
Cough dry/productive
Shortness of breath
Fever on and off
Loss of appetite
Running noses/ sneezes/cold
Rashes/skin lesions
Nausea/vomiting
The writer is a consultant Pulmonologist Wockhardt Hospitals, Hyderabad