Q: Is air travel a high-risk transmission environment?

A: No. The risk of transmission on aeroplanes is very low. Travelers who develop SARS symptoms, as well as other respiratory illnesses accompanied by a fever, are advised not to undertake travel until fully recovered.

Over 200 million passengers have flown since early March, approximately one-third in Asia. Since the beginning of April, six flights carried SARS suspect cases on board, but no cases of in-flight transmission have occurred. No cases of SARS suspect cases on board have occurred since effective screening measures were introduced.

Q: Do aircraft have adequate ventilation?

A: Yes. The configurations of the air circulation system for commercial aircraft are designed to the specifications of international aviation regulations as well as guidelines of aircraft manufacturers, including Boeing and Airbus.

* Circulation: In flight, fresh air is introduced into the cabin continuously. The entire cabin air volume is exchanged every three minutes.

* Airflow: The airflow movement is designed to minimize the potential for the spread of bacteria through the cabin.

* Filters: Most major airlines install HEPA (high-efficiency particulate air) filters, which are highly efficient in removing dust and airborne contaminants such as droplets, bacteria and large viral particles. This filter type is also used by hospital operating theatres.

* Humidity/air quality: As the humidity is quite low, this makes the cabin environment quite inhospitable to germs' survival and growth.

Q: Is there a risk of getting infected by another passenger on board a flight?

A: Information to date suggests that there is no transmission of infection from persons with no symptoms of the disease (such as fever, coughing or sneezing).

Q: Are passengers at risk from the cabin crew?

A: No, all cabin crew should be medically fit and physically capable to fly and fulfil their duties on board. If they feel unwell or have symptoms such as fever or coughing, they will not be working.

Q: Should passengers take any precautions when traveling on aeroplanes?

A: Travelers from SARS-hit countries who demonstrate symptoms of SARS such as fever and respiratory symptoms should postpone further travel and seek medical advice immediately.

All persons should observe good personal hygiene. Wash hands frequently.

If passengers cough or sneeze while on board, they should cover their mouth and nose, and wash their hands afterwards.

Q: Should passengers wear masks when traveling by air?

A: Those who feel more comfortable for personal reasons may choose to wear a mask. However, the best defence against SARS is to maintain good personal and environmental hygiene (such as frequent hand washing).

Q: What is the risk for a person sitting next to a SARS-infected passenger on board a flight?

A: With the new screening methods in place in SARS-hit countries, the chances of a potentially sick passenger traveling on board an aircraft and transmitting the disease to others is very low.

Current data supports the view that a person is not infectious unless they are sick or symptomatic. Based on available epidemiological data, the vast majority of transmissions have occurred as a result of respiratory droplets spread through close person-to-person contact.

If an apparently healthy passenger boarded a flight and then proceeded to develop respiratory symptoms during the flight, guidelines from the World Health Organization, local departments of health and the centers for disease control provide for airline crew to place a face mask on that passenger, isolate them where possible and block off the vacated seat if possible. A dedicated toilet will be blocked off for use by the suspect passenger. Therefore, the risk of transmitting the disease is very low.

(China Daily May 8, 2003)