By NELSON BENJAMIN

JOHOR BARU: Air passengers must be screened and isolated if they are found to be ill before they board the aeroplane to safeguard the others onboard, an expert said.

Universiti Teknologi Malaysia (UTM) head of aeronautics department Prof Dr Mohammad Nazri Mohd Jaafar said a plane's ventilation system was not capable of trapping viruses like the Influenza A (H1N1).

While aircraft had extractors to constantly replace the air inside the aircraft, the process might not be fast enough to stop the spread of any airborne diseases, he said in an interview yesterday.

"This is especially so for long haul fights," he said.

Dr Mohammad Nazri said that even if the air inside a cabin was replaced from time to time, he questioned if this was fast or efficient enough to remove and discharge contaminated air.

"The best way to safeguard all the passengers is to stop and quarantine passengers who are ill before they board a plane."

Dr Mohammad Nazri, who has been involved in the research of aircraft for more than 15 years, added that aircraft should be regularly disinfected to prevent the spread of any disease.

There has been worries among many people, especially frequent fliers, about whether it is still safe to board an aircraft in the wake of the Influenza A (H1N1) pandemic.

A report from www.iata.org said the overall risk of contracting a disease from an ill person onboard an airplane is similar to that in other confined areas with high occupant density, such as a bus, a subway, or theatre.

However, the risk on airplanes could be probably lower than in many confined spaces as modern airplanes had cabin air filtration systems equipped with highly-efficient HEPA-type filters.

HEPA or high efficiency particulate air type filters have similar performance to those used to keep the air clean in hospitals, operating rooms and industrial clean rooms.

Cabin air circulation is continuous. Air is always flowing into and out of the cabin. Total airflow to the cabin is supplied at a bulk flow rate equivalent to 20 to 30 air changes per hour. This provides temperature control, and minimises temperature gradients within the cabin.