阅读理解
Commuter trains are often stuffy and crowded, and they frequently fail to run on time. As if that were not bad enough, physicist Hondon published a paper that gave commuters yet another reason to feel uncomfortable.
Dr. Hondon examined mobile-phone usage in enclosed spaces such as railway carriages, buses and lifts, all of which are, in essence, metal boxes. His model predicted that a large number of passengers crowded together, all talking, sending text messages, or browsing the web on their phones, could produce levels of electromagnetic radiation that exceed international safety standards. That is because the radio waves produced by each phone are reflected off the metal walls of the carriage, bus or lift. Enough radiation escapes to allow the phone to communicate with the network, but the rest fills the inside of the carriage with bouncing microwaves.
This sounds worrying. However, in a paper published recently, Jaime Ferrer and Lucas Fernández-Seivane from the University of Oviedo in Spain, dispute Dr. Hondou''s findings. They conclude that the level of radiation is safe after all.
In their opinion, while each phone produces radiation that bounces around the car, the passengers absorb some of it, which has the effect of reducing the overall intensity. Dr. Hondon''s model, in short, was valid only in the case of a single passenger sitting in an empty carriage with an active mobile phone on every seat.
According to Dr. Ferrer and his colleagues, Dr. Hondon overestimated the level of electromagnetic radiation. When one is sitting on a train, they found, the most important sources of radiation are one''s own phone, and those of one''s immediate neighbours. The radiation from these sources far exceeds that from other phones or from waves bouncing around the carriage. And all these sources together produce a level of radiation within the bounds defined by the ICNIRP, the international body that regulates such matters.
People concerned about the effects of mobile-phone radiation are unlikely to take much comfort from Dr. Ferrer''s results. Indeed, Dr. Ferrer says he was surprised at how little research has been done in this area.
Yet both Dr. Hondon''s results and Dr. Ferrer''s are based on mathematical models. Their models make assumptions about the physical properties of train carriages and their passengers, and both assume that the radiation is uniformly distributed rather than gathered into "hot spots". But if the debate about the safety of mobile phones is to be resolved, there must be less reliance on models, and more emphasis on hard experimental data.
单选题
Why the paper published by Dr. Hondon makes the commuters worried?