Isn't "Manner Mode" Enough?

When I was a high school student, I took part in contest of a recitation in English.
This is an Essay. Look at this!!!

Do you have a cell phone? With a cell phone, you can make phone calls wherever you are, send and receive e-mail, take photos and even play games. Cell phones are very useful. Now more than half of all Japanese people have a cell phone.
About ten years ago, when people started to use cell phones, there were no rules about how to use them in public places. Gradually, rules were made. In 2003, 17 railway companies in the Tokyo area started asking passengers to obey this simple rule: turn off cell phones near priority seats, and set them to silent mode in other places on the train. The next year, 20 railway companies in the Kansai area followed the Tokyo companies' example.
Now, many people switch their cell phones to silent mode on trains, but few people turn them off. They say, "The phone won't ring out loud, so it won't cause trouble to others. Sometimes I'm waiting for an emergency call. Isn't it enough to set my cell phone to silent mode?"
In fact, the answer is no. The electromagnetic waves from cell phones are dangerous for some people. Even if you do not make a phone call, a cell phone keeps generating electromagnetic waves unless you turn it off. A cell phone could cause the malfunction of medical devices such as pacemakers. Pacemakers are used by people with heart problems. Some pacemaker users say, "I feel nervous just at the sight of someone with a cell phone, so I don't like getting on the train." For such people, it is essential that all passengers turn off their cell phones near priority seats.
Cell phones are still new in our society. We still need to think about the best ways to use them.

I was very keyed up then. So my legs trembled under me and forgot last part. But I could talk all things. Through this experience, I think I could grow up so much! I want to challenge a contest like this again someday if I get any opportunity.(367 words)