More than 60 entries from across the state were submitted for the contest, which was supported by the Maryland Department of Health and Mental Hygiene.
The judges felt the Boonsboro students' entry was clever and creative, said Joan Stine, director of the department's Center for Health Promotion, Education and Tobacco Use Prevention.
A submission from North Carroll Middle School in Hampstead, Md., was named best ad submitted by middle school students. Boonsboro's submission was named best ad by high school students.
The broadcast of the ads Wednesday coincided with the first day of the 9th annual Campaign for Tobacco-Free Kids Kick Butts Day.
The Boonsboro students' ad was played Wednesday during an assembly of the school's 250 sophomores. Family members of Mills, Eisel and Grim also attended.
Amanda Whipp, 15, a sophomore, was one of 10 contest semi-finalists. She also was recognized at the assembly.
Mills' father, Bill Mills, said he is going to quit smoking in response to his daughter's work.
Eisel's mother, Pam Rutherford, said she has recently quit smoking. She said she has tried to kick the habit before, but hearing about the ad made her decide to quit for good.
The script about a mother telling a daughter she is going to the store to buy deadly chemicals, in the form of cigarettes, reminded her of conversations she has had with her daughter, Rutherford said.
The three sophomores - along with other classmates - wrote scripts in a health education class taught by Tracy Bonebrake-Miller.
The students said they wrote the script in less than an hour. They said they were surprised to hear it was one of 10 semifinalists and shocked when it won.
"We did not expect to win," Eisel said.
For their winning script, the students will receive tickets to a Baltimore Orioles game and will be featured on the Maryland-Smoking Stops Here and Maryland TRASH Web sites.
When the ad was being recorded by professional actors, the students were asked to explain what tone they had in mind for various lines, Mills said.
The script was tweaked slightly and a section was added in which the students spoke their names and the name of their school.
The students said it was weird to know they might hear their voices when scanning the radio dial.
This is the public service announcement script written by three Boonsboro High School students that, as the high school grand prize winner in a state contest, began airing on radio stations Wednesday:
Speaker 1 (Mother): "Hey, I'm going into town."
Speaker 2 (Girl): "What are you going to get?"
Mother: "Oh, you know, the usual, nicotine, ammonia, carbon monoxide, arsenic ..."
Girl: "Arsenic, who are you trying to kill?"
Mother: "No one, I also have to get some formaldehyde ..."
Girl: "So are you going to kill frogs and preserve them?"
Mother: "Not quite, I also need butane, the stuff in lighter fluid; acetone, the stuff in fingernail polish remover; and benzene. It is used as motor fuel."
Girl: "Why do you need all that stuff?"
Mother: "Oh, I ran out of cigarettes."
Girl: "So you ARE trying to kill someone?"
Mother: "Yeah, myself. (Short pause) You need anything?"
Girl: "Uhhh, no thanks, I don't think they have cookies at that store."
Announcer: "I bet every one of these chemicals has a warning label telling you to 'Keep away from children.' Do you really want all of these poisons around your child?"
Dana: "This is Dana Mills."
Amanda: "Amanda Eisel."
Jessica: "And Jessica Grim from Boonsboro High School. We wrote this commercial to get people to think twice about smoking."
Dana: "Brought to you by Maryland-Smoking Stops Here and Teens Rejecting Abusive Smoking Habits."
Amanda: "Go to smokingstopshere.com and marylandtrash.com to get more involved."