BEIJING - This 74-year-old granny has never thought of picking up a tangerine peel off the floor by her bedside and throwing it in the dustbin.

But cigarette butts on Tian'anmen Square? Definitely.

For 17 years, Liu Yuzhen has come with a plastic bag to Tian'anmen Square at about 5 am, a little bit before the first security guards, and voluntarily picked up the scattered garbage on the square.

"I don't sweep the floor at home but I never let go of a single cigarette butt on the square," said Liu Yuzhen. "The square is the window of Beijing, not my bedroom."

Getting up before the sun rises, Liu prepares seafood flavor instant noodles, sometimes with an egg, for her husband, who has been bedridden for years. After working for three or four hours, Liu takes the bus back home around 8 am, before the tourists from home and abroad swarm in and her family wakes up from dreams.

"When I started to pick up cigarettes, my then 4-year-old granddaughter said I was like a spy, sneaking out every day," kidded Liu.

"She thought I was doing something cool, like going to a candy factory. It's just something cool she can't understand, though."

Liu said she was smart because she has been "taking advantage of her seniority" as the square beautician.

"When people see me bend down collecting cigarette butts, sweating all over under the scorching sun, they usually pick up the litter they just dropped," said Liu.

"I make use of people's sympathy," Liu laughed.

Liu comes to the square so early that there are only a few people there.

"And I sing, the whole square seems to be my stage."

Liu said she used to learn vocal music from noted operatic soprano Guo Lanying.

"They like it when I sing," Liu said, pointing to some photographers on the square not far away.

"You are talking with the singer of the square," three photographers shouted back.

Besides old-time songs, Liu loves singing traditional commercial babbles as well, which vendors in old China used to sing to attract traders.

Liu said not many people know how to sing the old tunes, but whenever she was humming, people were interested and willing to learn a piece or two from her.

"They call me the 'golden voice' of the square," said Liu. "I like the title."

However, despite Liu's devotion to the battle against garbage, her family has been worrying about her health.

"She's getting old," said Wu Xiuyun, Liu's daughter. "She now suffers from tinnitus and she may faint anytime."

Wu said Liu was sensitive to sunlight and had to wear long sleeves even in summer, when the temperature soars.

"She even burned herself once as a cigarette butt she picked up was still on fire," said Wu. "The butt ignited the garbage in her bag and her trousers."

Wu bought her mother a mobile phone designed for seniors, with a big emergency button on top in case Liu fainted.

"They even let me have an identification card dangling around my neck with my address and daughter's phone number on it in case I'm lost," Liu said. "They treat me like a kid."

"Which she is," Wu argued back.

As the cleaner who has worked the longest on the square, Liu said the square is cleaner than years ago.

"She possesses good merits," said Jose Martinos, a Brazilian tourist at the square, on seeing Liu rushing forward suddenly after discovering a cigarette butt lying ahead.

"She's a fun auntie and most of us know her," said a cleaner on the square surnamed Tang. "Work is fun in her company."