Giang Huy, 17, holds an empty cement sack in one hand and shakes it constantly while beating it at the other end for all the dust and residues to come off.
Inhaling cement dust is part of the job for more than 70 families living along a canal in District 8 on the outskirts of Ho Chi Minh City. They are given used cement sacks that they have to clear of all dust for resuse.
Although the dust flies all around him and covers his body with a white film, Huy never wears a face mask.
"Doing this job, you sweat all the time, so putting on a face mask would be annoying, sometimes makes it difficult to breathe.
"If dust flies into my eyes, I'll use my T-shirt to clean it," the boy told local news website VnExpress. His clothes were already coated with dust.
Huy said he was not eligible for hiring by companies at his age, so he had to work with the sacks from 7 a.m. to 5 p.m for VND70,000 (less than US$4) a day.
He said the job can only be done on sunny days, and when it rains, he does not earn anything.
The boy from Long An Province neighboring HCMC said the job did not pay much but "I would do anything that makes money, as long as it's not illegal.
"My parents back home are very poor and didn't have money for me to continue schooling. I quit at grade six and began to work.
"I'll work for a couple of years and my savings will be enough to open a café."
Huy said the job was not hard as working as a porter or doing other manual jobs at construction sites, but people have to be in the middle of sunshine and dust all day long.
The job includes shaking the sacks and washing them, if they're plastic. Paper sacks only need shaking.
Nguyen Thi Tuyet, a 40-year-old who has been doing the job for 20 years, said the job first appeared in early 1960s but "prospered" in the early 1980s with many people from the Mekong Delta joining the business.
Tuyet said people have started to quit the job because it does not earn much and there are not as many sacks to dust off anymore.
Still, some people see the job as good enough.
A woman named Hoa, 43, from Dong Thap Province has been doing the job for more than 20 years, for just VND30,000-60,000 a day.
Hoa has two children going to school in Dong Thap and the job lets her save several tens of thousands of dongs a day to send them at the end of the month.
"The job doesn't earn plenty of money. But I don't demand much. It's okay that you're doing a legal job and don't have to beg money from anyone," she said.
Van Anh, 45, of Soc Trang Province, is his own boss. He buys the sacks from construction sites at VND500 each, cleans them and sells them to recyclers at VND700.
People in the village say they know the job pollutes the environment but they have no other choice.
"This job may not last long as people nearby have complained that we're causing too much pollution," said another sack shaker in the area.
"Well, we will just work till we can. We cannot find another job at the moment."