At 62 years old, she is a well-known waste collector who does the job not to earn a living, but to use her earnings for the benefit of others in Phu Thuong Commune, the central province of Thua Thien Hue.
Nguyen Thi Doi said she resorted to her unusual vocation about four years ago when, on the way to a pagoda festival, she came across an old woman who collected wasted plastic bags to earn some money to meet her own expenses and be able to buy some sweets for her grandchildren.
The woman's story inspired Doi to do the same to earn money for charities that she had contributed to for many years.
However, the work is not as easy it sounds, said Doi, who lives with her children and grandchildren.
In the first month, she only managed to collect a little more than a kilogram of plastic bag waste, she said.
Doi then remembered the waters full of waste bags at the Thuan An fishing port, and she collected nearly 15 kilograms of bags on her first day of working there.
"After that, whenever I see wasted plastic bags at the port, I would feel very happy. My fish trading friends can sometimes suffer losses, but I always gain benefits from collecting waste," she said.
The old woman said sometimes there were so many bags that she had to work from early in the morning until 1-2 p.m. without taking a break, or call her children for help.
"My children are familiar with it, so whenever I call them, they would know that I'm asking them to help collect waste. If we don't collect them, others would burn them or let them drift back into the sea, and the sea would be polluted."
Doi said local seafood traders also give her waste bags for free when they learnt about her charitable work.
She said in the early days, she would collect bags and give them all to a local woman so the latter could clean them and sell them. But a couple of months later, Doi found that the woman cheated her and the money was not given to charity
Since then Doi and her children have been doing everything on their own - collecting bags, cleaning them at home, and selling them.
At first they couldn't find anyone to sell the bags without being asked to lower prices for various reasons, Doi said that she planned to quit the venture in despair.
However, a friend of her son once came to visit the family and found the bags were maintained well, so he introduced them to a factory recycling plastic bags in Hue town. Knowing Doi's real motive, the factory agreed to buy plastic bags at stable prices, between VND14,000-15,000 (US$0.67-0.71) per kilogram.
Doi said when she has collected several hundred kilos of the bags, she would call the factory to collect them. During the winter, the factory keeps asking her for wasted bags, but "due to rains and wind, we can't dry bags, so we don't dare sell them. Moreover, the source of plastic bags at the port is already stable," she said.
With the earnings from selling waste bags, Doi has more money to give charities, and organize visits to old people's homes and orphanages and give them gifts. She also asks her children to save up in case her earnings aren't enough.
"What Doi does is really respectable and admirable," said Le Viet Thinh, head of the hamlet where Doi resides.
Meanwhile, Linh, who trades in seafood in Phu Vang, praised Doi for her environmental protection efforts. "She totally deserves some environmental award," he said.
But, Doi said she never thinks about awards, but "I only want to collect waste plastic bags to do something good."
She said some young people teased her by asking her to teach them to collect waste so she can retire, but "I think as long as my health is good, I'll continue doing it."