Photographer Alex Masi's chance shot of a young girl in Bhopal transformed both of their lives

Alex Masi was taking shelter during monsoon season in Bhopal, India, when he noticed a young girl dart out to shake off the heat of the day. His chance shot (above) ended up winning an award – and what Masi did next transformed not only the life of his subject and her family, but also his own

Masi's image showed Poonam, then seven, drenched but ecstatic, face turned to the heavens, haunches trailing in mud (Alex Masi)

On 24 August 2009, as monsoon season arrived in central India, Alex Masi took a picture… and lives changed. He was in Bhopal, photographing a boy called Sachin Jatev, who had leg paralysis and skeletal deformity, possibly as a result of the 1984 gas leak that devastated the area. "It began to rain very hard," recalls Masi, now 34, an Italian-born, London-based photojournalist who last year also photographed the heavily polluted Bhopal region 30 years after the disaster for The New Review. "It hadn't rained for a while, so the children went a bit crazy. In that moment, I captured Sachin's younger sister Poonam refreshing in the rain. I was taking shelter under a plastic sheet and she was right in front of me. For a brief moment she took in the rain and then she realised I was taking photos and ran away."

The image showed Poonam, then seven, drenched but ecstatic, face turned to the heavens, haunches trailing in mud. It had, says Masi, "a feeling of freedom and emancipation, despite the setting." In 2011, it won the Photographers Giving Back Photo Award, instigated to benefit the subjects of photojournalism. Masi received a $5,000 grant, which he used to transform the lives of Poonam and her family, as well as his own. It has created a bond between subject and photographer that is rare and powerful.

"When you photograph people, sometimes you feel you are taking something from them," says Masi. "I try to explain I am not there to help directly, but if they let me take a photograph, maybe somebody will help. I am the bridge between the readers and the subjects. That is my role. I don't want to give them the feeling that if I take their photograph it will change their life. But in this case, it did."

In collaboration with the family and Neelam Nandan Nagar, a local translator who handled cultural as well as linguistic differences, Masi explored his options. They decided that rather than simply hand over the money, they would find ways to lift the family out of poverty over the longer term. A brick house was constructed to replace their shack of mud and dung. A cart was purchased so that Suresh, their father, could sell vegetables rather than work as a labourer – a simple investment that doubled his regular income. The focus then went on the five children, particularly the youngest three, sisters Poonam and Jyoti and their brother Ravi (now 12, 14 and 15 years old, respectively).

"We put them in a small private school," says Masi. "Ravi has since decided that he wanted to work – we respected that choice and he no longer attends school – but his sisters are still in education. We hope to keep them at school and then college if possible." With the initial grant spent, Masi is crowdfunding their education as well as his own annual visit to India to document the family's progress. Ultimately, he hopes to set up an NGO to educate more children in the area.

It is an extraordinary commitment, but Masi felt he had no choice. "After spending the $5,000, I saw the job was not complete," he says. "I could see the way the family's lives changed. I wanted to stay involved, to see them growing up."

Poonam Jatev, at the start of a school day, with Alex Masi (Alex Masi)

He admits that there are potential concerns: the family may become overly dependent on him, while some may query whether it is right for a Westerner to have such an influence on the lives of a poor Indian family. "We discuss everything," he explains. "We don't tell them what to do: we ask. We don't force them to do anything they don't want and we are not paying for something they could pay for themselves. We don't want them to become addicted to us. Something could happen to us, so they must create a system for themselves."

The sisters enjoy school. "At first, when one was off sick, the other would stay home too, but now they don't want to miss a lesson," says Masi. Their ambition is to become teachers.

The family were initially wary of their benefactor, but Masi believes that they now understand what he is trying to do. "They are pretty friendly with me," he says. "They are pleased to see me, but if I spend too many days in a row taking photographs, they get a little bored." He also benefits from the relationship. "I spend a lot of time seeing people suffering, in desperate situations, in Iraq, Afghanistan and Nigeria," he says. "This work allows me to see the opposite, how people can come back from a bad situation. It keeps me sane and shows me that my work can have real impact."

For more: poonam.alexmasi.co.uk; facebook.com/poonam.jatev. To help fund Poonam and Jyoti: gofundme.com/Poonam-Tale-of-Hope