As April 30 approaches, marking 40 years since the end of the Vietnam War, people in Vietnam with severe mental and physical disabilities still feel the lingering effects of Agent Orange.

Respiratory cancer and birth defects amongst both Vietnamese and U.S. veterans have been linked to exposure to the defoliant. The U.S. military sprayed millions of gallons of Agent Orange onto Vietnam's jungles during the conflict to expose Vietnamese soldier troops.

Reuters photographer Damir Sagolj travelled through Vietnam to meet the people affected, four decades on.

If you are on the plane taking off from Danang airport in Vietnam, look through the window on your right - between the departure building and the yellow wall separating the airport from densely populated neighbourhoods - you will see an ugly scar on the already not very pretty face of the Vietnam War.

This is where barrels of Agent Orange were kept in the airport U.S. military used to spray the defoliant across the country. Now, more than forty years later, the spot is finally being decontaminated.

The cleaning operation of the area that was used for storing Agent Orange is seen from a plane taking off from Danang international airport April 13, 2015. Agent Orange was stored at Danang airbase and sprayed from U.S. warplanes to expose Vietnamese troops from the North and destroy their supplies, in jungles along the border with Laos. Since 2012, both the U.S. and Vietnam have been conducting a clean-up operation at the site. Photo: Damir Sagolj 

When covering an anniversary, it’s easy to fall into the trap of a “before and after” cliché or, even worse, to try to do something different but irrelevant.

Even so, I wanted to do a story on the legacy of Agent Orange. There were several raised eyebrows around me, as colleagues asked: Couldn't I find something new instead of retelling a story told over and over already?

Deformed foetuses are seen inside glass containers in an exhibition room at Peace Village in Tu Du hospital in Ho Chi Minh City April 14, 2015. Doctors at the hospital attribute the high incidence of deformities to the use of Agent Orange during the Vietnam War. According to the head of the Peace Village, more than two-thirds of its over 60 patients are from areas that were heavily sprayed by Agent Orange and their health conditions are linked to the use of the defoliant. Photo: Damir Sagolj 

I can’t say where and when I heard it but I remember the advice well: no matter how many times the story has been done and how many people have done it, do it as if you are the first and only one to witness it. I listened to this advice so many times in the past and I listened to it now.

Such assignments have rules, among the most important being the longer you spend in the unknown, the more chance you have of getting strong pictures.

So a Vietnamese colleague and I set off to travel around Vietnam, a country stretching more than 1,500 kilometres from north to south, with a great many people still affected by Agent Orange.

Pham Thi Phuong Khanh is fed by a hospital staff member at the Peace Village in Tu Du hospital in Ho Chi Minh City April 14, 2015. Both of Pham Thi Phuong Khanh's parents were exposed to Agent Orange during the Vietnam War. Photo: Damir Sagolj

The Vietnam Association of Victims of Agent Orange/Dioxin (VAVA) told Reuters that more than 4.8 million people in Vietnam have been exposed to the herbicide and over 3 million of them have been suffering from deadly diseases.

Nguyen Thi Van Long (R) and her best friend Dinh Thi Huong, who is deaf and mute, spend time together at Friendship village, a hospice for Agent Orange victims outside Hanoi April 8, 2015. The fathers of both girls were soldiers who were exposed to the Agent Orange during the Vietnam war and health officials link the girls' health conditions to the defoliant. Some 120 children and 60 Vietnamese veterans stay at Friendship village, which was established in 1998. Photo: Damir Sagolj 

But soon after I started taking pictures and talking to victims and their relatives, I realised I would need to think again about how to do this story. My immediate and natural reaction was to get closer, almost into the face of a victim, to show what has happened to human bodies.

A forensic photography approach, almost. In a hospice outside Hanoi, after a few strong portraits of a kid born with no eyes and other victims whose bodies are horribly twisted, my original plan felt wrong. The faces and eyes in the pictures hurt; the focus is there but I may be missing things around, possibly even the story itself.

63-year-old former soldier, Nguyen Hong Phuc, sits on the bed with his son Nguyen Dinh Loc, 20, who is recovering from tumour surgery at Friendship village, a hospice for Agent Orange victims, outside Hanoi April 8, 2015. Nguyen Dinh Loc has serious mental and physical problems that his family and doctors link to his father's exposure to Agent Orange. His father joined the military after the U.S. army stopped using Agent Orange in 1971, but lived in areas heavily contaminated by it, including near Danang airport, where the chemical defoliant was stored. Photo: Damir Sagolj

I wanted to put it all in the context of today’s Vietnam, forty years on. To see victims of the second and third generations, where and how they live. To learn why children and grandchildren of people affected are still being born with disabilities, to find out if people know about the dangers, and if so when they found out.

And to take pictures of all that.

As we got closer to the former front lines travelling from the north, the number of cases increased. We kept in touch with VAVA, the main association helping victims, and they gave us much needed information, including the number of victims and where they live.

Throughout the assignment, VAVA and other local officials together with family members confirmed that the health conditions of people we met and photographed are linked to Agent Orange as their parents or grandparents were exposed to it.

In yet another village, Le Van Dan, an ex Vietnamese soldier from the South, wearing a worn-out military jacket, told me how he was sprayed directly from the U.S. planes not far from his home today.

Le Van Dan (C) looks at his disabled grandson Le Van Tam (L) as his daughter feeds another sick grandson in their family house in Phuoc Thai village, outside Danang April 12, 2015. Le Van Dan, a former artillery soldier, said he was exposed to Agent Orange more than once, including being directly sprayed by U.S. planes near his village before he joined the military. Health officials confirmed two of his grandsons’ disabilities are due to his exposure to the defoliant, Le Van Dan said. Photo: Damir Sagolj 

As the tough man spoke through broken teeth, two of his grandsons in a room behind the kitchen were given milk provided by a government aid agency. Both kids were born severely disabled, doctors say because of Agent Orange.

In a small village in Thai Binh province, in a cold room empty of any furniture, Doan Thi Hong Gam shrank under a light blue blanket. The room’s dirty walls suggest anger and some sort of struggle. She’s been kept in isolation since the age of sixteen because of her aggressiveness and severe mental problems. She is 38 now.

38-year-old Doan Thi Hong Gam, who suffers from severe mental as well as physical health problems, covers herself with a blanket in an empty room in Thai Binh province, northern Vietnam April 10, 2015. Doan Thi Hong Gam spends her time in an empty room. She is kept isolated because of aggressive behaviour linked to mental health problems. Her father, who suffers from serious heath problems, served as a Vietnamese soldier from the North during the war and said he was exposed to Agent Orange while fighting in the Central Highlands. Doan Thi Hong Gam’s family and health workers believe her health problems are linked to Agent Orange. Photo: Damir Sagolj

I took pictures of the poor woman for about 15 minutes. They were possibly the strongest frames I have taken in a long time. Her father, a former soldier lying in the bed in a room next to hers, also very sick, was exposed to Agent Orange during the war.

Then another village and another picture. On a hill above his home, former soldier Do Duc Diu showed me the cemetery he built for his twelve children, who all died soon after being born disabled. There are a few extra plots next to the existing graves for where his daughters, who are still alive but very sick, will be buried.

Former soldier Do Duc Diu prays at the cemetery where twelve of his children are buried, after showing the graves to reporters, near his house in Quang Binh Province in central Vietnam April 11, 2015. Twelve of his fifteen children died from illnesses that the family and their doctors link to Do Duc Diu's exposure to Agent Orange. Do Duc Diu served as a Vietnamese soldier from the North in the early 70s in areas that were heavily contaminated by Agent Orange. He only found out about the possible dangers of Agent Orange before his last child was born in 1994. He said that if he had known about the possible effects of Agent Orange he would not have had children. Before he found out about the effects of Agent Orange, Do Duc Diu said that he and his wife visited many spiritual leaders and prayed at different shrines as they attributed their children's sickness to their ill-fated destiny. Photo: Damir Sagolj

The man was also a Vietnamese soldier exposed to the toxic defoliant. For more than twenty years he and his wife were trying to have a healthy child. One by one their babies were dying and they thought it was a curse or bad luck, so they prayed and visited spiritual leaders but that didn’t help.

They found out about Agent Orange only after their fifteenth child was born, also sick. I took a picture of the youngest daughter. It was not an easy thing to do.

Lai Van Manh rests in bed as his father Lai Van Bien receives guests in their house in Tuong An village, in Thai Binh province in northern Vietnam April 9, 2015. Lai Van Bien, a former intelligence officer in the Vietnamese army in the North, said that during the Vietnam War he served in an area that was heavily contaminated by Agent Orange. Lai Van Bien and his wife now care for their two physically and mentally disabled sons whose health condition the family and local officials link to the effects of Agent Orange. Photo: Damir Sagolj 

Village after village, strong pictures and even stronger stories emerge. My camera stayed at a distance. I shot through mosquito nets and against the light, I shot details and reflections. We took many notes trying not to miss any important details needed to build an accurate picture. Then we drove further south.

Back in Danang, next to its international airport, we visited a young couple who have lived and worked there since late 1990s. When they first moved there the man used to go fishing, collecting snails and vegetables to bring home to eat.

The family was poor and all food was welcomed. What he didn't know was that Agent Orange, which used to be stored nearby, had contaminated the waters and everything around the lake situated next to the airstrip.

His daughter was born sick in 2000 and died aged seven. Their son was born in 2008, also sick with the same symptoms as his late sister. I took pictures and then we drove the family to the hospital for the boy’s blood transfusion. The blind and very sick boy held my finger and later blew a kiss into the emptiness. I saw it from afar as I walked away.

7-year-old Nguyen Van Tuan Tu, who suffers from serious health problems, is looked after by a family member under a mosquito net in their house near the airport in Danang, in central Vietnam April 12, 2015. When Nguyen Van Tuan Tu's father started working at Danang International Airport in 1997, he was not aware of the health risks associated with Agent Orange and he collected fish and snails from a contaminated lake nearby for the family to eat. His first child to be born after he started working at the airport was born in 2000 and died in 2007. Nguyen Van Tuan Tu was born in 2008 with same symptoms as his late sister and doctors and parents believe their health problems are linked to the effects of Agent Orange. The couple have one healthy daughter who was born in 1995, before they started working at the airport, and she is now a university student. Photo: Damir Sagolj

The United States stopped spraying Agent Orange in 1971 and the war ended in 1975. Twenty years later, some people from villages and cities didn’t know all about it. Forty years later, today, children and their parents still suffer and a large part of the story remains untold. Agent Orange is one big tragedy made of many small tragedies, all man made.

There is not much I can do about it with my pictures except to retell the story, despite all the raised eyebrows. The pictures I took are not about the before and after, they are all about now. As for how poorly we read history and stories from the past, I’m afraid that is about our future, too.

Tang Thi Thang baths her disabled son Doan Van Quy outside their family home in Truc Ly, in Vietnam's Quang Binh Province April 11, 2015. Doan Van Quy's father, a soldier who served on 12.7 mm anti-aircraft guns during the Vietnam War, said he lived in several areas that were contaminated by Agent Orange. Two of his sons were born with serious health problems and the family and local health officials link their illnesses to their father's exposure to Agent Orange. Photo: Damir Sagolj

Dang Thi Quang and her son Nguyen Van Binh are reflected in an aquarium in their home in Vietnam's Quang Binh province April 11, 2015. Nguyen Van Binh’s father, a soldier who served in the Vietnamese army's transportation unit in the North, travelled and spent time in areas known as hotspots for Agent Orange contamination. Photo: Damir Sagolj 

Nguyen Thi Thiet (L) and Nguyen Thi Phuoc, who suffer from mental and physical illnesses, rest in their wheelchairs in their brother's house in Danang April 12, 2015. According to an official from the local Association for Victims of Agent Orange/Dioxin, their father was exposed to the Agent Orange while serving as a driver for the Vietnamese army in the South and his children's health conditions are linked to it. Photo: Damir Sagolj