No day is the same for Evalyne Nyangweso, entrepreneur and owner of an ambulance service dedicated to an unforgiving community prone to poor health, disease and high crime rates.

Operating in Kibera, Africa’s largest slum, where traditional ambulances daren’t go and even police tread carefully, Nyangweso and her crew are the first responders to medical emergencies.

Q&A Why are we reporting on Kibera? Show More than 60% of all African city dwellers live in slums. As the climate crisis continues to drive people away from rural areas and into cities, urbanisation has become a growing issue across the globe. The Guardian's Global development team travelled to Africa's biggest slum, Kibera, in Nairobi, Kenya, in an effort to look beyond the stereotypes and myths of life in a slum. Many people living in Kibera work hard, long days. They pay high rents for flimsy shacks on land owned by the government and effectively squatted on by landlords. They have no services and the only taxation comes in the form of protection money demanded by police and gangs. Each day is a struggle to scrape together enough money and food to reach the next. Electricity, clean water, toilets, healthcare and schools are either non-existent or not available to all residents. At any one time, 50% of Kibera's 15- to 25-year-old women are pregnant. Abortion is illegal and contraception scarce. Rape and child sex abuse is endemic. Abuse of drink and drugs is rife. Food is cheap but unhealthy – fizzy drinks are easier to get than clean water.

From domestic violence to gang rape, rapid response paramedics encounter extremes. Punctuality and compassion are key, and failure can result in being pelted with stones by frustrated bystanders. It’s not a job for the faint-hearted – homes in Kibera are constructed of timber stakes, mud walls and corrugated steel roofs and are built on animal and human waste. Cholera and typhoid are rife. HIV/AIDS affects 11.5-14% of the adult population, and only 60% of those infected are aware they have the disease.

Evalyne Nyangweso, founder of Rapid Response Paramedics, is proud of her ambulances. Photograph: Rod Austin/The Guardian

Despite this, Nyangweso remains dedicated and on call 24/7 to 250,000 of Kenya’s poorest people. In the little spare time she has, she advertises, handing out calling cards in hospitals and churches and posting stickers around Kibera.

Rapid Response is now in its third year. Nyangweso came up with the idea after she was made redundant from Nairobi’s St Mary’s Mission hospital.

Nyangweso and her husband are both trained nurses, with children aged nine, 14 and 19, for whom they have high hopes. “It’s a medical family. I like it and would like them to be in the same field. If not the ambulance [service], maybe doctors or surgeons,” she says.

She knew the Red Cross were struggling to cope with demand in Kibera. After completing a paramedic course, she bought a fully equipped ambulance and a second compact vehicle to negotiate the narrow dirt tracks. Both were second-hand. Next she recruited staff: Timon and George, trained emergency vehicle drivers, and Winnie, a Red Cross-trained paramedic.

The next challenge was communication. With no hi-tech call centre, Nyangweso uses her own mobile, juggling business and personal calls. She hopes one day she will make enough money for a second phone, as her current one has a broken screen.

Evalyne Nyangweso briefs her team of first responders. Photograph: Rod Austin/The Guardian

“We collected a pregnant woman from Kibera and delivered her to hospital, but her child died. She had no phone and wanted to ring her husband to ask him to take the child to the mortuary, as the hospital won’t do this without payment. I lent her my phone. Carried away by emotions, she threw it, damaging the screen. She had no money to pay for it or the ambulance journey. It’s difficult when people live below the poverty line. There was nothing I could do,” she says.

Kenya’s health service is not free and the briefest contact with a medical practitioner is met with a demand for payment. “With most clients we simply agree a figure. Within Nairobi we’re supposed to charge 5,000 shillings [£38.90] for each trip. In Kibera, they cannot afford that, so I charge between 3,000 and 3,500 shillings depending on the strength of their family. We won’t refuse someone in need because they don’t have money.

“Some patients don’t pay. They promise and don’t honour it,” she says. “One woman had her baby prematurely, the baby needed to be taken to intensive care. She had no money but said she would pay the next day, so we took them. Unfortunately, the baby passed away. The next day I rang the woman who asked: ‘Why are you calling? Why do you want me to pay when my baby is no more?’ – so she didn’t pay. That is life in Kibera. If the result is not good, they do not care.”

The liveried vehicles sit on standby in Nairobi’s Uhuru Gardens car park from 8am to 6pm, six days a week and staff are on call throughout the night. Nyangweso monitors response times; drivers must be at their vehicle within five minutes of a call and ambulances must arrive at the scene within 20 minutes, even through the dark streets of Kibera where road accidents, muggings, assaults, and shuttle runs between hospitals are commonplace.

Quick Guide Kibera in numbers Show - Estimates of how many people live in Kibera range from 250,000 to 1 million. - Life expectancy is 30 years. - The biggest killers come from diet and dirt. Diabetes is rife from cheap, high-sugar food. - One in four children attends school. - One toilet block serves approximately 50 shacks, with each shack housing roughly eight people.

“Conditions in Kibera are not easy. It’s overpopulated, with no discipline. It’s every man for himself, which makes our work difficult,” says Nyangweso. “Problems occur during disputes. You’re there to take one party to hospital but the other side does not want you to, so they start pulling you about. We’ve never been attacked but I know of cases where ambulances have arrived late and the patient had deteriorated. The crowd became angry and beat the crew brutally.”

Children play by a river choked with plastic and human waste that runs alongside the houses in the centre of Kibera. Photograph: Kate Holt/The Guardian

Nyangweso’s primary concern is for women. “Life is hard for women. I don’t know why they have so many children, when both parents are not working. The men are idle, drinking alcohol all day, it’s up to women to fetch food for the family. When they get home their men take their money to buy more drink. There will be a quarrel – he’s drunk, feels inferior and unable to provide for the family. That’s why there are a lot of rapes and domestic violence. It’s brutal, men use sticks, pangas (machetes) and knives on women. Neighbours call us, and often we cannot stop the bleeding, we can only wrap the injury and stretcher the woman to hospital,” says Nyangweso.

Kibera has a prolific rape crisis. Perpetrators target the young, the elderly and those with disabilities. “Incidents of rape are high at any time of the day. Girls aged 9–15 being raped by middle-aged men is most common,” she says.

Men drink home brewed alcohol through straws in a bar in Kibera. Photograph: Kate Holt/The Guardian

“Victims often run away, so it comes down to the parents to follow up the case. If they don’t, the police take no action. If the girl comes from a poor family and the boy a well-off one, corruption gets involved and the case is ignored. Unless you find them or they are held by a parent until we arrive, it is difficult, as they run, especially teenagers,” says Nyangweso.

“Yesterday we attended a call to a young girl who had had sex with man with HIV. We don’t know whether it was with consent or rape as she ran away. Here after 24 hours or a bath you cannot prove it was rape. We spent the day searching for her then gave up.”

If rape is suspected the paramedics have to stop at Kibera’s police station to report it before going to hospital. “At the police station they check outer clothing for signs of assault or semen. Only if they agree it’s rape – [then] we take the victim to hospital. If the family give consent the hospital will go through the examination process but up until recently it was not free, they had to pay. Likewise for DNA tests, but this changed recently. Sometimes having to pay is a problem, so maybe they leave it, treat the victim and go back home. Then later you hear that the father or husband of the raped woman has fought the suspect and a grudge builds between the two families.”

A significant number of the guilty go unpunished. “It’s bad, imagine as a parent, having a girl of 15 and a man who knows he has a disease goes with her. A girl whom you as a parent are trying to bring up to be somebody in society. Then he does something like that and goes unpunished. It hurts.”

Prostitution is rife in Kibera, including among the very young, says Nyangweso. “They do it to help their mothers … mothers send them to do it, saying: ‘Bring money so I can feed your younger brothers and sisters,’” she says. Women are also trapped into having sex with other men to feed their children, says Nyangweso.

She says the government must be stronger on rape, prostitution and violence against women “because that is the beginning of the family. Without rights there is no future.”

She adds that the government should create jobs for Kibera’s men. “Many are idle, drinking cheap brews, causing indiscipline and shortening their lives – but I think they simply don’t care. [They think:] ‘I will never be a victim because I can [punch] somebody. I cannot allow it to happen, I’m capable.’ These things happen to women in Kibera because they are not independent, but I can live my own life with my children and if my husband starts, I can tell him to leave. I am independent.”