Yousuf and his family left their home in eastern Afghanistan eight years ago.They went to the city of Kabul to escape war, but they could not escape sadness.Five of Yousuf's children died in the Afghan capital, not from violence, but from air pollution.One by one, each child developed a chest infection and other health problems from the pollution.The children never made it to age seven, Yousuf told The Associated Press.The 60-year-old has nine surviving children.There are no official numbers on how many Afghans die of pollution-related disorders.But the research group State of Global Air said that in 2017,more than 26,000 deaths could be linked to air pollution.In comparison, 3,483 civilians were killed that year in the Afghan war, the United Nations reports.Kabul has become one of the most polluted cities in the world.It rates at the top of the list among other polluted capitals such as India's New Delhi or Beijing, China.Kabul is home to about 6 million people.On many days, a mix of smog and smoke lies over the city.In some cases, families burn whatever they can to keep warm in cold weather.The air in their own homes then poisons them.Household pollution was partly to blame for at least 19,400of Kabul's deaths in 2017, the State of Global Air study found.Yousuf lives in a camp that is home to more than a hundred families."We are so poor, and we have lots of problems...My children collect garbage from dump yardsand we use it for cooking and heating to keep the kids warm," he said.Many years of war have worsened the damage to Afghanistan's environment.Environmental issues are less importantfor a government struggling with security issues and a sinking economy.Thirty or 40 years ago, "it was a wish for people to come to Kabul and breath this air,"said Ezatullah Sediqi, deputy director for the National Environmental Protection Agency, or NEPA.But in the wars since, "we lost all our urban infrastructure for water,electricity, public transportation, green areas, all these things," he said.Kabul's environmental department has launched a programto control old vehicles, one major source of pollution."Fighting pollution is as important as fighting terrorism,"said Mohammad Kazim Humayoun, the department's director.Afghan officials warn that this winter will likely be colder than usual.At Kabul's Indira Gandhi Children's Hospital, doctors saythey have seen the numbers of patients with pollution-related health problems increase.Saifullah Abassin, a specialist trainer at the hospital,said his hospital ward has a capacity of 10 patients but often has three times that number.The government has launched an environmental awareness campaign.City officials have also called on people to stop burning garbage for heat and instead use fuel.But there are other steps officials need to take,such as enacting a plan to stop unplanned development and creating more green spaces.Sediqi, of the NEPA, said that ever since the first post-Taliban governmentwas created in 2001, there was no planning on urban infrastructure."Unfortunately, that led to unplanned development," he said."So now we have numerous urban problems and challengesand organizational challenges, which is causing the environmental pollution."