More than a billion people around the world live in houses that have dirt floors. They deal with dust clouds that form when they sweep the floor. Rain can bring mud and insects. And fecal matter, human and animal, is a huge public health threat to children.

But it’s one of those problems that hasn’t got as much attention as it deserves, even in programs to address poverty – because it’s part of what researchers call multidimensional poverty. “Of the 1.6 billion people living in multidimensional poverty,” says University of Oxford research, “more than 1.2 billion don’t have adequate sanitation, over 1 billion are living on dirt floors, around 900 million don’t have electricity, about 900 million live in a household where someone is malnourished, and more than half a billion live in a home where no one has completed five years of schooling.”

So you can understand why fixing dirt floors might not seem to be at the top of the agenda for addressing this complicated poverty.