The idea of living on a floor made of dirt may seem completely alien to you, but for more than a billion people in the world, living in homes with dirt floors is the norm. And that’s a problem.

Dirt floors are unsanitary and can make people sick, often playing host to bugs such as termites and worms. They’re also difficult to clean should anything unhygienic spill on them. Stanford alum Gayatri Datar has been well aware of this problem since she graduated in 2014. Since then, she’s been pursuing a rather unorthodox goal: rid the world of dirt floors.

That’s why she created a start-up nonprofit called EarthEnable, which sells low-cost floors made from locally sourced clay, pebbles, and sand, which are then sealed with a proprietary eco-friendly varnish. A home with a hard floor is far better for the people living in them, as a floor can be readily cleaned reduces the number of pathogens and germs they’re exposed to. The cost a floor for one home is about $70, far less than the cost of concrete.

Although EarthEnable struggled at first to source quality materials, now they’re faring much better. More than 4,400 earthen floors have been installed in Rwanda, and the startup is working closely with Rwandan government officials who say they too want to eliminate dirt floors. Now the goal is to move beyond to bring hard floors to more homes around the world.