AZUZ: Paula Claussen couldn't accept what she saw just outside Tijuana, Mexico. Lean-tos, where some people are living, were blown right over by high winds, rats, tarantulas and scorpions could walk right into some of the makeshift homes there.
This is according to Project Mercy, a nonprofit that Claussen founded in 1991. It's changing lives in the region one house at a time.
PAULA CLAUSSEN, CNN HERO: San Diego is one of the wealthiest cities in the States. But just right across the border, it's a different world.
In the outskirts of Tijuana, there is no running water, no sewage system. The floors are dirt and vermin crawl under the walls. It's hard for Americans to imagine.
Twenty-five years ago, I went to just donate clothes and I was shocked. I knew I had to do something to try to help them.
I started an organization that builds homes for people in need free of charge.
UNIDENTIFIED FEMALE (translated): It leaked everywhere.
CLAUSSEN: The water comes through.
UNIDENTIFIED FEMALE (translated): The house does not have a door. It's very unsafe. It's pretty difficult to live like this.
CLAUSSEN: This is so dangerous, all these wires.
In order to receive a house, we require that families work in the construction of a house with their neighbors.
Volunteers from California come down to build. They come away with a totally different attitude. It creates a bond.
We have developed a house that is sturdy, which can be built in one day.
UNIDENTIFIED FEMALE (translated): No more cold, no more rain. It's safer.
CLAUSSEN: These are our neighbors. To see the joy and the relief on their faces, that gives me the energy to continue.