Betty’s home stands on the edge of a striking red cliff. Her family built the home from materials in their environment generations ago and passed it along from mothers to daughters. But it is cold, and the home is small with few windows. Insufficiently ventilated homes in these areas can have high levels of particulate matter, dust, mold and radon, a naturally occurring gas that can cause lung cancer. Rosa, a great-grandmother, lives in her family home with a large wood-burning stove. On one wall are colorful paintings representing her clan lineage. On another wall, black stains show where an exhaust vent was improperly installed.