HOUSTON (AP) — The danger isn’t over yet for Harvey evacuees who are returning to flood-ravaged homes where they face the threat of mold, spoiled food, gas leaks and downed power lines.

While some residents of the still-flooded western part of Houston may not be able to return home for days, others are starting a massive cleanup and dragging sodden debris to the curbside. Keeping them safe is a concern of health officials who hope to reach them through Twitter, Facebook and Instagram.

U.S. Health and Human Services Department spokeswoman Joni Geels says some evacuees have been able to keep their phones charged at charging stations in the George R. Brown Convention Center in Houston. She says cellular “service has been really good,” which has helped with communicating safety advice.