WASHINGTON -- Smoking soon could be banned in public housing nationwide -- even inside people's apartments.

The Department of Housing and Urban Development proposed a rule Thursday that would require the more than 3,100 public housing agencies across the country to make their properties smoke-free.

"We have a responsibility to protect public-housing residents from the harmful effects of secondhand smoke -- especially the elderly and children who suffer from asthma and other respiratory diseases," HUD Secretary Julian Castro said in a statement.

Castro said the ban would protect the health of more than 760,000 children and save about $153 million a year in health-care costs, repairs and preventable fires.

The rule would ban lit tobacco products -- cigarettes, cigars or pipes -- in all residences, indoor common areas and administrative offices. Smoking also would be prohibited outdoors within 25 feet of housing and administrative buildings. Electronic cigarettes that emit vapor but not smoke would not be subject to the ban.

In 2009, HUD began encouraging public housing agencies nationwide to adopt smoke-free policies.

Currently, there are more than 228,000 public housing units that have gone smoke-free, including in Boston, Seattle, Minneapolis, San Antonio and Detroit.

The proposed rule would affect the more than 940,000 units where smoking is allowed.

Anti-smoking advocates praised HUD's move, stressing the dangers of secondhand smoke.

But Jamila Michener, an assistant professor of government at Cornell University, worries enforcing the ban could lead to lead to evictions.

"This is a misdirection of energy," Michener said. "What HUD should be focusing on is getting people in those housing projects enrolled in Medicaid, and that would give them access to smoking-cessation services, which would actually directly address the public-health issue of concern here."