CHICAGO -- There's a new way to fight rat populations in Chicago -- and it doesn't require any poison.
The city is using dry ice to kill rats.
At the end of August, sanitation crews started putting dry ice into rat burrows and sealing up the holes with dirt and newspaper.
As the dry ice warms into a gas, it suffocates the trapped rats and leaves them to decompose in the holes.
USA Today reports dry ice is cheaper, more effective and safer than traditional poison, which has the potential to harm small pets and birds.
The new method comes as rat complaints in the city are up nearly 50 percent this year.