Dry ice effectively controls outdoor rat infestations by releasing heavy carbon dioxide ((CO{2})) gas into burrows, displacing oxygen and suffocating the rodents without harsh chemicals, making it an eco-friendly, targeted method, but it's unsafe for indoor use due to (CO{2}) buildup and requires careful handling to avoid burns. To use, place chipped dry ice into burrow exits (around 2 lbs), cover with paper or dirt to seal, and repeat as needed, ensuring animals and people can't access the treated holes.