I want my air ducts cleaned, is it my responsibility or my landlords?

My air-ducts are rusting in 2 places for sure. They are also very nasty. I just vacuumed a bunch of dust out of the parts my vacuum hose can reach. Sometimes I see particles coming up out of my ducts. My townhouse is about 15 yrs old. I'ld like cleaner air ducts. Should I ask my landlord?