All states have laws (statutes) that require landlords to install and maintain smoke detectors in leased residential premises (apartments, homes).

Some states such as Iowa, Maine, Massachusetts, Ohio, and Vermont require photoelectric or ionization sensors—at least in new construction. And Oregon requires smoke detectors with a HUSH mechanism that allows the alarm to be silenced or temporarily desensitized for 7 minutes while a known condition such as cooking is causing the alarm to activate.

Most states also require landlords to install and maintain carbon monoxide detectors in leased residential premises. Smoke and carbon monoxide detectors are widely available in the same device.

In Missouri, landlords are required by law to install and maintain smoke detectors in leased residential premises. The Missouri Revised Statutes, specifically Section 67.300, mandates that all dwellings must have a functional smoke detector. The law applies to both new construction and existing residential buildings. While Missouri law does not specify the type of smoke detector (such as photoelectric or ionization sensors), it does require that the devices be maintained in good working order. Additionally, Missouri law requires the installation and maintenance of carbon monoxide detectors in residential rental properties. This is outlined in Section 70.220 of the Missouri Revised Statutes, which states that any dwelling unit that contains a fuel-burning appliance, a fireplace, or an attached garage must have a functional carbon monoxide alarm. Landlords are responsible for the installation of these detectors and for ensuring they are operable at the beginning of each tenancy. Tenants are typically responsible for testing the detectors regularly and replacing batteries as needed during their tenancy.