"Regardless of whether it is affirmatively stated in the lease, a landlord is required to provide for its tenants quiet enjoyment. Examples of nuisances which violate this covenant of quiet enjoyment and interfere with the comfort, convenience, or health of an occupant are: foul odors; noxious gases; smoke; dust; loud noises; excessive light; and high temperatures. To some tenants, this may mean their right to live in their unit without suffering the daily intake of their neighbor's second hand marijuana smoke. However, the toking tenant would likely argue that their right to enjoy their unit includes the right to smoke marijuana.
This is clearly a balancing act between tenants since violating the right of one can lead to liability for a breach of the other's right to quiet enjoyment. One consideration is whether multiple tenants are bothered. If multiple tenants are bothered, the landlord will have a stronger argument that the marijuana smoke constitutes a nuisance. If only one tenant is bothered, the landlord must suffer the balancing act and determine which tenant they would rather protect and which tenant they would rather risk being liable to."