based on the 'as low as reasonably practicable' principle". some hospitality organisations have claimed that ventilation systems could bring venues into line with smoke-free restaurant ordinances. a study published by the american society of heating, refrigerating and air-conditioning engineers and funded by the robert wood johnson foundation found one establishment with lower air quality in the non-smoking section, due to improperly installed ventilation systems. they also determined that even properly functioning systems "are not substitutes for smoking bans in controlling environmental smoke exposure". the tobacco industry has focused on proposing ventilation as an alternative to smoke-free laws, though this approach has not been widely adopted in the u.s. because "in the end, it is simpler, cheaper, and healthier to end smoking". the italian smoke-free law permits dedicated smoking rooms with automatic doors and smoke extractors. nevertheless, few italian establishments are creating smoking rooms due to the additional cost. a landmark report from the u.s. surgeon general found that even the use of elaborate ventilation systems and smoking rooms fail to provide protection from the health hazards of secondhand smoke, since there is "no safe level of secondhand smoke". preemption a number of states in the united states have "preemption clauses" within state law which block local communities from passing smoke-free ordinances more strict than the state laws on the books. the rationale is to prevent local communities from passing smoke-free ordinances which are viewed as excessive by that state's legislature. other states have "anti-preemption clauses" that allow local communities to pass smoking ban ordinances that their legislature found unacceptable.