you smoke a cigarette from the filter end.
which end do you smoke a cigarette from?
the filter
cigarette makers traditionally lower the "tar" content of cigarettes by designing filters that allow air to mix with the smoke, diluting the smoke and all its constituents. the filters of most "low tar" cigarettes have rows of small ventilating holes encircling the filter which allow air to mix with smoke during inhalation, diluting the "tar" and nicotine in the smoke. the barclay cigarette, however, had four lengthwise channels which conducted the air from the ventilating holes directly into the smoker's mouth, preventing air from mixing with the smoke until the level of the smoker's mouth. the amount of air dilution in the barclay cigarette could be reduced if the smoker crushed the channels or blocked them with his lips. since the ftc machine did not block the channels, it allowed the maximum of amount of air to mix with the smoke.
barclay (cigarette)
the second method, as described by the iarc monographs, used to measure the carcinogenicity of cigarette smoke to animals is by exposing them to mainstream cigarette smoke. the iarc monographs define mainstream cigarette smoke as that which is emitted by the mouth end of the cigarette and therefore the smoke that human smokers would be exposed to most. the iarc monographs describe the methods and equipment that scientists have developed to make more effective and standardize the deliverance of mainstream cigarette smoke. these devices vary between whole-body and nose-only exposure, but typically involve machine smoked cigarette smoke being pumped into a small chamber that contains the animal test subjects. a variety of factors differentiate the experience of a human smoker from these animal test subjects'. human smokers inhale smoke voluntarily and therefore do so more deeply than do animal test subjects which typically adopt short, shallow breaths when exposed to smoke. the animal test subjects, primarily rodents and dogs, also have significantly morphologically different upper respiratory system from humans. despite these variables, the doses of smoke administered to these animals can be determined by examining tissue and blood samples. dogs, which cannot be exposed to cigarette smoke via inhalation chambers as easily as can small rodents, require different methods of cigarette smoke exposure. these methods include thracheostomy, in which smoke is pumped through a tube directly into a hole cut in the dog's throat, or through a mask fitted to the dog's face.
animals and tobacco smoke