Low-yield cigarettes and diminution of small airways lung function in long-term smokers

现代香烟被设计成当香烟中的烟草燃烧时产生低焦油量。焦油含有人类致癌物质，长期以来，监测和调节焦油产量一直是澳大利亚全面烟草控制战略的一部分。这种对焦油的关注含蓄地认可了低产量卷烟是一种更安全的卷烟。然而，最近出现了关于吸低产量香烟是否减少了吸烟危害的争议。令人担忧的是，肺腺癌，一种最常见于外周小气道的肺癌，发生频率有所增加。这可能是因为低产量香烟，尼古丁和焦油产量减少，吸烟者吸烟更强烈，以弥补低尼古丁。我们所说的吸烟更强烈，是指更大更频繁地吸烟，将烟雾深深地吸入肺部，并在呼气前屏住呼吸。这种吸烟方法会导致更多的焦油颗粒沉积在肺的周围，腺癌是最常见的。由于吸烟也与肺小气道的其他结构变化有关，导致气流阻塞，我们将测试吸低产量香烟是否比吸高产量香烟更容易阻塞小气道。为了测试机制是否是吸烟的方法，我们将仔细描述和量化每个受试者的吸烟模式，包括烟雾样Technegas颗粒在外周肺中的沉积。

The modern cigarette has been designed to produce low yields of tar when the tobacco in the cigarette is burnt. The tar contains human carcinogens, and monitoring and regulating yields of tar has long been part of the comprehensive tobacco control strategy in Australia. This focus on tar has given an implicit endorsement of the low-yield cigarette as a safer cigarette. Recently, however, controversy has emerged about whether smoking low-yield cigarettes has reduced the harm done by smoking. The concern is that adenocarcinoma of the lung, a type of lung cancer that is most common in the small peripheral airways, has increased in frequency. This could be because the low-yield cigarette, with reduced yields of nicotine as well as tar, is smoked more intensely by smokers to compensate for the low nicotine. By smoking more intensely, we mean taking larger and more frequent puffs, inhaling the smoke deeply into the lungs, and holding the breath before expiring. This method of smoking would result in more tar particles being deposited in the peripheries of the lung where adenocarcinoma is most common. Because cigarette smoking has been linked also with other structural changes in the small airways of the lung, resulting in obstruction of airflow, we will test whether smoking low-yield cigarettes is associated with greater obstruction of the small airways than is smoking higher-yield cigarettes. To test whether the mechanism is the method of smoking, we will carefully describe and quantify each subject's pattern of smoking including the deposition of smoke-like Technegas particles in the peripheral lung.