<unk> , besides being an irritant and significant indoor air pollutant, is known to cause lung cancer, heart disease, chronic obstructive pulmonary disease (COPD), emphysema, and other serious diseases in smokers (and in non-smokers as well). The actual mechanisms by which smoking can cause so many diseases remain largely unknown. Many attempts have been made to produce lung cancer in animals exposed to<unk>  by the inhalation route, without success. It is only by collecting the "tar" and repeatedly painting this on to mice that tumors are produced, and these tumors are very different from those tumors exhibited by smokers.<unk>  is associated with an increased risk of developing respiratory conditions such as bronchitis, pneumonia, and asthma.<unk>  aerosols generated at temperatures below 400 ℃ did not test positive in the Ames assay. In spite of all changes in cigarette design and manufacturing since the 1960s, the use of filters and "light" cigarettes has neither decreased the nicotine intake per cigarette, nor has it lowered the incidence of lung cancers (NCI, 2001; IARC 83, 2004; U.S. Surgeon General, 2004). The shift over the years from higher- to lower-yield cigarettes may explain the change in the pathology of lung cancer. That is, the percentage of lung cancers that are adenocarcinomas has increased, while the percentage of squamous cell cancers has decreased. The change in tumor type is believed to reflect the higher nitrosamine delivery of lower-yield cigarettes and the increased depth or volume of inhalation of lower-yield cigarettes to compensate for lower level concentrations of nicotine in the smoke. In the United States, lung cancer incidence and mortality rates are particularly high among African American men. Lung cancer tends to be most common in developed countries, particularly in North America and Europe, and less common in developing countries, particularly in Africa and South America.
Tobacco smoke
Third-hand smoke
Cigarette
Heated tobacco product
Smokeless tobacco
Air pollution
Cigarette Burns
Persistent organic pollutant