Pathophysiology

A 2004 study by the International Agency for Research on Cancer of the World Health Organization concluded that non-smokers are exposed to the same carcinogens as active smokers. Sidestream smoke contains more than 4,000 chemicals, including 69 known carcinogens. Of special concern are polynuclear aromatic hydrocarbons, tobacco-specific N-nitrosamines, and aromatic amines, such as 4-aminobiphenyl, all known to be highly carcinogenic. Mainstream smoke, sidestream smoke, and second-hand smoke contain largely the same components, however the concentration varies depending on type of smoke. Several well-established carcinogens have been shown by the tobacco companies' own research to be present at higher concentrations in sidestream smoke than in mainstream smoke.[84] Second-hand smoke has been shown to produce more particulate-matter (PM) pollution than an idling low-emission diesel engine. In an experiment conducted by the Italian National Cancer Institute, three cigarettes were left smoldering, one after the other, in a 60 m? garage with a limited air exchange. The cigarettes produced PM pollution exceeding outdoor limits, as well as PM concentrations up to 10-fold that of the idling engine.[85] Tobacco smoke exposure has immediate and substantial effects on blood and blood vessels in a way that increases the risk of a heart attack, particularly in people already at risk.[86] Exposure to tobacco smoke for 30 minutes significantly reduces coronary flow velocity reserve in healthy nonsmokers.[87] Pulmonary emphysema can be induced in rats through acute exposure to sidestream tobacco smoke (30 cigarettes per day) over a period of 45 days.[88] Degranulation of mast cells contributing to lung damage has also been observed.[89] The term "third-hand smoke" was recently coined to identify the residual tobacco smoke contamination that remains after the cigarette is extinguished and second-hand smoke has cleared from the air.[90][91][92] Preliminary research suggests that by-products of third-hand smoke may pose a health risk,[93] though the magnitude of risk, if any, remains unknown. In October 2011, it was reported that Christus St. Frances Cabrini Hospital in Alexandria, Louisiana would seek to eliminate third-hand smoke beginning in July 2012, and that empl

yees whose clothing smelled of smoke would not be allowed to work. This prohibition was enacted because third-hand smoke poses a special danger for the developing brains of infants and small children.[94] In 2008, there were more than 161,000 deaths attributed to lung cancer in the United States. Of these deaths, an estimated 10% to 15% were caused by factors other than first-hand smoking; equivalent to 16,000 to 24,000 deaths annually. Slightly more than half of the lung cancer deaths caused by factors other than first-hand smoking were found in nonsmokers. Lung cancer in non-smokers may well be considered one of the most common cancer mortalities in the United States. Clinical epidemiology of lung cancer has linked the primary factors closely tied to lung cancer in non-smokers as exposure to second-hand tobacco smoke, carcinogens including radon, and other indoor air pollutants. Sidestream smoke is smoke which goes into the air directly from a burning cigarette, cigar, or smoking pipe. Sidestream smoke is the main component of Second-hand smoke (SHS), also known as Environmental Tobacco Smoke (ETS) or passive smoking The chemical constituents of sidestream smoke are different from those of directly inhaled ("mainstream") smoke. Sidestream smoking has been classified as a Class A carcinogen by the U.S. Environmental Protection Agency. Sidestream tobacco smoke is made up of many components. Some of the constituents of which are carbon monoxide, tar, nicotine, ammonia, benzene, cadmium and 4-aminobiphenyl. Some of the other compounds found in sidestream smoke are: vinylchloride, hydrogen cyanide, arsenic, acrolein, acetaldehyde, formaldehyde, catechol, cresol, hydroquinone, lead, methyl ethyl ketone, nitric oxide, phenol, styrene, toluene, and butane. Exposure to sidestream smoke yields higher concentrations of these compounds as well as increased concentrations of carboxyhemoglobin, nicotine, and cotinine in the blood. When comparing sidestream and mainstream condensate, side stream has 26 times more condensate per gram than mainstream smoke. Due to the incomplete combustion process responsible for the creation of sidestream smoke, there may be exposure to higher concentrations of carcinogens than are typically inhaled directly.