Nicotine may react with hydroxyl radicals in ambient air, giving it a half life of approximately one day.Īn analysis of experiments funded by a tobacco company during the 1980s has shown that particulate matter in inhaled fresh sidestream smoke is three to four times as toxic per gram compared with mainstream cigarette smoke. Particles can coagulate, expand, condense, settle on surfaces, or evaporate, depending on concentration, ventilation, humidity, sunlight and other conditions (see section 4.3 Thirdhand smoke). Gaseous components can react with other pollutants and sunlight to form new chemicals. Over time, secondhand smoke changes in nature. Classified as ‘semi-volatile’, their ability to change form according to environmental conditions means that they remain detectable in the indoor environment for longer periods after active smoking has ceased. Many constituents, such as nicotine and some PAHs, exist in both the gaseous and the particulate phase of secondhand smoke. Research shows that about half the particulate matter from secondhand smoke is still airborne after five to six hours. Secondhand smoke can be detected in the indoor environment well after it has been generated. 6 Short and long-term exposure to fine particulate matter contributes to the aggravation of asthma and other respiratory diseases, lung and other cancers, cardiovascular disease and death. They are smaller than the particles in mainstream smoke and can penetrate deeper into the lungs, resulting in higher toxicity through oxidative stress and inflammation. Most particulate matter in secondhand smoke is in the submicron (< 1µm diameter) range, meaning that it is classified as fine particulate matter (also referred to as respirable suspended particles). A number of carcinogenic heavy metals, and weaker carcinogens that induce tumours in a variety of organs, are also present in the particulate matter. 5 PAHs and nitrosamines induce tumours in the respiratory tract and the lung, while the aromatic amines cause bladder cancer. The metabolites of NNK are detectable in the urine of non-smokers exposed to secondhand smoke. The most studied of these include polycyclic aromatic hydrocarbons (PAHs) including benzo(a)pyrene, aromatic amines 2-naphthylamine and 4-aminobiphenyl, and the tobacco-specific nitrosamines N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino-)1-(3,pyridyl)-1-butone (NNK). 4 Particulate matter refers to microscopic solid and liquid matter suspended in air, which can be inhaled, and if small enough enter your bloodstream, causing serious health problems. In addition to these chemicals, secondhand smoke contains particulate matter which is an independent health hazard. The California Environmental Protection Agency has identified other carcinogenic and toxic constituents including acrolein, formaldehyde, carbonyl sulphide, hydrazine, pyridine, styrene and toluene. Vapour phase constituents affect the central nervous system, the immune system, the heart and the liver, and cause eye, skin and respiratory problems. Secondhand smoke also contains 50 known carcinogens including benzene. Two of these constituents are carbon monoxide, which reduces the oxygen-carrying capacity of blood, and nitrogen oxides, which affect respiratory function. Secondhand smoke contains more than 4,000 chemical compounds, including at least 250 constituents that are toxic to the central nervous system, immune system, the heart and the liver and cause eye, skin and respiratory problems. Secondhand smoke is a complex mixture of chemical compounds and particulate matter that are damaging to human health. Unless otherwise noted, the following section is compiled from reviews published by the International Agency for Research on Cancer (2004), 1 California Environmental Protection Agency (2005) 2 and the Office of the US Surgeon General (2006). 4.2 What is in secondhand smoke? In Scollo, MM and Winstanley, MH. Suggested citation: Campbell, MA, Ford, C, & Winstanley, MH.
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