However, exposure to ETS remains constant for the entire time spent in that room. Vaping does not generate sidestream vapour between puffs although some mainstream vapour is emitted when an e-cigarette user exhales. It is hard to measure the exposure of a passive smoker to environmental tobacco smoke.
The exposure varies according to the type and number of cigarettes or other tobacco products burned, the number of smokers present, the rate and manner of smoking, the room volume, the room ventilation rate, and the percentage of fresh or makeup air supplied.
Exposure to ETS has been estimated in terms of "cigarette equivalents". Cigarette equivalents can be measured by determining carboxyhemoglobin levels in blood. Carboxyhemoglobin is formed in the blood when someone inhales carbon monoxide. The hemoglobin in the blood that has oxygen bound to it is called oxyhemoglobin.
It is the oxyhemoglobin that carries oxygen to the tissues. However, carbon monoxide has a much stronger attraction to hemoglobin than oxygen. Thus, inhaled carbon monoxide quickly replaces the oxygen in the oxyhemoglobin and binds to the hemoglobin to form carboxyhemoglobin which can be measured.
Some studies use a urine test that measures the amount of cotinine in the body. Most of the nicotine absorbed by the body is broken down metabolized rapidly to form cotinine as the major by-product metabolite. Cotinine stays in the blood about 30 hours and reaches high concentrations in blood and urine.
Other studies can test for the level of nicotine in hair. Hair nicotine levels are a more accurate biomarker than urine cotinine. Various studies suggest that passive exposure to ETS over an eight-hour day is comparable to directly smoking one to three cigarettes. For example, it is thought that someone exposed to ETS will breathe in the same amount of the following contaminants as if they actively smoked one cigarette:. This finding shows that there is an association between certain diseases and exposure to ETS.
In more general terms, a risk of 1. When evidence from various studies is combined, they indicate that exposure to ETS increases the number of lung cancers detected in non-smokers.
Non-smoking co-workers of smokers have a relative risk of approximately 1. Traditionally, studies focused on finding the effects of ETS on the respiratory system.
More recently, studies show that exposure to ETS may increase the risk of cancer at sites other than the lung. While there have been fewer studies conducted, associations have been found with cancers such as cervical, bladder, nasal-sinus, and brain. In addition to the cancers mentioned for passive smokers, studies of active smokers have also recorded a risk of cancer to:. In addition, animal studies have seen cancers of the liver, pancreas, and aerodigestive tract head and neck, esophagus, and lungs.
It is known that active smoking is a cause of heart disease. It also increases the risk of having and dying from a stroke. Young children are most affected by SHS and least able to avoid it. Most of their exposure to SHS comes from adults parents or others smoking at home. Studies show that children whose parents smoke:.
Some of these problems might seem small, but they can add up quickly. Think of the expenses, doctor visits, medicines, lost school time, and often lost work time for the parent who must stay home with a sick child.
The Surgeon General has said that smoke-free workplace policies are the only way to prevent SHS exposure at work. Separating people who smoke from those who don't, cleaning the air, and ventilating the building cannot prevent exposure if people still smoke inside the building. An extra bonus of workplace smoking restrictions, other than protecting those who don't smoke, is that they may also encourage people who do to smoke less, or even quit.
Everyone can be exposed to SHS in public places where smoking is allowed, such as some restaurants, shopping centers, public transportation, parks, and schools.
Public places where children go are a special area of concern. Making your home smoke-free may be one of the most important things you can do for the health of your family. Any family member can develop health problems related to SHS. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads.
Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Mainstream smoke is the inhaled and exhaled smoke created while taking a puff on a lit cigarette.
It is one of two components in secondhand smoke. The second is sidestream smoke, which is the smoke that wafts off the end of a lit cigarette. There are plenty of cancer-causing chemicals in mainstream smoke. Some of them are:. The composition of mainstream smoke is affected by how the smoker inhales and exhales, so it will vary from person to person. The frequency of puffs, duration, and volume all contribute to the chemical makeup of mainstream smoke, as well. Sidestream smoke is more toxic than mainstream smoke for a couple of reasons that science has identified.
The machine-measured levels of compounds in mainstream smoke vary more between cigarette types than levels of compounds in sidestream smoke. Under similar smoking conditions i. Sidestream smoke compound levels do not vary greatly between different types of cigarettes and instead reflect the weight of the tobacco burned during smouldering.
Mainstream smoke differs from exhaled mainstream smoke as it undergoes some changes after being inhaled. The toxicity of secondhand smoke therefore depends on a variety of factors including the type of tobacco and other compounds in the cigarette, the proportion of burned tobacco producing mainstream and sidestream smoke, the volume and components of the air with which it mixes and the age of secondhand smoke.
Since most tobacco is smoked in the form of cigarettes, cigarettes are the major source of secondhand smoke. All types of smoked tobacco products, including cigars, pipes, waterpipes, kreteks and bidis, produce secondhand smoke. International Agency for Research on Cancer. Tobacco smoking. Health effects of exposure to environmental tobacco smoke: final report, approved at the Panel's June 24, meeting.
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