Secondhand smoke causes early death and disease in children and in adults who do not smoke. The more secondhand smoke to which you are exposed, the higher your risk of disease. There is no level of exposure to secondhand smoke that is free of risk.
Reviews of the research conclude that secondhand smoke causes the following diseases and conditions:
- Heart disease
- Lung cancer
- Irritation of the eyes and nose
In children and infants
- Sudden infant death syndrome (SIDS or cot death)
- Lower birthweight (where the pregnant mother was exposed to SHS)
- Bronchitis, pneumonia and other lung/airways infections
- Wheeze illnesses in early childhood
- Middle ear disease (otitis media or ‘glue ear', middle ear effusion)
- Respiratory symptoms including cough, phlegm, wheeze and breathlessness
- Higher rates and worsening of asthma
- Lower level of lung function during childhood (i.e. they cannot breathe in as deeply or breathe out as hard as they would otherwise)
Research also links exposure to secondhand smoke to other diseases and conditions. They include:
- Nasal sinus cancer
- Breast cancer
- Atherosclerosis (disease of the blood vessels)
- Acute (short term) respiratory symptoms including cough, wheeze, chest tightness and difficulty breathing among both healthy persons and persons with asthma
- Chronic (long term) respiratory symptoms
- Acute (short term) decline in lung function in persons with asthma
- Small loss of lung function
- Development of asthma and worsening of asthma control
- Chronic obstructive pulmonary disease (COPD)
In children and infants
- Development of asthma
- Preterm delivery (where the pregnant mother was exposed to SHS)
- Childhood cancers: leukemias, brain cancer and lymphomas (where both the pregnant mother and the child after birth were exposed to SHS)
- Lung complications during and after surgery
- Worsening of cystic fibrosis4
- Meningococcal disease
Secondhand smoke increases the risk of coronary heart disease in nonsmokers. Nonsmokers with long term exposure to tobacco smoking in their home have an estimated 25% to 30% increased risk of heart disease compared to non-exposed nonsmokers. This increased risk of heart disease from SHS is about one-third the increased risk of active smoking. Low levels of tobacco smoke appear to have a strong effect on heart disease risk, but the risk tends to level off at the higher exposures of smoke incurred by active smokers. Levels of chemicals known to play a role in heart disease are higher in sidestream smoke than in the mainstream smoke inhaled by smokers. Research also indicates that non-smokers are more sensitive to certain effects of SHS than active smokers.
Secondhand smoke interferes with the normal workings of the heart, blood and blood vessels, causing both short and long term damage. Some effects occur within as little as 30 minutes, and appear to be nearly as large as those seen in an active smoker. For example, secondhand smoke affects the lining of your blood vessel walls and interferes with the way they regulate blood flow. It makes your blood thicker, stickier and more likely to clot. Carbon monoxide from SHS replaces some of the oxygen in your blood, reducing the delivery of oxygen to your heart and muscles. With less oxygen, short-term or permanent damage to your heart and tissues is more likely. Over many years, the damaging effects of secondhand smoke help to build up fatty deposits on blood vessel walls, narrowing and stiffening them, and causing inflammation. Eventually this may lead to heart attack.
The majority of deaths from secondhand smoke are from heart disease. People with other risk factors for heart disease such as diabetes, high blood pressure, and vascular disease are at even greater risk from SHS exposure.
Secondhand smoke has been confirmed as a cause of cancer in humans.
Secondhand smoke is a cause of lung cancer in non-smokers. Non-smokers with long term exposure to tobacco smoke have an estimated 20% to 30% higher risk of developing lung cancer than non-exposed nonsmokers.
The evidence suggests that secondhand smoke may be a cause of nasal sinus cancer and breast cancer in younger women (before menopause), but more research is needed before these findings can be confirmed. Breast cancer is the most common cancer and the leading cause of cancer death among Australian women.
Impact on the health of workers
Studies in both workplace and restaurant settings confirm that only those policies that require establishments to be totally smokefree adequately protect non-smokers from exposure to SHS. In March 2006, most indoor Victorian workplaces became smokefree. On July 1st 2007, smoking was banned in enclosed indoor premises with liquor licenses including pubs, bars and nightclubs. The "high-roller" rooms at Crown Casino remain the last places in Victoria where indoor workers in licensed premises are exposed to SHS.
Previously, Victorian hospitality workers were more likely to work in smoky areas that tended to have higher levels of tobacco smoke than other workplaces. As a result, they were more likely to suffer from health problems such as wheezing, coughing, sore eyes and sore throats. Importantly, research also shows that when smoking is banned in indoor venues, the health of bar staff improves, even in smokers.
Smoking is still allowed in outdoor dining and drinking or ‘al fresco' areas. The legislation allows for these areas to have a roof and up to 75% of the wallspace to be enclosed. It remains to be seen if SHS continues to be a problem at these venues.