World No Tobacco Day: Understanding the hidden dangers of passive smoking

World No Tobacco Day, observed on May 31st, raises awareness about the dangers of tobacco use and its impact on health. This includes the often overlooked threat of secondhand smoke, also known as passive smoking. Inhaling this invisible cloud of chemicals from someone else's cigarette can significantly increase your risk of developing chronic obstructive pulmonary disease (COPD), a serious lung condition. "Passive smoking is a significant risk factor for the development and progression of COPD, exerting harmful effects on the respiratory system through inflammation, airway obstruction, and oxidative stress.

Epidemiological evidence supports a clear association between passive smoking and COPD, with vulnerable populations at increased risk of adverse outcomes," shares Dr. Suhas H S, consultant pulmonologist at Manipal Hospital, Bengaluru. On World No Tobacco Day, he delves into the impact of passive smoking on our lung health, and shares preventive measures.

What is Chronic Obstructive Pulmonary Disease?
Suhas H S: COPD is characterised by irreversible damage to the airway and lung parenchyma caused predominantly by exposure to toxic fumes, with smoking being the most common source. It poses a serious public health problem and imposes a huge financial burden on healthcare worldwide. COPD is reported as the third leading cause of death and the fifth cause of life years lost globally due to respiratory failure and serious complications. A large population-based survey in India showed an overall COPD prevalence of 4.4 per cent in people over 40, while a study in the United States indicated a higher prevalence among people over 65. Unfortunately, as the population ages, with more than 21 per cent projected to be over 60 years of age by 2050, the issue of COPD is expected to receive more attention and become more serious in the future.

What is the link between smoking and COPD?
Suhas H S: Active smoking has been accepted as the most important risk factor for the development of chronic obstructive pulmonary disease. It is responsible for over 70 per cent of cases in high-income countries, although significantly fewer cases (approximately 40 per cent) are attributed to it in lower-income countries. The remaining risk is attributed to several environmental factors, including occupational exposure to dust and fumes, as well as indoor and outdoor air pollution. Passive exposure to cigarette smoke is accepted as an independent risk factor for heart disease and lung cancer and has also been implicated in the etiology of COPD. However, the association between passive smoking and COPD is less well-defined.

Does passive smoking lead to increased risk of COPD?
Suhas H S: Passive smoking, or secondhand smoke, refers to the inhalation of smoke by individuals who are not actively engaged in smoking. According to the World Health Organization, exposure to second-hand smoke leads to more than 880,000 deaths annually (Yin P et al, Lancet 2007). Exposure to second-hand smoke for 1 hour has been shown to reduce lung function for the following hour, and prolonged second-hand smoke exposure has been documented to increase respiratory symptoms such as breathlessness, wheezing, and susceptibility to asthma and chronic obstructive pulmonary disease.

Numerous epidemiological studies over the years have demonstrated the association between passive smoking and respiratory health outcomes, including COPD. A study published in a British medical journal in 2007 by Rachel et al found that nonsmokers exposed to secondhand smoke had a 2.25 times higher risk of developing COPD compared to unexposed individuals. Similarly, a meta-analysis conducted by Fischer F et al in 2015 reported a 1.66 percent increase in COPD prevalence among nonsmokers with high levels of secondhand smoke exposure.

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What is the mechanism of injury?
Suhas H S: Secondhand smoke (SHS) consists of 15 per cent mainstream smoke, inhaled and exhaled by smokers, and 85 per cent sidestream smoke emitted from the burning tip of a cigarette. Sidestream smoke is notably more toxic, and both contain a complex array of over 4,000 chemical compounds, including carcinogens and respiratory toxins, many of which are known to damage the respiratory system. Particulate matter, volatile organic compounds, and toxic gases can trigger inflammation and oxidative stress in the lungs, leading to airway narrowing and obstruction. The most common chemicals associated with smoke are:
1. Benzene: A chemical commonly found in gasoline.
2. Butane: A chemical commonly found in lighter fluid.
3. Ammonia: A chemical commonly found in household cleaning products.
4. Toluene: A chemical commonly found in paint thinner.
5. Cadmium: A chemical commonly found in batteries.
6. Formaldehyde: A chemical found in fertilizer, embalming fluid, and building materials.

Studies have shown that exposure to secondhand smoke can induce changes in lung function and increase the risk of developing COPD, particularly among nonsmokers.

What are the effects of secondhand smoking?
Suhas H S: It is well known that passive smoking can be harmful to one's health. Health issues linked to passive smoking include reduced lung function, eye and nasal irritation, an increased chance of dental problems, difficulties during pregnancy, and an increased risk of some cancers other than lung cancer.
Certain populations are particularly vulnerable to the harmful effects of passive smoking, including children, the elderly, and individuals with pre-existing respiratory conditions. In adults, it can lead to:
1. Cardiovascular diseases such as high blood pressure, arteriosclerosis, heart attack, or stroke. Research indicates that individuals have up to a 30 per cent higher likelihood of developing heart disease if regularly exposed to secondhand smoke.
2. Lung problems such as chronic obstructive pulmonary disease and asthma, resulting in faster decline in lung function and frequent exacerbations of lung diseases.
3. Increased risk of lung cancer and breast cancer.
4. Reproductive health problems such as low birth weight (when exposure occurs during pregnancy).

How does secondhand smoking affect people with COPD?
Suhas H S: For individuals with COPD to effectively manage their condition, adopting a supportive and health-conscious lifestyle is crucial. Since smoking exacerbates respiratory symptoms and accelerates the loss of lung function, quitting is essential to controlling COPD.

Secondhand smoking can worsen outcomes for individuals already living with COPD, exacerbating symptoms and hastening disease progression. A longitudinal study published in a British medical journal by Nirupama et al in 2015 found that COPD patients exposed to secondhand smoke experienced a more rapid decline in lung function and a higher rate of exacerbations compared to those in smoke-free environments. Furthermore, exposure to secondhand smoke has been associated with increased mortality among COPD patients, highlighting the importance of avoiding passive smoking for disease management. In children, it can lead to:
1. Frequent coughing, sneezing, shortness of breath, or other breathing problems.
2. Frequent and more severe asthma attacks.
3. Recurrent respiratory infections, such as bronchitis or pneumonia.
4. Sudden infant death syndrome (SIDS).
5. Increased risk of brain tumors and lung cancer.

What individual measures can be taken to reduce secondhand smoke exposure?
Suhas H S: Here are some practices which we can adapt in our daily lives to reduce exposure to secondhand smoke:
1. Stay away from areas where people smoke, which means avoiding venues and spaces where smoking is allowed.
2. Open windows and use air filters to lower some of the toxins found in burning tobacco.
3. Move away from smoke and find a smoke-free place to stand or sit.
4. Ensure guests in your home know they cannot smoke.
5. Do not let passengers smoke in your car, even with the windows down.
6. Although the number of people who smoke tobacco products has consistently decreased over the last several decades, one survey found that 1 in 4 nonsmokers still breathe in secondhand smoke.
7. It is acceptable to ask people not to smoke in your car or home.

In addition to these measures, screening programs and increased awareness are vital in order to identify high-risk patients and enable prompt intervention in order to prevent irreparable lung damage. In addition, comprehensive treatment programs can assist in addressing the complex nature of COPD, hence enhancing quality of life and symptom management.

The management of COPD involves a range of tactics, such as dietary adjustments, breathing exercises, vaccinations, anti-addiction techniques, lifestyle modifications, and routine monitoring. Non pharmacologic treatments are equally significant.

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