Secondhand smoke is bad for the heart

Dr Amitava Acharyya, CNS Correspondent, India
It has been known for long a time now that active cigarette smoking is an established risk factor for heart diseases. However, a large percentage of us are ignorant of the toxic effects of secondhand smoke—inhalation of cigarette, bidi, hookah smoke or inhalation of smoke produced by burning of coal or wood as fuel for cooking. This second hand smoking or passive smoking too is harmful and can lead to many diseases—like coronary obstructive pulmonary disease (COPD), asthma, stroke, hypertension, cancer, peripheral vascular disease, sudden infant death syndrome, low birth weight etc.

A good percentage of people, chiefly women, still use coal, wood or other forms of biomass fuels for everyday cooking purposes. They often blow air through a pipe to increase the intensity of the fire, getting exposed to a large amount of smoke. This is a familiar sight not only in rural areas but also in many urban slums. Moreover, the lone living room doubles up as a kitchen, and is, more often than not, poorly ventilated. All this results in the family members inhaling a lot of bio mass fuel smoke, making them vulnerable to a host of respiratory and heart diseases. 

Then again, even in households where gas and electric stoves are used, it is not unusual for the menfolk to smoke in the vicinity of the children and others, without thinking about the toxic effects of passive smoking on others.

Platelets are an essential blood component and exposure to secondhand smoke increases the likelihood of a thrombus (blood clot) which can lead to a heart attack. The activated platelets can damage the lining of the coronary arteries and facilitate the development and progression of atherosclerotic lesions. This increased platelet activation is associated with an increased risk for ischemic heart disease. Thus, increases in platelet activation observed in persons exposed to secondhand smoke is expected to have acute adverse effects.

In one study investigators checked the quality of platelets in response to passive smoking. The smokers and nonsmokers groups of people were made to sit in a room for 20 minutes where cigarettes had just been smoked. The researchers found no significant change among smokers, but a significant increase in platelet sensitivity to prostacyclin among nonsmokers, bringing them to a level similar to that of the smokers. These data, together with findings from other human studies, indicate that nonsmokers are sensitive to secondhand smoke, and even very low levels of secondhand smoke exposure can have a major impact on platelet function in nonsmokers.

Smoking is also associated with an altered lipid profile. It is scientifically proven that active smokers have higher concentrations of low-density lipoprotein (LDL) and decreased levels of high-density lipoprotein (HDL). This is the risk factor for heart diseases and stroke. A study found that adolescents and children whose parents smoked exhibited lower HDL levels than children who were not exposed to secondhand smoke.

Secondhand smoke exposure has been associated with lower levels of antioxidant vitamins in nonsmoking women whose husbands smoked. Despite a similar dietary intake of beta-carotene, retinol, L-ascorbic acid, and alpha-tocopherol, a dose-dependent relationship between the extent of exposure and plasma concentrations of betacarotene and L-ascorbic acid was observed in women exposed to secondhand smoke.

One experiment was conducted by exposing rabbits to secondhand smoke from standard (Marlboro) and nicotine-free cigarettes. In both cases, they produced similar levels of lipid deposits in the vessels. This observation suggests that nicotine is not the primary atherogenic (promoting the formation of fatty deposits in the arteries) agent but there are other products too in cigarette smoke that could be responsible for the atherosclerosis.

Secondhand smoke exposure induces atherosclerotic-like changes (thickening of the walls of arteries from fat deposits on their inner lining) in experimental animals after only a few weeks of exposure to secondhand smoke at levels similar to those experienced by people in normal day-to-day life. These findings provide strong support for the epidemiological evidence that exposure to secondhand smoke can cause heart disease.

Keeping all this in mind, the theme of World No Tobacco Day 2018 was ‘Tobacco and Heart Disease’. In a webinar hosted by CNS, Prof Rishi Sethi, Department of Cardiology, King George's Medical University (KGMU) highlighted the burden of tobacco from a public health point of view. His valuable messages should be incorporated in tobacco control 

campaigns to create massive awareness among policy makers, smokers and the non smokers. We must celebrate each day as “No Tobacco Day” and make our society free from harmful smoke. Everybody should have the right and wherewithal to inhale smoke free fresh air in all environments.
Dr Amitava Acharyya, Citizen News Service - CNS
June 19, 2018