Effects of Involuntary Smoking and Vaping on the Cardiovascular System

In deaths and diseases attributed to tobacco smoke cardiovascular events exceed cancer and respiratory diseases. Second hand smoke (SHS) promotes the development of arteriosclerosis and can also trigger acute changes of endothelial function and of blood coagulability. Indoor smoking bans reduced coronary syndrome and myocardial infarction 10-20% within one year and were followed by sustainable decreases of stroke and diabetes. With a smoke-free hospitality industry people recognized tobacco smoke as an air pollutant, smoking in public was denormalized and social acceptance of smoking in front of children and pregnant women decreased also in homes and in cars. Combined effects with ambient air pollution are proven for active smoking and suspected for SHS. Contamination with third hand smoke (THS, “cold smoke”)  persists for months in homes and cars, creating secondary pollutants that in some cases are more toxic (e.g., tobacco-specific nitrosamines).  Remnants found in air, dust, and on surfaces (carpets, wallpapers, upholstery, soft toys) were associated with their metabolites in saliva and urine of children and with elevated levels of nicotine on hands and cotinine in urine of nonsmokers residing in homes previously occupied by smokers. In animal experiments effects of THS were found on thrombogenesis, insulin resistance through oxidative stress, on the developing immune system, lipid metabolism and alterations in liver, lung, skin and behavior. Much less is known about health effects for bystanders from the aerosols exhaled during “vaping” of e-cigarettes, but nicotine and other toxins from e-cigarettes are certainly a hazard, which should be prevented by the use of dermal and oral nicotine products, which are safer for nicotine replacement and without risk for bystanders.


Introduction
Cardiovascular deaths from tobacco use and secondhand smoke (SHS) exceed deaths from cancer and respiratory diseases attributed to tobacco smoke [1][2][3]. But many smokers are still unaware of the link between tobacco smoke and cardiovascular diseases (CVD), e.g. stroke [4], even in countries like China where many strokes from smoking in men and from SHS in women occur [1,5,6]. Information on links between tobacco use or exposure on heart attacks, stroke, peripheral vascular disease and impotence is still news for many people and even medical doctors sometimes doubt that SHS causes CVD, because they occur less frequently than in active smokers. Therefore the following expert judgement focuses on CVD from involuntary exposure.

Burden of CVD from SHS
Worldwide, 40% of children, 33% of male non-smokers, and 35% of female non-smokers were

SHS Effects in Children and Unborn
The younger the child the more vulnerable it seems to be, especially for SHS effects on brain and Heated tobacco products (HTPs) are marketed as less dangerous than conventional cigarettes because of less products of pyrolysis, however, biomarkers of potential cardiovascular harm did not support this claim [77]. HTPs impair vascular endothelial function measured by arterial flow-mediated dilatation in rats to the same extent as by cigarette smoke [78]. An advantage of electronic devices over conventional cigarettes is that SHS is only produced when the user exhales the aerosols and not continuously like in conventional smoking released from the burning end of cigarettes between puffs. The doses calculated for SHS uptake from electronic devices were significantly lower, below 1.6×10 8 particles/kg bodyweight, than those due to combustion devices, but dosimetry estimates were 50% to 110% higher for HTPs than for e-cigarettes [79]. The carrier function of aerosols from e-cigarettes might be similar, but the clearance of liquid particles is certainly faster than of solid particles released by conventional cigarettes. On the other hand, harmful volatile organic compounds, tobacco-specific nitrosamines and heavy metals in electronic cigarettes can be even higher in e-cigarettes than in traditional cigarettes [80].
Electronic cigarettes have been called "wolf in sheep's clothing", because they may serve as a gateway drug for youth, prolong nicotine addiction and the ritual in smokers who would otherwise be willing to quit and keep up the handling and use of cigarettes in public [81]. Exposure of bystanders to products of pyrolysis are lower than in passive smoking, but exposure to nicotine is similar and particles in the aerosol are smaller [82][83][84][85]. Aerosols exhaled during vaping are less persistent than SHS, nevertheless they are carriers for toxins, which they adsorb on their large surface and transport them into the depth of the lung, where clearance is less efficient [81]. Contamination of neighboring rooms was found [86] and it has to be assumed that also passive vaping increases cardiovascular risks, which were found for active vaping [87,88]. Though exposure to nano-particles is not as high as in passive exposure to heated tobacco, the combination of ultrafine particles with nicotine and other toxins has to be regarded as a respiratory [89] and cardiovascular risk, which is avoidable [90]. For smoking cessation dermal and oral nicotine products from pharmacies are safer for nicotine replacement and do not contaminate the breathing air of bystanders [81]. Most worrying are associations found recently between e-cigarette use and myocardial infarction [91].

Funding
This research received no external funding

Conflicts of Interest
The author declares no conflict of interest.