Impact of E-cigarettes on Respiratory Symptoms: A Literature Review

Introduction
Electronic cigarettes, commonly called as e-cigarettes, are the electronic gadget that generate a
smoke‐like spray known as vapour. The consumer inhales the vapour. This vapour produced by
the e-cigarettes characteristically has nicotine content but majority of the other chemicals that
people are exposed to with conventional cigarette smoking. E-cigarettes are popularized among
the people who smoke nut want to cut down on the hazards of smoking. It is reported through
several studies that e-cigarettes use may enhance the vulnerability to respiratory infections. But
the data on the issue of respiratory health of e-cigarettes users is limited. The given study is done
to investigate the alterations in respiratory manifestations in individuals who smoke traditional
cigarette and swapped to vaping for minimum of two month period. An on-line survey was
conducted to examine the subjective changes. The research found that 29% participants claimed
no alterations in respiratory manifestations, 5% claimed deterioration, and 66% claimed
improved condition. So, the study concluded that the shift from smoking to vaping is related to a
decreased occurrence of self-reported respiratory symptoms and identified the need of more
research which can use objective measures in randomly selected samples. However, this study
has several limitations. The reporting was subjective and it could be possible that the e-
cigarette’s users attempted portraying vaping in a positive light to reduce the anti-vaping ideation
of public health and media reporting of vaping. Another limitation is that vapers who faced
negative impacts while vaping may have left using e-cigarettes and were not part of the sample.
Findings of this study were in contrast with the findings of cell culture and animal studies, but
those studies also had various limitations. Moreover, human studies have not found any negative
impacts of vaping.
One of the major preventable causes of death and disability, and social disparity in health in the
UK is smoking (Tobacco Advisory Group of the Royal College of Physicians , 2016). If nicotine
is provided to the addicted smokers devoid of the damaging elements of tobacco smoke, majority
of the damage from smoking can be prevented. E-cigarettes provide nicotine without the burning
of chemicals and for this reason, regarded as a safer option than traditional cigarettes. However,
some cell and animal researches have indicated the possibility of risks proposing that vaping may
enhance the vulnerability to respiratory infections. Cigarette-smokers who have attempted to quit

using other methods and failed can be motivated to try e-cigarettes to quit smoking and the stop
smoking services need to assist e-cigarette smokers in quitting by providing behavioral support
to them. There is a lack of evidence regarding the usefulness of e-cigarettes in undermining the
long-term reduction in cigarette smoking among young adults, and may actually be playing a
part in promoting it. An overall shift has been observed towards the incorrect perception of e-
cigarettes having as adverse effects as the conventional cigarettes in the past year as opposed to
the current estimation that using e-cigarette is approximately 95% safer than traditional cigarette
smoking (Preston, 2015). Further investigation is required in this area. This literature review is
conducted to find evidence in favour and against the use of e-cigarettes in causing respiratory
symptoms.
Method
Literature was reviewed systematically. Relevant articles were found through the databases of
MEDLINE, ScienceDirect, PubMed, CINAHIL and many more. The studies published in last 10
years and in English language were selected. Studies which examined the link between e-
cigarette use and respiratory infections were considered. Several long and short terms were
included to search for the topic. Keywords used for primary search were “e-cigarettes” and
“vaping” “respiratory symptoms”, “respiratory infections”, “vapers”, “nicotine”. Boolean
operators (AND, OR) were used to make the search more focused and productive. Another
search was undertaken using medical subheading (MeSH). In addition, Google Scholar was used
for search. Lastly, all the retrieved articles were checked for their reference list manually and any
relevant article were included. Abstracts of the selected articles were screened to determine if
they were specifically relevant for the research topic. After that, the articles were analyzed for
presentation of data regarding the association between vaping and any measure of respiratory
symptoms. 46 studies were found, out of which 12, articles are eventually included in the
literature review. Two major themes were identified, Adverse effects on the airways and E-
cigarette used an aid to quit or cut down smoking. One denoted the positive aspect effect of
vaping while other indicated towards the negative aspect.
Inclusion criteria
1. Pertaining to the research topic

2. Published within 2009-2019
3. English language
Exclusion criteria
1. Older studies
2. Non-English
Discussion
Adverse effects on the airways
It can be said that e-cigarettes have gained huge increases in popularity in last five years because
of excessive marketing, enhanced constraints on the usage of on traditional cigarettes, and a due
to the perception that e-cigarettes are safer substitutes to conventional cigarettes. Current studies
have established that e-cigarettes can aid smokers in quitting smoking and lower their cigarette
use. Evidence is also found that e-cigarettes can inspire quitting or cigarette use decline even
among the people who don’t intend to quit or reject the support. The consumption of e-cigarettes
is increasing rapidly particularly among youth as e-cigarettes are perceived as a safer option as
compared to the traditional cigarettes. But, the evidence considering the impact of e-cigarettes on
the lung is very scarce. A study was conducted is to ascertain if use of e-cigarette changes the
subject airway epithelial functions against respiratory viral infection. The study revealed that
nicotine-free e-liquid promoted IL-6 generation and HRV infection. Including nicotine into e-
liquid enhanced the impact of nicotine-free e-liquid. Result of this study provided a strong
evidence for the adverse effects on the airways of young individuals by the e-cigarettes
particularly the airway epithelial inflammation and innate immunity. Moreover, this study can
guide future research to assess the effect of e-cigarettes on lungs of human, particularly the youth
so that public can be informed regarding the potential health risks of e-cigarettes (Wu, et al.,
2014). However, this study has several limitations. Several e-cigarette components such as
propylene glycol have received approval from the FDA to be consumed by humans as liquid,
however their safety in the form of vapor for inhalation is not researched. A recent study
revealed well-distinguished young hTBE cells at the air-liquid interface culture to tobacco-
flavored e-cigarette vapour with the use of a cell exposure chamber as indicated in past tobacco
cigarette smoke study (Wu, et al., 2012) (Zhang, et al., 2011). Second limitation is that this study