1 Introduction
The World Health Organization estimates that tobacco causes approximately
5 million deaths annually worldwide, and this number is expected to double by
2025. The reason for that high number is that Tobacco use is a major cause
of many of the worlds top killer diseases including cardiovascular disease,
chronic lung disease and lung cancer. Smoking is often the hidden cause of
many killing diseases. In Saudi Arabia, the prevalence of current smoking
ranges from 2.4-52.3% (median = 17.5%) depending on the age group. The
results of a Saudi modern study predicted an increase of smokers number in
the country to 10 million smokers by 2020. The current number of smokers
in Saudi Arabia is approximately 6 million, and they spend around 21 billion
Saudi Riyal on smoking annually. Clearly smoking is a prevalent problem
among Saudis that requires intervention for eradication. Persistent education
of the health hazards related to smoking is recommended particularly at early
ages in order to prevent initiation of smoking [3, 17]. Tobacco use is considered
a disease that can spread through social contact in a way very similar to the
spread of infectious diseases.
Like many infectious diseases, mathematical models can be used to un-
derstand the spread of smoking and to predict the impact of smokers on the
community in order to help reducing the number of smokers. Castillo-Garsow
et al. [7] presented a general epidemiological model to describe the dynam-
ics of Tobacco use and they considered the e¤ect of peer presure, relapse,
counselling and treetment. In their model the population was devided into
non-smokers, smokers and smokers who quit smoking. Later, this mathemat-
ical model was re
ned by Sharomi and Gumel [14], they introduced a new
class Qt of smokers who temporarily quit smoking. They concluded that the
smoking-free equilibrium is globally-asymptotically stable whenever a certain
threshold, known as the smokers-generation number, is less than unity, and
unstable if this threshold is greater than unity. The public health implication
of this result is that the number of smokers in the community will be e¤ectively
controlled (or eliminated) at equilibrium point if the threshold is made to be
less than unity. Such a control is not feasible if the threshold exceeds unity.
Later, Lahrouz et al. [11] proved the global stability of the unique smoking-
present equilibrium state of the mathematical model developed by Sharomi
and Gumel. Zaman [18] derived and analyzed a smoking model taking into
account the occasional smokers compartment, and later [19] he extended the
model to consider the possibility of quitters becoming smokers again. Erturk
et al [8] introduced fractional derivatives into the model and studied it numer-
ically. Zeb et al.[20] presented a new giving up smoking model based on the
model in [18] for which the interaction term is the square root of potential and
occasional smokers. Van Voorn and Kooi [16] presented a three compartment smoking model which was studied using brute force simulations for the short
term dynamics and bifurcation analysis for the long-term dynamics. In 2013
[1], we adopted the model developed and studied in [11, 14] and considered
the e¤ect of peer pressure on temporarily quitters. By this we mean the e¤ect
of smokers on temporarily quitters which is considered one of the main causes
of their relapse.