Passive smoking - a comparison between a traditional cigarette and the e-cigarette

Smoking traditional cigarettes carries a risk for the user, but also to the people in their surroundings. To fully undestand the implication of this issue, several terms were introduced. The smoke was divided into the main jet, which is inhaled directly into the lung, and auxiliary jet which is emitted at the front of the lit cigarette. Passive smoking consists in breathing in the mix of the smoke exhaled by the cigarette user and the auxiliary jet. In professional scientific language, this mix is called ambient smoke. 

For e-cigarettes, the phenomenon of auxiliary jet does not occur. The evaporation mechanism of the nicotine liquid is initiated only when inhaling.
Passive smoking may only be considered in the context of vapors exhaled by the e-smoker into the environment.

Types of cigarette smoke and aerosol in traditional cigarettes (A) and electronic cigarettes (B) 
Illustration 1.

Analyzing passive smoking, the researchers found out that the concentration of toxic and harmful substances in the auxiliary jet of a traditional cigarette is much higher than in the main jet. This means that inhaling the smoke from a lit cigarette is much more harmful than direct inhalation (Chart 1). Since passive smokers are mostly subject to the auxiliary smoke, their health is at much higher risk than was previously thought.


The comparison of concentration of substances in the main and auxiliary jet 1
Chart 1.

Numerous studies have identified more than 5600 different chemical compounds in cigarette smoke. However, despite rapid advancements in science and technology, several compounds remain unidentified. Cigarette smoke consists of two phases,gaseous and molecular, in which about 400-500 chemical compounds may be identified in gaseous form, and about 3500 chemical compounds in molecular phase.2 Gaseous phase composition is mostly nitrogen oxides, acetic aldehyde, pyridine and N-nitrosamines.  Many of these substances are harmful, e.g. N-nitrosamines are potentially cancerogenic.3

In the molecular stage, we see, among others, polycyclic aromatic hydrocarbons (PAH), alcohols, phenols, heavy metals and pyridine alkaloids (e.g. nicotine).4,5,6 Many of these substances are harmful, for example polycyclic aromatic hydrocarbons (PAH) and some of the heavy metals are cancerogenic substances.

For e-cigarettes, the situation is very different. There are far less substances created when creating the aerosol. Due to the limited pool of chemical compounds, it is much easier to test what exactly is being inhaled by the e-smoker. The e-cigarette “smoke” was tested and proven not to contain harmful substances such as toluene, benzene, styrene, naphthalene, hexanal or valeric aldehyde which are present in the traditional cigarette smoke.  The only major chemical compound found in the e-smoker’s environment is nicotine. However, recent studies show that the exposure of passive smokers to the effects of nicotine from e-cigarettes is as much as 10 times less than for traditional cigarettes - detailed data will be published at the international conference in Boston: Czogała et al. SRNT 2013.


1. J. Turiel, Indoor pollution and health hazards, Wiley&Sous, NY (1998).

2. W. Piekoszewski, E. Florek: Markery narażenia na dym tytoniow, Katedra i Zakład Toksykologii, Akademia Medyczna, Poznań, (2001).

3. D. Hoffmann, I. Hoffmann, K. El-Bayoumy: The Less Harmful Cigarette: A Controversial Issue. A Tribute to Ernst L. Wynder, Chem. Res. Toxicol., 14 (2001) 767-790.

4. D. Hoffmann, I. Hoffmann: The changing cigarette 1950-1995, J. Toxicol. Environ. Health., 50 (1997) 307-364.

5. D. Hoffmann, E.L. Wynder: Aktives und passives Rauchen, Lehrbuch der Toxikologie. H. Marquardt, S.G. Schafer. Mannheim, Leipzig, Wien, Zurich, BJ-Wiss.-Verl. (1994) 589-605.

6. M. Kulza: Interakcje metaboliczne pomiędzy dymem tytoniowym a alkoholem etylowymRozprawa Doktorska, Poznań (2011).