Air Concentrations of Nitrogen Oxide Related to Tobacco Smoke: A Systematic Review

Environmental tobacco smoke (ETS), similar to firsthand and secondhand smoke, is a complex mixture containing thousands of chemicals, many of which are known as carcinogens. The high combustion temperature of tobacco and the presence of nitrogen in the tobacco can lead to the release of nitrogen oxides (NOx). From the NOx, NO2 irritates the respiratory system and damages cells and mucous membranes of the lungs. The selected databases for this systematic review were Science Direct, Springer, PubMed, and Google Scholar, and the keywords of the search plan included “nitrogen oxide”, “NOX”, “ETS”, “Cigarette smoke”, “Waterpipe smoke”, and “Tobacco smoke”. Finally, 797 articles were found, and after reviewing, 7 articles met our criteria. The results demonstrated that the mean air concentration of tobacco smoke related-NOX was 9.71 ± 11.03 ppm, which was higher than the annual guideline level of free air quality (0.053 ppm). The mean concentration of NOX in cigarette smoke was 329.45 ± 465.43 ppm, and for smoking places, it was higher than for nonsmoking places (17.80 vs. 12.47 ppm). Moreover, for the cigarette smoke, it was higher than for the waterpipe smoke (5.66 vs. 0.16 ppm). In this regard, the cigarette is more suspected to the emission of NOx compared to waterpipe, and tobacco smoking can expose people to high levels of NOx regarding the limited guideline levels. Finally, the concentration of NO in cigarette smoke and air was higher than NO2.