Cigarette smoke consists of two constituents: 15% of cigarette smoke is the main stream and 85% is the side stream distributed into the environment from the burning cigarette between puffs[3
While these two streams are similar in quality, their quantity differs as the amounts of carbonmonoxide, benzopyrene, ammonia and other carcinogenic substances are higher in the side stream than in the smoke inhaled by the smoker[4
Passive smoking has been associated with endothelial damage in healthy children and young adults, suggesting early arterial damage[13
]. The impact of cigarette smoke is exerted on peripheral vasculature via the above mentioned substances to disrupt the function of vascular endothelial cells and jeopardize perfusion to vital organs, resulting in disorders of peripheral vasculature and increased risk of cardiovascular diseases [4
Our findings indicate that systolic and diastolic blood pressures are higher in the exposure group compared to the non-exposure group; however, after consideration of the gender variable, the difference between exposed and non-exposed girls and boys was not significant.
Previous studies conducted on the effects of cigarette smoke on children’s blood pressure or studies on adults who were exposed to cigarette smoke in childhood have yielded different results. In the study of Simonetti et al. blood pressure was determined in 3786 preschool children and parents’ smoking habits were documented. Significantly higher blood pressure values were observed in children of smoking parents. (the mean Sys BP in exposed children was +1.2 mmHg higher than in not-exposed children, P
In another study by Feely and Mahmood, acute changes of blood pressure before and after exposure to cigarette smoke were measured in 21 young adults and compared to 12 healthy controls. The findings indicated that exposure to cigarette smoke after 60 minutes only resulted in systolic hypertension in brachial artery and aorta in the male group. The diastolic blood pressure in aorta and brachial artery of the male and female groups did not alter considerably before and after exposure to cigarette smoke[14
In a Turkish study by Agirbasli et al family history of coronary artery disease and current smoking history of family members were not significantly associated with systolic and diastolic hypertension in their children (hypertension was defined as having a systolic or diastolic blood pressure >95% percentile for age and gender)[10
Geerts et al reported the exposure of pregnant mothers to cigarette smoke, whether as secondary exposure to smoke or smoking by the mother herself, to be associated with higher systolic blood pressure in their newborns[11
A study by Hunk evaluated the impact of smoking parents on diabetes, hypertension and metabolic syndrome in their male adult children retrospectively. Data regarding the smoking status of parents during the prenatal period and childhood were obtained with questionnaires. The findings indicated that after correction for age, gender, race, education and smoking status of the person, participants whose parents were both smokers had a 1.55 fold increase in their risk for adulthood hypertension[15
Our study also indicates that systolic and diastolic blood pressures are higher in school children who are exposed to cigarette smoke. Since signs of atherosclerosis begin to develop during the first decade of life, particularly in high-risk individuals such as those with hypertension, diabetes mellitus, and familial hypercholesterolemia, the exposure group is more likely to develop cardiovascular diseases in the future.
After addition of the gender variables, both the girls and the boys groups did not indicate a significant difference between exposed and non-exposed individuals. However, in the girls group, the difference was close to the level of significance, and therefore larger sample sizes may yield significant differences.
The greater impact of cigarette smoke on girls may be due to their longer presence at home and consequently greater exposure to smoke or it may reflect their intrinsic sensitivity to cigarette smoke.
Unlike the other factors of cardiovascular diseases, exposure to cigarette smoke is easily omissible; therefore, the authors recommend that given the sensitivity of parents about their children’s health, the results of this study and similar studies be used for encouraging parents to quit smoking or smoke in places isolated from their children.
There are certain limitations in our study, the most important of which is the provision of inaccurate information by parents in questionnaires. Nevertheless, we tried to circumvent this challenge by not mentioning the children’s names on questionnaires and comparing the information with the data recorded in students’ health certificates (which contain information regarding the smoking status of the parents) to eliminate those questionnaires with discrepancy.
Another challenge was to control children’s anxiety and activity, particularly those in the first and second grade, during blood pressure measurement. This problem was relatively controlled through entertaining and calming the children prior to measurements.