To examine the effects of secondhand or passive smoking, Japanese researchers exposed 30 healthy male medical students, to environmental smoke in a room for 30 minutes. The room used in this study was actually a smoker’s room very near to the hospital.

Each volunteer underwent through a series of medical tests including heart rate, blood pressure and ECG before and after entering the room. The results revealed that exposure to secondhand smoke do not cause any significant changes in the above mentioned parameters. However, the scientists also measured the impact of smoke on coronary artery blood flow by administering adenosine triphosphate (a drug that widens arteries) using Doppler echocardiography to monitor blood flow in one of the major coronary arteries.

Even before entering the room, the smokers among the volunteers showed a reduced flow of blood in coronary artery and the passive smoking does not cause any worse. On the other hand secondhand smoke has a dramatic effect on nonsmokers reducing their coronary artery blood flow rates to the same abnormally low levels as those of the smokers in a short span of 30 minutes.

This study demonstrates that passive smoking impairs endothelial function, preventing arteries from widening when they should. In older men with coronary artery disease, smoking can trigger angina or other related symptoms and this study results suggest that endothelial dysfunction can be an explanation. Furthermore, the research helps explain how passive smoking causes heart disease.

The Japanese research shows that even a brief exposure to secondhand smoke will impair the endothelial function. Another study from Florida USA, found that just one cigar impairs endothelial function, the other studies also tell us that secondhand smoke makes platelet more sticky and increasing the risk of artery blocking clots. This smoke also increases the carbon monoxide levels and lowers HDL (“good”) cholesterol.