Based on the fifth Korea National Health and Nutrition Examination Survey conducted between 2010 and 2012, the team analyzed 6,043 men and women who had no history of smoking and determined that those who were exposed to second-hand smoking had a record of having self-destructive thoughts for a period of more than two consecutive weeks.

The analysis showed that, setting aside age, profession, earnings level, academic backgrounds and other variables that are known to have correlations with depression and suicidal thoughts, there was a clear damage to the people’s psychological well-being caused by second-hand smoking.

Among the people studied, 3,006 who had exposure to indirect smoking had 1.43 times higher risk of harboring suicidal thoughts than the 3,037 who didn’t.

The correlation between indirect smoking and suicidal thoughts showed minor differences according to the place of exposure and the affected person’s gender.

Men had increased risk of 2.49 times more chance of having depression.

Women who faced second-hand smoking at home had 1.55 times more cases of considering suicide and 1.46 times more risk of going through depression.

The medical team said the toxic substance in cigarette smoke cuts down on the neurotransmitter compound such as dopamine, and that this combined with the stress accumulated from inhaling unwanted unhealthy substance pushed people to depression.

Professor Yoo of the research team stressed the need for governmental regulation to decrease second-hand smoking as it clearly poses a threat to people’s psychological health as well as the pre-known physical damage.

The research was published in the April issue of journal Family and Environment Research.

Effective Sunday, smoking within 10 meters’ distance from public subway exits has been banned in Seoul, punishable by less than 100,000 won ($90) fine.

By Lim Jeong-yeo (kaylalim@heraldcorp.com)