Carbon monoxide, a tasteless, colorless, and odorless gas has been known to be a silent killer as it can put whole families at risk without them ever knowing. So it would come as a shock to everyone that a study found that inhalation of the deadly gas has a good effect.

According to Itzhak Schnell of Tel Aviv University's Department of Geography and the Human Environment, low levels of the poisonous gas has a narcotic effect that helps people in the city cope with other harmful environmental factors in the urban setting.

The discovery was made by accident as it was made in a study designed to study the impacts of environmental stressors on the human body.

In the study, Schnell asked 36 healthy individuals, ages 20 to 40, to spend two days in Israel's busiest city - Tel Aviv. Traveling to various routes and sites, the impacts of environmental stressors on the participants were monitored. The stressors were the heat and cold, noise pollution, carbon monoxide levels, and the impact of the crowds.

After the activity and after the participants' report, noise pollution topped as the major city stressors. But more importantly, when Schnell was looking at the levels of CO that the participants inhaled, the professor discovered that the presence of the gas had a narcotic effect on the participants which helped counter the stress caused by the stressors in the city.

Though the gas is poisonous when inhaled in excess, Schnell noted that low levels of the gas had a beneficial influence, and that extended exposure to the chemical had no lasting effects.

However, CO must still be taken seriously as it has the potential to kill. Its deadliness comes from the fact that it inhibits the blood's ability to carry oxygen to the body, reported Regina Bailey of About.com.

Exposure to the gas has various negative effects that can range from mild headaches to nausea and serious headaches, to more serious symptoms such as unconsciousness, and worst of all, death.

The gas also has long term negative effects on those unknowing breathers. According to SilenShadow.org, a site which is dedicated to the dangers of the gas, long term effects of CO poisoning could affect a person's memory, brain function, behavior, and cognition.