Marijuana has same lung effect as smoking

WELLINGTON, New Zealand, July 31 (UPI) -- A single marijuana joint has the same effect on the lungs as smoking up to five cigarettes at once, according to a New Zealand study.

Researchers at the Medical Research Institute of New Zealand base their findings on 339 adults up to the age of 70, selected from an ongoing study of respiratory health, and categorized into four different groups -- those who smoked only marijuana, equivalent to at least one joint a day for five years; those who smoked tobacco only, equivalent to a pack of cigarettes a day for at least a year; those who smoked both, and those who did not smoke either marijuana or tobacco.

Marijuana smokers complained of wheeze, cough, chest tightness and phlegm, but emphysema was only seen in those who smoked tobacco, either alone or in combination, according to the study published in the the journal Thorax.

However, marijuana smokers still damaged the lungs and stopped them from working properly. Marijuana diminished the numbers of small fine airways, which are important for transporting oxygen and waste products to and from the blood vessels effectively.

The extent of the damage by the marijuana was directly related to the number of joints smoked, with higher consumption linked to greater incapacity, according to the study.