
I got a similar reaction during a discussion in a psych class. Google Scholar is giving me trouble finding free papers but here is some information from a NEJM article:
We conclude that smoking marijuana, regardless of tetrahydrocannabinol content, results in a substantially greater respiratory burden of carbon monoxide and tar than smoking a similar quantity of tobacco. (N Engl J Med 1988;318:347–51.)
Pulmonary Hazards of Smoking Marijuana as Compared with Tobacco
Tzu-Chin WU, M.D., Donald P. Tashkin, M.D., Behnam Djahed, M.D., and Jed E. Rose, Ph.D.
N Engl J Med 1988; 318:347-351February 11, 1988DOI: 10.1056/NEJM198802113180603
http://www.nejm.org/doi/pdf/10.1056/NEJM198802113180603
I apologize for the use of the term "looser". It is not very precise and carries a certain air of an emotional reasoning fallacy. Now, on the cognitive effects of weed use:
In conclusion, high-potency marijuana was shown to consistently impair executive function as assessed in the Tower of London task. Motor control was likewise impaired as indicated by a decrement in tracking performance in the Critical tracking task and a decrease in motor impulse control during Stop signal task performance...
Neuropsychopharmacology (2006) 31, 2296–2303. doi:10.1038/sj.npp.1301068; published online 29 March 2006
Clinical Research
High-Potency Marijuana Impairs Executive Function and Inhibitory Motor Control
Johannes G Ramaekers1, Gerhold Kauert2, Peter van Ruitenbeek1, Eef L Theunissen1, Erhard Schneider3 and Manfred R Moeller4
http://www.nature.com/npp/journal/v31/n10/full/1301068a.html
Please, lend me your support for smoking weed.