It’s illegal to use it recreationally in the USA, but marijuana is the most commonly abused illicit drug in the nation. And a recent study found smoking marijuana may not be as harmful as smoking tobacco. The data revealed (duh) tobacco smoke does significant damage to the lungs. But breathe deep before reading about this other finding— marijuana smoke didn’t have the same effect.

Researchers asked more than 5,000 Americans (yeah, not the Dutch) to record their marijuana and tobacco use over 20 years and measured participants’ lung function at several points throughout the study. Tobacco smoke was linked to a decrease in airflow rate and lung capacity, but the word on weed was different: Even at moderately high marijuana use (one joint a day for seven years), researchers didn’t see decreased lung capacity. In fact, at low levels of marijuana exposure, smoking up was actually associated with improved lung function.

But the boost from marijuana smoke wasn’t large enough to benefit the lungs, and the data also suggests high levels of marijuana exposure are linked to a decline in airflow rate just like tobacco— so quit following Bob Marley’s lead. And while this study didn’t address other potential risks of lighting up, research suggests marijuana use can impair the immune system and may even increase the risk for heart diseaseMarijuana, immunity and infection. Klein, T.W., Friedman, H, Specter, S. Department of Medical Microbiology and Immunology, University of South Florida, Tampa. Journal of Neuroimmunology, 1998 Mar 15;83(1-2):102-15.An exploratory prospective study of marijuana use and mortality following acute myocardial infarction. Mukamal, K.J., Maclure, M, Muller, J.E., et al. Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Boston, MA. American Heart Journal, 2008 Mar;155(3):465-70..Still wanna’ get high? Go the natural route.