The Truth About Cannabis Smoke: A Study

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, The Truth About Cannabis Smoke: A Study, ISMOKE

With recreational and medical marijuana being decriminalized in many areas in the US, more users than ever are toking up in the comfort of their own homes.  But even in places where there are no legal issues with using marijuana, users typically prefer to keep their activities private, and courteously try to confine the smell of their marijuana use to their homes or apartments.

At, we are concerned about the air quality of those around marijuana smokers, as well as the smokers themselves, so we commissioned a study to find the best methods for smokers to use to prevent particulate and odors from being released into the air. What follows are the results of our experiment (conducted in Colorado) measuring the scent of marijuana smoke in a typical apartment.

 Goals of the study

In our study, we aimed to determine which forms of smoking create the largest amount of marijuana odor around or outside an apartment.  For this experiment, we used a one bedroom, one bathroom apartment. Smoking was done in the bathroom, as is typical of those trying to hide the smell, with one room (the kitchen) between the bathroom and the front door.

Analyzing the data

According to research done prior to testing, we found that the typical sizes of marijuana smoke particles fell in the .3 to .5 micron range – as small as 1/300th of the width of a human hair.  To measure how common each type of particle was, our testing utilized the Fluke 985 Particle Counter, which counts the total number of particles of different sizes over a given period of time. In our experiment, the smoke was tested over a span of 70 seconds – the time necessary to test one liter of air.  Measurements were taken at the following times and locations:

  • The bathroom, 60 seconds after smoking

  • The kitchen, 3 minutes after smoking

  • Directly inside the front door, 5 minutes after smoking

  • Directly outside the front door, 7 minutes after smoking

Between each test, the entire apartment was thoroughly aired out to bring all levels back to their baseline.

 Average baseline particle measurements

                      Bathroom                    Kitchen                Inside door                       Outside door

.3 microns:  95,654.33                108,232.33                112,301.67                          157,482.33

.5 microns:    17,271.00                 21,686.00                  22,349.67                          21,908.33

1 micron:       3,179.33                    2,533.67                      4,996.00                            4,017.00

 Our tests focused on two principal areas:

1. How smoke spread throughout the apartment when using different smoking methods, including:

  • A puff from a joint

    , The Truth About Cannabis Smoke: A Study, ISMOKE
  • A single hit from a bong

  • A single hit from a bowl

  • A single hit from a vaporizer, the Magic-Flight Launch Box

2. How effectively five different designs of “sploofs” eliminated the smell and particles from the air when a single bowl hit was fully breathed out through the sploof.

The results

  1. As predicted, the particles in marijuana smoke fell into the .3 to 1 micron range. These were the only particle sizes whose levels had changed after smoking.

  2. Smoking from a bowl created the least smoke, followed closely by smoking from a bong, and then a puff from a joint. However,  all three of these methods were very similar in the amount of smoke they created:

    1. 5-10x the typical .3,.5 and 1 micron particle counts in the bathroom.

    2. 2-4x the typical .3, .5, and 1 micron particle counts in the kitchen.

    3. 2-4x the typical .3, .5, and 1 micron particle counts just inside the door.

    4. No elevated particulate counts were found outside the door of the apartment in any tests.

  1. The vaporizer showed only a 2-3x increase in the particle count for .3, .5 and 1 micron ranges in the bathroom only. No increase was found in the kitchen, inside the door, or outside the door.

  2. All of the  sploofs were somewhat effective in reducing particle concentrations.  They nearly eliminated any elevated particle counts in the kitchen, and no elevated particle counts were found inside the door or outside the door.

  3. Sploofs 1 and 3, incorporating activated carbon, worked best and were about 2x more effective at reducing particulate counts. This reduced the overall smoke levels to those created by a vaporizer.

Final conclusions:

  1. Smoking in a room with the door closed, at least one room away from the front door, should be enough to keep the smell from escaping the front door –  provided that you don’t smoke more than a few large hits.

  2. There isn’t a significant difference between the smoke and odor created by joints, bowls, and bongs.

  3. Vaporizing can be done safely anywhere within an apartment, without risk of the smell escaping.

  4. Sploofs work very well when used in a separate room away from the front door, and sploofs with activated carbon are more than twice as effective as sploofs without activated carbon.

, The Truth About Cannabis Smoke: A Study, ISMOKE, The Truth About Cannabis Smoke: A Study, ISMOKE