Can you smell weed in a car after smoking?

At one point or another anyone interested in cannabis or who partakes in consuming it has probably wondered how easy it is to detect the scent of this pungent green flower. Described commonly as skunk-like, the distinct scent of cannabis probably feels impossible to hide. In light of controversy regarding the “in plain smell” law, many people are seeking to assess the chances of cannabis being detected – in other words, people want to know if weed smell stays in their car. It’s not uncommon for police officers to search citizens’ property, usually their vehicles, on the grounds of suspected cannabis possession based on smell. But in order for a search to be valid, it’s important to consider how easy it really is to detect the scent of cannabis in order to ensure these assumptions are lawful. So, let’s dive a little deeper into this topic!

What is the “in plain smell” law?

The “in plain smell” law is a law enforcement doctrine based on common sense. Essentially, if police can smell cannabis, they can search your property. These searches are common in vehicle stops and have raised a lot of questions about whether police can really smell marijuana in your car or if they’re searching your property unlawfully – and potentially profiling you. This law applies federally, so cannabis laws in California or cannabis laws in Maryland are identical in this particular case.

Can the police really smell weed from your car?

A study published in the March 2020 issue of Science and Justice tested how detectable the scent of dried cannabis flower was in a few different types of packaging. Considering the warrantless searches that the “in plain smell” law enables, this study is important in protecting people’s rights and ensuring police officers are only searching vehicles or property lawfully.

The study found that marijuana packaged in basic Ziploc sandwich bags was easily detected while marijuana that was packaged in double vacuum-sealed bags was less odorous and only detected occasionally.

Along with sandwich bags and vacuum sealed bags, the researchers had the study’s participants try to detect the scent in an open glass bowl, plastic produce bags, and pop-top canisters like those that marijuana is often sold in. Each participant was asked to detect the scent of 2 ounces of cannabis inside of the listed vessels. The study was conducted in a controlled test environment which begs the question, could the police really smell cannabis from your car?

Obviously, a car with its windows down on the side of the highway isn’t comparable to a specific testing environment in terms of scent permeability and air flow. And when you consider what type of packaging the cannabis is in, it is very likely that police can’t smell cannabis from your car unless it’s quite loosely packaged.

Where does cannabis get its scent?

Cannabis’ strong scent is indebted to its terpenes. In short, terpenes are organic compounds found in the oils of all flowers. Different strains of cannabis contain different terpenes, all which add to the flower’s scent and flavor. The prevalence and type of terpenes in any given strain can make the scent of the cannabis stronger. So, while all cannabis is bound to carry the signature skunk-like smell, some strains have a more potent scent than others.

What about the smell of weed smoke?

Compared to dried flower, the scent of cannabis smoke is easier to avoid. While it may be similar to cigarette smoke in terms of certain components, tobacco’ scent seems to linger on and around whoever has been smoking. Meanwhile cannabis’ scent doesn’t have as much staying power.

The chemistry of cannabis smoke, which contains plenty of ammonia and lacks acrolein, formaldehyde, and nitrosamines, makes for a cloud of smoke (and its scent!) that quickly dissipates into the air. Ammonia’s polarity combined with the polarity of water in air or showers carry away the smoke and its scent.

That being said, if someone was smoking marijuana in a confined space without much airflow, you’re likely to trap some of that skunk-like scent. But the vapors from a hot shower or an open window can help you clear it up in no time.

Consuming cannabis without leaving a scent

There are some rare scenarios in which cannabis consumption is essentially odourless. And that would be if you are consuming it in edible, beverage, capsule, or oil form. Vape pens and oil pens also reduce the strength of cannabis’ scent. But the smell isn’t completely erasable in any scenario!

Final Thoughts

It may not be possible to answer the question “how easy is it to detect the scent of cannabis?” full stop. It is definitely a nuanced answer dependent on circumstances, the strain of cannabis, and consumption method, or lack thereof if you are referring to dried flower that isn’t being consumed. That being said, studies such as the one mentioned above are very important in terms of protecting citizens from unwarranted searches by law enforcement and being able to defend their rights. I think this is an interesting thing for any cannabis connoisseur to consider, and more importantly, for researchers to continue working on to promote appropriate and reasonable law enforcement doctrines.

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