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Effects of Secondhand Smoke


Due to a shortage of conclusive scientific research on the subject, the effects of secondhand marijuana smoke are not fully known. However, we do know that it has at least some adverse health effects. Moreover, breathing in secondhand marijuana smoke causes similar physical and psychoactive symptoms as directly smoking marijuana, only to a milder degree. Depending on conditions and individual variation, bystanders can accumulate detectible levels of cannabinoids in their bloodstream and feel some cognitive effects. At sufficiently high concentrations, secondhand smoke can cause a "contact high" and lead to failed drug tests.

Marijuana vs. Alcohol

In arguments for marijuana legalization, it is often claimed that marijuana is "better than alcohol." We believe that the comparison is more nuanced than that. If the person next to you is drinking alcohol, none of it is entering your system. If you're standing next to a pot smoker, on the other hand, you're smoking right along with them. The amount you inhale may not be enough to make you legally "high." However, just as it's wrong to spike someone's drink with just a little bit of alcohol, it should not be acceptable to put any amount of THC in the air we all breathe.

Non-Users' Rights

Our position is that, if we are allowed to choose to consume psychoactive substances, then we should also have the right NOT to consume them. Secondhand smoke, especially when it is present in our homes because of smoking neighbors or nearby commercial operations, takes away that choice. Since marijuana users have ample alternative methods of ingestion available to them - tinctures and edibles, for example - we believe that smoking and vaping marijuana should be prohibited.

Our Solution

  • Prohibit airborne methods of THC consumption.

  • Prohibit any release of THC into the air (for example, by commercial processing).

  • Impose strict fire safety standards on all commercial marijuana operations and on home grows.

"...They breathed in so much marijuana smoke that they would have failed a drug test."

I live in a state where marijuana is now legal. My neighbor is taking full advantage of this new freedom. In the evening, when I enter my toddler’s bedroom, I can smell marijuana. My neighbor’s back porch is separated from my house by only a few feet. When he smokes in his backyard, the smoke drifts towards my house.

Do I have to keep all my windows closed? Or is there a way to stop my neighbor from smoking right next to my child’s bedroom?

One of my neighbors, although I don't know which one, smokes marijuana on a regular basis. Almost every night, I can smell it. I've identified that the smell appears to be coming down through my kitchen vent, as the smell always originates from the kitchen area, and is strongest near the vent. There does not appear to be any smell in the hallway, so my guess is that a downstairs neighbor is smoking and attempting to ventilate their apartment via their kitchen vent.

I've contacted my landlord already, who has informed me that there is not much he can do aside from sending out a notice to everyone "reminding everyone that smoking of any kind is a violation of the lease agreement," and that he cannot identify who is smoking, or where the smoke is coming from. He told me that he especially cannot do anything because medical marijuana is legal.

Source: Nolo

The scenario from a reader: The neighbors are new as of the beginning of September. They are recent college grads who seem fairly well off and pretty insular. (Meaning they're not the let's-meet-the-new-neighbor types.) They have some unknown office jobs. They both arrive home around the same time each night (7ish). And then just about every waking moment in the evenings, mornings and weekends, they're smoking pot. And it's likely not for medical reasons.

While the reader isn't opposed to you know, partying, he doesn't want to have to smell the weed all the time. It has become annoying.

My landlord didn't tell me before I moved in here a month ago that not only that existing tenants can smoke in the building (new tenants cannot), but our neighbor smokes cigarettes AND medical marijuana.

She smokes it at least once a day, and the smoke comes into every room of our large apartment, including over my baby's crib. My child is 5mo and I also have a 3 year old.

I have complained multiple times to the apt office staff, and apparently they are in the process of enforcing their MI landlord right to forbid her to smoke in the building (or to grow it!). I have only noticed an increase in the frequency of her smoking.

A nurse at my pediatrician's office said there is a MI or city ordinance that specifically protects me since I have an infant, but I can't find it anywhere!

This is causing me severe distress. Secondhand smoke increases the SIDS risk. I also didn't plan on my whole place smelling like weed.

Please help me.

Source: EV Grieve

I have nothing against pot but I'm sensitive to the stuff, I have really bad allergies so any sort of smoke makes me cough. So when I come [home] and have to open the windows to air out my unit just so I don't have a coughing fit it's a bit ridiculous. Not to mention I've had to wash some clothes in my closet that I wear for work so my work doesn't suspect anything. This is the third time it's been this bad in less than two months.

My landlord says they'll send notices to downstairs neighbors warning them and if it continues they'll take further action.

I know there isn't much a landlord can do since the duct system in the building links everyone, but I feel I should be able to not smell my neighbors when I come home. I don't want to be 'that neighbor' but this has to end.

I had neighbors move in this past weekend and everyday sometimes twice a day, they are smoking pot. I called Columbus Police after going to management here and the first time they came out, they smelled it in my basement where it was coming through but went next door and talk to them and left. I know it is only pot but the smell is so strong and so bad that I was up 3 hours last night venting my place. When it happens again (because it will), I will try to call again and see if I can get the cop to look into the basement window to see if they are doing it. Outside of that, I have informed management here and they gave them notice of a lease violation but who knows how long this will take to play out. I am trying to be a Police Officer and both my and my fiancee have employment where we are drug tested.


Health Effects on Bystanders
Contact Highs
Increased Risk of Stroke and Heart Attack

According to a study in the Journal of the American Heart Association (JAHA), even one minute of exposure to secondhand marijuana smoke causes blood vessels to dilate, increasing the risk of stroke, heart attack and atherosclerosis. 

This effect occurs even when the smoke concentration is so low that it is not visible.

Court Finds that Secondhand Smoke Makes Homes Uninhabitable

New York landlords may be required to ensure that apartments are free of secondhand smoke after a New York court ruling.

"New York courts have recently found that secondhand smoke constitutes a breach of the warranty of habitability, which is a non-waivable obligation imposed on all residential landlords [including co-ops] to insure that the premises are fit for human habitation and do not contain any conditions that would be dangerous, hazardous, or detrimental to tenants' life, health or safety," says Ian Brandt, a real estate lawyer at Braverman & Associates in Manhattan.

The First (Accidental) Study

Back in 1977, scientists were studying the effects of marijuana smoking when one of their control subjects reported feeling dizzy and nauseous.   He had a rapid heartbeat and his eyes were red.  These were the same symptoms shown by the marijuana smokers, and in fact his urine tested positive for marijuana exposure. 

It turned out that the control group had been placed in the same room with the smoking group, and this man had gotten the first scientifically reported "contact high."

It's worth noting that marijuana was much less potent then than it is today.

Like Smoking a Joint

In a 1986 study, five men were exposed to secondhand marijuana smoke for one hour a day, six days in a row.  It was found that inhaling secondhand smoke from 16 cigarettes produced the same subjective effects as smoking one joint.  Inhaling secondhand smoke from only four cigarettes also had an effect, though it was "less pronounced."

A trio of 2015 studies looked at the effects of secondhand marijuana smoke on nonsmokers, under both ventilated and unventilated conditions.

Even in ventilated conditions, the majority of the nonsmokers had detectible levels of cannabinoids in their blood, and they reported getting "the munchies."

Under unventilated conditions, the nonsmokers demonstrated an increase heart rate, impaired performance, and "mild to moderate self-reported sedative drug effects."  Several of their urine samples tested positive.

The authors concluded that exposure to high concentrations of secondhand marijuana smoke "mimicked, though to a lesser extent, active cannabis smoking."

Positive Drug Tests after Exposure

Source: ScienceDirect

Firefighters Get Stoned by a Warehouse Fire

In 2007, Texas firefighters were hampered by the effects of the fire they were fighting:  a burning warehouse of marijuana.

Firefighters spent half an hour fighting a blaze in which 907 kilos of marijuana went up in smoke.

But they breathed in so much marijuana smoke that they would have failed a drug test, according to Fire Chief Shawn Snider.

He added that this was despite wearing air packs to prevent them from inhaling toxic or hazardous fumes.

Source: MetroUK

Neighbor Conflicts
North Boulder Neighborhood

A commercial grow operation in north Boulder, Colorado has been emitting a "constant and very pungent" marijuana smell that affects more than a block of nearby houses.

Even after months of efforts by the city, complaints from neighbors and $14k in fines, the building has still not come into compliance with regulations.

Even supporters of legalization are upset about the pollution.

"It's like a really stinky skunk smell," said Heidi Davis, a neighbor who supports the marijuana industry, but has been complaining about Dandelion to the city for a year, because "you can't even really sit on your deck sometimes, it's so strong."

Source: Daily Camera

Next Door to a Home Grow

The Parker Chronicle in Colorado highlighted the story of a man whose neighbor started a home-grow operation.  The operation sends a constant marijuana smell into the neighborhood.

“It's unbearable,” said James, a neighbor who asked that his last name not be used because he said he fears for his family's safety. “For my kids, it's uncomfortable to play outside.”


...His 11-year-old daughter, who likes to swing in the front yard and take her cat out to play in the grass, said the smell coming from the home gives her a headache and a cough, which makes her not want to go outside anymore.

“It makes me sick,” James said. “I never thought of the possibility of a grow operation in my neighborhood.”

Oregon Apartment Complex

In Oregon, several neighbors made complaints about a marijuana smell coming from one apartment.

One person told the officer "that the smell was especially difficult for him because he was currently attending rehabilitation for drug abuse and the smell of marijuana was a 'trigger' for him," according to the appeals court summary of the case.

Another neighbor said that he'd lived in his unit for eight years and that "the neighbors in the middle rental (had) gotten worse and worse," according to the summary. Two more neighbors said they smelled pot coming from Lang's unit two to three times per a week.

The police got a warrant to search the residence, since offensive smells can be deemed "disorderly conduct."  However, an appeals court ruled that the warrant was not justified because the smell of marijuana is not "physically offensive."

The court conceded that, "At some point, the smell could be considered offensive to a reasonable neighbor, especially if the neighbor is in the sanctuary of his or her own home."

Source: The Oregonian

In our UWS high rise apartment, we have neighbors who really, really enjoy marijuana. As soon as we get off the elevator, we are bombarded by the smell in our hallway, and it frequently wafts its way into our apartment.

My husband and I don't want to be complete squares, but it's getting worse and worse, and we're trying to get pregnant (so a contact high is not a good thing!).

The letter writers were advised that they should contact their landlord, since the police would not prioritize the problem.

Neighboring Apartments in NYC

The New York Daily News addressed a question from people bothered by marijuana smoke in their apartment:

Four-Plex Neighbors in Denver

This anecdote from the Denver Post illustrates the potential for neighbor conflict. It points out that there is no law protecting residents from secondhand marijuana smoke.

Kat Haig had finally had enough.

Enough of the downstairs neighbor in her four-plex building in Colorado Springs smoking marijuana “like a chimney.”

Enough of the all-too-distinct-smelling smoke filtering up, somehow, into the apartment she shared with her son and daughter, ages 6 and 3.

“It was to the point where my kids were asking, ‘What is that awful smell?’ ” said Haig, 27. “It was pretty bad. It was strong.”

...And now, with marijuana legal for adult recreational use and more available than ever, weed joins the list, whether it’s smoke wafting in your windows or a pungent grow operation next door.

You may find it offensive, but that neighbor lighting up a joint in his or her backyard is likely not doing anything wrong, legally speaking, as long as they are at least 21 and on their own property.

“It’s like smoking a cigarette — if you’re on your back patio smoking a cigarette, you’re not doing anything illegal,” said Steve Davis, spokesman for the Lakewood Police Department.

“Someone is doing something that’s legal on their own property,” he said. “We don’t always have the authority to do anything about it.”

Source: Denver Post

People Share Their Stories
Health Effects on Bystanders
Contact Highs
Neighbor Conflicts
People Share Their Stories
Our Position on Secondhand Smoke
Discomfort and Harm to Pets

When exposed to sufficient marijuana smoke, dogs and cats become depressed and disoriented. They lose muscle control and become wobbly and incontinent. They experience tremors, weakness and hypothermia. Their eyes become glassy and dilated. These symptoms can last up to 72 hours.

According to veterinarian Jean Hofve:


With the new, stronger pot strains, there’s a risk of increased excitability, high fever, tremors, seizures, and possibly coma or death. Deliberately exposing pets to pot smoke may also be considered abuse under most state laws.

Potential Harm to Lungs

Secondhand marijuana smoke contains many of the same toxins and carcinogens found in directly inhaled marijuana smoke, in similar amounts if not more. While there is no data on the health consequences of breathing secondhand marijuana smoke, there is concern that it could cause harmful health effects, especially among vulnerable children in the home. Additional research on the health effects of secondhand marijuana smoke is needed.

Exposure to Harmful Chemicals

A 2008 study found that secondhand marijuana smoke contains "known carcinogens and other chemicals implicated in respiratory diseases." 

In this study, secondhand marijuana smoke contained three times as much ammonia as secondhand tobacco smoke and about 400 times as much ammonia as mainstream tobacco smoke.  It also had higher levels of tar, nitrous oxide, hydrogen cyanide, acrylonitrile, aromatic amines, butyraldehyde, polyaromatic hydrocarbons and "miscellaneous organics" such as benzene and toluene than were found in mainstream or secondhand tobacco smoke. 


On the other hand, secondhand marijuana smoke had lower amounts of carbon monoxide and phenolic compounds than were found in tobacco smoke.  It also had lower amounts of most carbonyl compounds than were found in secondhand tobacco smoke, though those amounts were still higher than in mainstream tobacco smoke.

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