Can eCigs Set Off Smoke Alarms?

The first step to answering this question is first to learn more about smoke detectors and how exactly they work. 

Francis Robbins Upton who worked with Thomas Edison was the first person that patented the first fire alarm system in 1890. His version was triggered only when the temperature of a room got too high. That is why the first true smoke detector is said have been invented by an Englishman named George Andrew Darby in 1902. Working off of Upton’s original design he tweaked its sensing ability so that it would also include the particulates from smoke in order for an alarm to sound, not just temperature. Expanding on Darby’s design, another inventor named Walter Jaeger wanted an alarm that would detect poison gas when it is in a dangerous quantity in a certain environment. He experimented with many designs and used a lit cigarette as a testing subject and soon enough was able to invent the first ionization smoke detector.  But the first truly affordable smoke detector was not made until 1965 by Duane D Pearsall whose model featured an individual battery powered unit that could be installed and replaced easily, and thus the modern fire detector was born.

There are two types of smoke detectors; they differ only in how they work. The two types are optical detection (photoelectric) or by physical process or ionization—it should be noted that more modern smoke detectors nowadays use both methods.

Optical Smoke Alarms:

Optical detectors are basically light sensors. They use beams of light to detect the presence of smoke particles in the air. If there is smoke being emitted from a fire, the smoke will funnel into the chamber of the optical alarm and will block off the infrared rays being produced by the alarm inside its chamber. The alarm senses that there are particles blocking the light rays and will then trigger its sounding alarm to notify the occupants that there is smoke in the air.

Where they are used:

Optical smoke alarms are most commonly found in industrial, commercial buildings and establishments.

Ionization Smoke Alarm:

An ionization smoke detector uses a radioisotope to produce ionization (when an atom or molecule gets a positive or negative charge if it gains or loses an electron, which forms ions) in the air. When smoke gets into its chamber and prevents this ionization from occurring (smoke particles prevent the ionization), that is when the noise alarm is triggered.

Where are they used:

Ionization alarms are the ones most commonly found in the usual household.

So can the vapor from ecigs set off smoke detectors?

The Final Answer:

From all our research conducted we found the answer to be: Usually NO but sometimes YES. This answer of course is completely dependant on the type of detector that is being used in the building. NO for Ionization Alarms; as explained above, ionization detectors look for smoke particles in the air and with vapor, there is none. But YES for Optical Smoke Alarms; a big enough plume of vapor blown directly into the direction of an optical alarm can definitely set it off because the thick vapor can momentarily block the beams of light inside the chamber, which will then set off the alarm.

Need more info on the subject? Here are forums discussing the topic along with personal user experiences

Stack Exchange: Can ecigarettes / vaping set off smoke detectors?

eCigarette Forum: Can the Vapor set off a smoke detector?

eCigs Subreddit: Do vapes set off smoke alarms?

User Review (S2V4) via YouTube: Does an eCig set a fire alarm off?

But please take heed:

As mentioned above a lot of more modern smoke detectors utilize both of these methods to have a more accurate reading and to ensure the safety of the household’s occupants. If you are vaping indoors and do not know what type of fire detector is above your head, there is still a chance that you can set it off if you are a cloud chaser and love creating huge plumes of vapor.

If you are in your own house, then go ahead please vape freely! If you are worried about setting the alarm off in your home, keep a fan on underneath the detector or vape somewhere that is far enough away from the detector so that your vapor will dissipate before it has the chance to flow into the detector. As we all know the vapor dissipates quickly, unlike tobacco smoke.

But if you are in a public establishment, please check with the manager first if it is even okay for you to vape, or even better just step outside instead of worrying if you may set off the alarm in the first place. You are a walking billboard for the vaping community, it is always best to err on the side of caution and NOT vape if you aren’t sure if it is okay for you to vape there or not.