Did a skunk set off my smoke detectors?

O.K., the other morning, at 0-stupid-thirty, the two smoke detectors went off briefly. It happened again, about a half hour later. They sounded for 3 or 4 seconds. This was two days ago, and I’m now quite certain that the house is not on fire. The only thing out of the ordinary that I know of, is that all the windows were open, and I had trouble sleeping because a skunk had obviously exploded right outside. If I didn’t know any better, I’d say a whole army of skunks were pissed off at my house-it was pretty bad. So, the question is, could it be that pepe’s perfume set off my detectors?

No sure how skunks could set off a smoke detector. SD work on two principles; light beam and ionization chamber. I doubt either would be affected by skunk odor, but I suppose it’s possible that it would have some effect on the ionization chamber.

friend chandeleur,

are your detectors powered by the 120 volt house current? if they are, a power brownout could cause them to chirp at the restoration of power.

smoke detectors do not detect odor, but particles of products of combustion. a photoelectric detector reacts to visible smoke more efficiently than an ionization detector, which better senses non-visible products of combustion.

the skunk may smell horrible, but i don’t think the particle size of the odor would be large enough to set off your smokes.

is it real humid where you are? humidity has an effect on ionization detectors and can make them more sensitive, and more prone to false alarms. are there smokers in your house? tobacco smoke is hard on detectors. are the screens around the openings in your detectors dust coated? many false alarms are caused by dirty detectors.

if you have two detectors that falsed at the same time, i would suspect the drop in the current that powers them. for two detectors, widely separated, to trip at the same time is unlikley.

if there are any doubts about your detectors, replace them. if they are more than five years old, replace them anyway. if they are battery powered, or have battery as a backup power source, replace the batteries today. while you are at it, check the status of your carbon monoxide detector too.

longhair75, (state fire alarm inspector’s license #476, installer’s license #0586)

This may not be pertinent, (and don’t ask me how I know this) but…

There are some substances that are not fire related that will readily set off an ionization type fire detector. Some of the fuel gases will set them off. I don’t think butane will do it, but propane may.

Military style CS riot control gas is one of these substances. Even in concentration so low that it is practically undectable to a human nose, it will set off the fire detector.

CS is a compound designed to be irritating to be around. Skunk scent has a similar purpose. I am sure they are pretty different chemically. While this is far from proof of what happened, It does make your theory more plausible.

There is a rather easy way to find out for sure. Many good hunting stores carry real skunk scent in a bottle. You could get some and give a detector a little whif and see if it goes off. Be careful, you do not want to spill this stuff. In fact, I would recommend moving the fire detector into your garage or something to conduct this test.

Bottom line is that any substance in the air that can absorb ions will set the detector off. Combustion products are known to do this, but many other things do as well.

Skunk scent is made of very large aromatic hydrocarbons. It seems entirely reasonable that it could set off a fire detector.

The detectors are indeed hard-wired. This was my first thought, however here in rural Maine, the power goes out all the time. Everytime the power had dropped, even so quickly we hadn’t noticed, a few things happen: 1. Computer turns off 2. Microwave, and all other electric type clocks are reset. 3. CO detector beeps 4. Fire alarms do not go off. They may chirp, as you said, but these detectors the other night went off. There were no indications that power was interupted.

It is very humid here this time of year, and that night was no exception. There are no smokers in the house, nor has there ever been. The detectors are free of dust, having been cleaned 4 months ago when we painted.

My first thought was power, but all surrounding facts lead away from that idea. I’ve been smelling skunks here in Maine regularly for 4 years now- they are very common. This night, however, was bad. That skunk may very well have been smoking a cigar on my couch, getting pissed off at the cats and dog.

scotth: your idea intrigues me. I believe a controlled experiment in the name of science is in order here. Actually, I would just have to take a SD with me to work, and stop at any one of the dozen or so roadkill spots along my way everyday!

That is pure science right there.


You had a physical process you don’t understand. (The fire alarms are going off, but why?) You come up with a theory that fits the evidence. (You think a skunk might be setting them off.) Nobody really knows but it seems possible. You can think of an experient that would nearly prove your theory right, or be able to certainly prove it wrong. (Exposing the detector to skunk deliberately and see if it goes off each time it is exposed.) You do the experiment and find out if you were right or wrong. If you were wrong, you scrap that idea and guess a new one. If you were right, you are pretty happy about it, and maybe some new piece of information would come into this world that nobody new before.

Our smoke detectors (only two years old) went off this evening immediately following a bad skunk spray right outside of our house. The windows were open and we were just starting to close them as the alarms went off. There could be something to this skunk/smoke detector thing…

zombie or no

i’ve never heard of odors (from non-fires) triggering.

there is only one way to test this out. somebody with a live cage trap that has frequent skunks needs to trap one. then put a battery powered detector on the end of a 10 foot science pole and approach the skunk with it. see what happens.

But, as I said nearly 10 years ago when this first came up, you’d have to provide a mechanism that would explain it. Right now, there doesn’t seem to be one based on the design of smoke detectors.

Zombie skunks, that could be a problem.

No you don’t, you just need an experiment showing it happens. Then you come up with an explanation, then test that.

How about a house containing 36 dead cats and the police chief saying the stench may be what set off the fire alarm that alerted them to it?

Carbon monoxide detectors are definitely known to have false alarms from strong odors and a lot of smoke alarms have CO detectors built-in, so that is another possible explanation.

There does seem to be a sort of plausible path. But since I’m not a chemist, I really don’t know enough to say one way or the other. Even a lot of chemists probably would need to crunch some numbers here.

An ionisation smoke detector works by setting up a chamber where a constant supply of alpha particles ionises the air, and a tiny, but measurable current is able to pass across the chamber. Enough smoke particles entering the chamber will attract the ions, scavenging them out of the air, and the current will drop, triggering the detector.

So, is there something in the skunk odour that is peculiarly special that can scavenge the ions in the chamber in a manner that most other things we have in the air will not? Well maybe.

Use of alpha particles means that the ions in the air are going to be positively charged.

Skunk odour seems to stem from a cocktail of thiols. Thiols contain a sulphur atom, and are particularly nucleophilic. This means they donate electrons easily, and it would seem that they may be exactly the sort of thing that can scavenge positive ions out of the ionisation chamber.

To investigate this correctly, will you please post a picture of the smoke detector ? or make/model number ?