I am renting an Airbnb in South America. To kill cockroaches, the owner put a fine layer of white powder (from internet searches, I believe this is either borax or diatomaceous earth) on the floor yesterday morning. It is hot, so I always run a fan on high (over my bed) which probably kicks up some of that powder.

I woke up this morning with a dry mouth, throat, and nose, so am concluding that this is due to my breathing in the powder. When I blew my nose, I could even see dried blood. There seems to be a chalky taste in my mouth too, but that might be psychological.

By the way, I have seen maybe 10 dead cockroaches, so I know the powder is working.

From a quick blow test, this powder did not lift up from the ground easily (I think baby powder lifts much more easily), so maybe I did not breathe in very much. The white particulate's size and weight might be enough to keep it on the ground.

Is it generally considered bad to use a fan in a room with this powder treatment?

I am thinking to switch off the fan, let any dust settle for an hour, and then mop my entire floor before sleeping tonight.

In hindsight, I think I should have refused this treatment though I wasn't really given the option. If anyone has medical studies or anecdotes about the health effects in my case, can you please reference them? I'm trying to stay neutral, but if it's well-known that this is hazardous, I want to let the owner know.

  • 1
    Seems like this would be a better fit for Biology, since it's about the medical effects of the cockroach killing powder, however, reading their on-topic list doesn't seem like it would be a fit there, either. Same for Medical Sciences. Not really sure this is on topic here at DIY/Home Improvement, either...
    – FreeMan
    Jan 21, 2021 at 14:56
  • I would suggest that you find a broom or vacuum and get rid of the powder in the sleeping area, but leave it elsewhere. This will minimize the dust in the air when you're sleeping, but still kill as many roaches as possible. Presumably (making a gross generalization) you're on vacation of some sort so you're not spending loads of time in the place during the day - you're out seeing the sights, so daytime exposure won't be a significant issue.
    – FreeMan
    Jan 21, 2021 at 14:57
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    In South America there is no telling what pesticide may have been sprinkled on the floor.
    – Kris
    Jan 21, 2021 at 15:23
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    Diatomaceous earth, at least, should be placed outside the house where bugs get in. It works by cutting up the soft underbellies of insects with the desiccated exoskeleton pieces of other dead insects. Basically like army-crawling over a bed of nails. But it's still "earth" and thus it would be odd to use it inside. This is probably Borax or some other artificial pesticide.
    – TylerH
    Jan 21, 2021 at 17:18
  • Borax is soluble, diatomaceous earth is not. test them. The diatomaceous earth might also have an insecticide added to it. Jan 21, 2021 at 21:39

1 Answer 1


Borax and DE are a low coast and easy way to eradicate insects. They both are a less toxic form of killing bugs. DE is the remains from a prehistoric sea mollusk (the shell I believe) while Borax is a natural occurring mineral.

Borax should not be applied where it can get accidentally inhaled or absorbed by humans and non-target animals. Although it is less toxic than other insecticides it is not inert and can have harmful effects if ingested.

DE while having no toxic ingredients also cause problems due to it's shape. The fine powdery dust that is DE has extremely sharp ,albeit minuscule, edges. If enough is inhaled it can cause possible lung problems.

To haphazardly spread either of these substances while considering them safe, is both reckless and unsafe. If you'd rather not tempt fate and sleep easy purchase a trap-like product (like "Roach Motel" etc.). These products either use a lure phernome that entices the specific bug to enter the enclosed trap where upon it gets stuck on the sticky floor or a chemical bait that it ingest's and dies. This is the safest way to ensure you and pets are safe and insects are eradicated quickly.

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    DE is the remains from a prehistoric sea mollusk ... DE is the remains of diatoms ... they are single celled creatures ... a type of algae ... duckduckgo.com/?q=diatoms&iax=images&ia=images
    – jsotola
    Jan 22, 2021 at 0:48
  • It's impossible to use borax without breathing some in, so it would be good to give a measurable limit. I would assume they might even design these products to not lift and move with a fan, so maybe I'm ok...I still don't know. Anyway, I mopped up most of it, so hopefully I don't have the same problems tonight.
    – bobuhito
    Jan 22, 2021 at 3:14
  • Just "less toxic"? that's misleading AF. the LD50 of borax is the same as table salt; it's an ingredient in food and toothpaste. I use it to cure athlete's foot with one treatment. It's not toxic, at all. Some people even swear that eating it helps arthritis. I don't know about all that, but it won't hurt anyone or pets when used as a pesticide.
    – dandavis
    Jan 24, 2021 at 10:53
  • here is a quote from Medical News Today: "Borax is not safe to ingest. According to the NLM's Toxicology Data Network, borax is easy for the body to break down when either inhaled or swallowed. However, if inhalation or ingestion occurs, both serious poisoning and organ damage can result." Any google search will show its dangerous (AF)
    – ojait
    Jan 24, 2021 at 16:04

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