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"Bring science home" all
撰文 | Skin
Recently, a man in Kumamoto, Japan, "blew up" his house while killing cockroaches, and when the police arrived, they found that the balcony glass had been shattered and people were slightly injured.
Coincidentally, in November 2017, there were two serious fire accidents in Ohio, USA, one burning down a six-unit apartment and the other burning down a multi-person home, leaving more than a dozen people homeless. And it's all about getting rid of bed bugs in the house.
Burned a house while using alcohol to kill bed bugs...... Reference 2
Killing a bug and causing a lot of damage doesn't sound like a good idea, but do you really kill an insect? In fact, if you use the wrong insecticidal method, you can "blow up" the whole house because of a bug.
The tragedy in Ohio was caused by people using alcohol to kill bed bugs. Spraying alcohol is a common way to kill bed bugs, but it can also be dangerous because flammable alcohol can quickly evaporate and permeate the space. All it takes is a few sparks to start a fire.
The U.S. Environmental Agency has warned against using alcohol, propane and other gases that do not indicate insecticidal properties to kill bed bugs, and do not use pesticides labeled for outdoor use. When using pesticides, be sure to read the instructions for use and the label on the bottle carefully.
Read the label carefully!|US EPA
In this news from Kumamoto Prefecture, the police investigated and found that the man sprayed a large amount of insecticide in the process of killing cockroaches, and he may have sprayed near the power supply of the heating table, which caused the subsequent fire and explosion accident.
In the aftermath of the explosion in Japan, Japan's Consumer Affairs Center said it had received multiple reports of explosions, all of which were caused by improper spraying of pesticides near household appliances and power sources. Why does the sprayed insecticide explode in this situation, though?
It is very dangerous to use insecticide sprays near the power source |
The insecticidal sprays commonly used in our homes are generally pyrethroids, such as permethrin and promethrin, and there may also be targeted ingredients, such as carbamates, organophosphates or neonicotinoids, which are not flammable.
This insecticidal spray also works on a simple principle, pushing chemicals out of the canister to form a spray that kills insects that come into contact with it, it is convenient, fast-acting, and has been widely used since the introduction of the patent in 1927.
Allethrin is a common ingredient that can damage the nervous system of cockroaches and paralyze them in very low doses.
However, there is not only pyrethroids in the aerosol cans, but also propellants that help these things spray out. Commonly used propellants are generally some petroleum gas, such as compressed liquefied propane or butane.
When the valve of the compressed spray can is opened, the pressure inside the tank decreases, causing the pressurized liquid to form a gas layer in the upper half of the can, pushing the liquid from the lower layer out of the can. As the liquid flows through the nozzle, the propellant also rapidly expands into a gas due to the decrease in pressure, allowing the liquid to atomize and form a very fine spray. In this process, petroleum-based gases may account for up to 40% of the spray volume.
Petroleum-based liquids are often used as propellants in aerosol cans. ｜aerosol.com
These petroleum-based liquids pose a certain risk. Dangerous accidents can occur if the spray is left in direct contact with an ignition source, or if it is an indicator light, power supply, and electrical appliance that generates electric sparks.
The insecticide bottle and various usage guidelines will remind you not to expose it to open flames, and the U.S. Environmental Protection Agency also advises that this insecticide should be used or placed more than 2 meters away from fire. In 2019, a woman in Beijing tried to kill cockroaches on a gas stove with spray insecticide, resulting in a serious explosion and casualties.
Flammable sprays should not be sprayed too much. Especially in confined spaces, the concentration of flammable mist is too high, which is also very dangerous. In Japan, an occupant turned on the light switch after cleaning his room with a spray, and an invisible electric spark suddenly detonated the room, causing facial and respiratory burns.
In general, the dosage used may be written on the bottle of spray insecticide. ｜giphy
In New Jersey, USA, in 2016, when a resident sprayed insecticide to get rid of cockroaches, he felt that the insecticide smelled too much, so he opened a window to ventilate. According to investigations at the time, the flammable mist then came into contact with the sparks produced by the furnace, and the air outside the window provided just enough oxygen, causing a severe explosion. The door frame of the house was bent by the blowing, the kitchen was damaged, and two adults and a child in the house were injured.
A resident used pesticides in the kitchen, causing a serious explosion. | Reference 3
Not only insecticides, but other sprays also need to avoid dangers when using them, as they may contain petroleum-based propellants, such as hair leave-in sprays, sunscreen sprays, cooling sprays, spray paints, etc......
You may have also heard many cases of spray cans exploding on their own, and in high temperature conditions, spray bottles that are originally under high pressure inside are likely to explode on their own. For example, in the summer, the spray placed in the car detonated an entire car.
All types of aerosol cans need to be careful not to be near fire sources and high temperatures. ｜Flickr
In addition, the environmental authorities of various regions have also warned that aerosol cans can also become dangerous garbage and explode during waste transportation and disposal. You need to make sure that you empty it thoroughly before throwing it away, you must observe the garbage classification, and you can't poke the can yourself!
In January 2023, an explosion occurred at a recycling centre in the UK due to the fact that the garbage contained an unemptied aerosol can. Reference 4
Today, however, new technologies are being used to avoid this danger. For example, the current "binary spray" is to separate petroleum-based gases from useful components to avoid the discharge of flammable gases. Some manufacturers have also started using non-flammable boosters. However, before these products are officially launched, what we can do now may be to learn Xi proper use of aerosol cans.
When using spray products, you need to carefully read the precautions on the bottle.
Resources:
[1]https://mainichi.jp/english/articles/20231211/p2a/00m/0na/006000c
[2]https://www.cbsnews.com/news/cincinnati-ohio-woman-burns-down-home-trying-to-kill-bedbugs/
[3]https://www.abc.net.au/news/2018-03-08/insect-spray-flame-thrower-causes-explosion-in-mt-isa-kitchen/9526452
[4]https://uk.movies.yahoo.com/watch-terrifying-moment-aerosol-explodes-150000610.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAALWCgcyObZT2qCgDH8faGLjxC_ZYxxr32iihC0Tr2mNiBW7Y_jlEGN_-fiGsN9G3z2PmDqA3XUZOwyVdbrYzrFnV6OvWkMxMUEaQqe5vaiLXPPjGmU9YOa9saGrAYMjXyfF4SXRP8cvTwcSv0HtFgUhB_wmMGrFLu1KPAyzWZ_wk
[5]https://www.cincinnati.com/story/news/2017/11/29/boy-trying-kill-bedbug-sets-fire-causing-300-k-damage/904324001/
[6]https://www.epa.gov/safepestcontrol/safety-precautions-total-release-foggers
[7]https://piyao.kepuchina.cn/h5/rumordetail?id=eXWE
[8]https://www.epa.gov/bedbugs/stay-legal-and-safe-treating-bed-bugs