Residents of Nailsea, a British town near Bristol, had a somewhat unusual end to 2018. People were forced to evacuate their homes last Thursday after a noxious gas cloud erupted on their street. 

The good news is that this was not a pre-planned chemical attack targeted at the people of Nailsea. Rather, it turned out to be a simple cleaning accident by a woman attempting to unblock a toilet. 

Dominique Heath, a mom of three, had the unpleasant task of unclogging a toilet on the day after boxing day after one of her children blocked it with a toy or too much paper. In the afternoon, she filled it with two bottles of a toilet unblocker and left it to do its job. But at 8pm, it was still clogged. And so she added a 3-liter tub of bleach to the mix. For the record, that is a lot of cleaning solution.

Unfortunately for Heath, the chemicals in the toilet unblocker and the bleach reacted to form a putrid cloud of chlorine gas, a poisonous substance so toxic it is banned by the Geneva convention and its use is considered a war crime. In small doses, it can cause skin and eye irritation but too much of it can lead to chemical burns and breathing problems. In the very worst cases, it can result in noncardiogenic pulmonary edema (build-up of fluid in the lungs), which can be lethal.

Undoubtedly a little concerned about the foul-smelling gas, Heath told Bristol Live she shut the bathroom door and opened up all the windows in the house.

"I have never experienced fumes like it," she said. "My throat and eyes feel burned."

The cloud continued to spread so she turned to a neighbor for help and called the fire service, who immediately told her to evacuate. They then sent fire crews from three separate stations in the Bristol and North Somerset area to attend to the chemical accident and cordon off the end of the street until it was safe to return.

Since the whole affair came to a close, Heath has shared her story on Facebook saying she wants to use her experience as a warning to anyone else who might be tempted to mix large quantities of potentially lethal chemicals. 

"It was really serious," she said, Bristol Live reports. "We are all ok, but it was the dumbest thing I have ever done – please don’t do this!"

It's not the first time a chemical experiment has gone awry. Last year, a school in India had to be evacuated after a "make your own volcano" experiment exploded, and in 2017, several Australian students had to be rushed to hospital due to chemical contamination. Another incident saw 500 students vacated from a university library due to a suspected gas leak (the stench was actually caused by a foul-smelling fruit).

Fortunately, this time it appears no one was hurt.

[H/T: Bristol Live]