KN95 face masks are the most effective in stopping germ spread – breathing through a scarf is not – according to bacteria festering in petri dishes in a Northland Year 7 student's family home.
Kamo Intermediate School students Bella Monteith and Camryn Collinson decided to carry out an experiment for their school science fair testing various means of stopping airborne germs spreading while talking, coughing and sneezing. That was back in March and their experiment qualified for the regional finals originally planned for this week, which will now be held online.
Their experiment involved one person – Bella's dad Greg, who was asked to talk, using multiple "t" sounds, do fake coughs and sneezes and sing "Happy Birthday". He conducted this routine six times; while wearing a KN95 mask, a blue paper mask, a fabric mask, a scarf, social distancing and with no mask. A further test was carried out with a control dish.
The experiment was carried out twice over two weeks and the petri dishes, which contained the jelly-like substance agar, which bacteria feed on, were kept in a chicken incubator and monitored daily. The growth rate was depicted on a graph before a conclusion was drawn at the end of the week.
It showed the dish from the KN95, with its 95 per cent filter and being the thickest mask, contained little bacteria or fungi and was determined the best mask to block the spread of germs.
The blue paper mask ranked second with little growth, and was a cheaper option, and the fabric mask had several dots of bacteria or fungi and a large colony of growth and was not recommended. The scarf had a large bacterial or fungal growth and was also not recommended.
The social distancing results turned up a large bacterial or fungal growth similar to the scarf but proved better than the "no mask" experiment, which showed a lot of bacteria or fungal growth "which is yellow and large". The control dish showed minimal bacteria growth but that there were still bacteria in the air.
Bella's mum Abigail said that while the girls' experiments were based on just one person and environment, they were reflective of what the science and health authorities were recommending.
"The results are interesting, but probably what you'd expect – which is reassuring to know face masks do work well, face coverings not so much."
Bella said: "When we did the science experiment, we didn't know how relevant it would become. What we learnt is that face masks do work at stopping the spread of bacteria. I hope our project can help people understand how the masks work and which one is the best."
Added Camryn: "After doing this project, I understand how easily bacteria spreads from person to person and how a mask can help. I'm happy that our regional science fair will still be happening online this year – it was meant to be at Forum North this week – so we can present our work."
While Greg had been a good sport, the experiment had provided some amusement for those involved. Meanwhile, the petri dishes with their bacteria which, Abigail confirmed smelled like chicken, were being stored in sealed bags in the home office awaiting their debut at the now redirected Central Northland Science and Technology Fair online. For more information on this go to: https://centralnorthlandsciencefair.co.nz.