Talking solar disinfection from Helskini to Highbury

In recent months, courtesy of the IOP, I have had an opportunity to talk about my research on solar technologies for disinfection of drinking water in sub-Saharan Africa to two significantly different audiences.

In March I was a guest speaker at the 51st annual meeting of the Finnish Physics Society (FPS) in Aalto University in Helsinki, Finland. In contrast, in early May I was invited to talk to the year 4 and 6 children in primary schools in London (The Gillespie School, Highbury) and Yorkshire (The Holy Spirit, Catholic School, Heckmondwike) in the UK.

Each audience presents its own challenges. The FPS contain the brightest minds in the country who had gathered to hear of the latest developments in the fields of quantum computing, gravitational waves, photonics and a wide variety of other cutting-edge topics that investigate “what does happen”. On the other hand, the primary-school children were unaware of the restrictions of the scientific method, so let their imaginations run wild with unfettered enthusiasm for “what might happen”.

Any scientist with 28.35g (= 1 ounce) of sense would be nervous about presenting their research in front of such an august body as the FPS, and about the questions they might throw at you. Questions such as:

Are you worried about the possible toxigenic effect of oestrogenic compounds leaching from container material into the water? (We used to worry but the evidence now suggests that the risks are much lower than expected.)

Does the surface to volume ratio determine the optimum kill dose? (We can inactivate any volume up to 20 litres in a single day of good sunshine.)

Has scheduling a cheese and wine function outside the venue during your lecture in a room with a strict no food and drink policy, had any impact on attendance? (I hope not, but who can say?)

In contrast, any sensible scientist (or adult) should be worried about the questions an eight-year-old might stump you with. You can prepare for the FPS presentation and subsequent Q&A. Nothing can prepare you for the onslaught of 40 eight-year-olds brimming with unbridled imagination and enthusiasm.

Questions such as:

Are the bottles safe? (Yes, all the experiments indicate they are.)

How big can your bottles be and still work? (As big as bucket.)

Do you just go home if it is cloudy? (No. Even the small diffuse sunlight that filters through cloud cover can have an effect.)

Why did you become a scientist? (To find out how they put stripes in toothpaste.)

Do you like being a scientist? (Yes. I get to travel all over the world, work with fascinating people, and help them.)

The talk in Yorkshire took an unexpected turn when one of the children asked: “If the Maasai tribes’ cattle poo in the water, making it dangerous to drink, why don’t they just drink the milk from the cattle?”

I responded by telling them how in many East African rural nomadic cultures the cattle don’t produce much milk, are mostly an indication of wealth and are seldom slaughtered for meat. I then made the mistake of adding  that the Maasai sometimes harvest blood from a living cow and will offer it to guests of honour to drink. The questions during the following 10 minutes concentrated entirely on this.

Did they kill the cow? (No, they fired an arrow into its jugular vein, collected about a litre of blood in a calabash and then sealed the wound with mud.)

What’s a calabash? (A type of gourd.)

What’s a gourd? (A type of watertight Maasai jug made from a large hollowed out seed pod.)

What did the blood taste like? (It looked awful and it tasted awful. Full of stringy bits of coagulated clots that got stuck in my teeth.)

Could you have refused? (Not really. It was a huge honour to be part of this ceremony of thanks and to be offered the  blood of their most valued possession.)

Afterwards their teacher confidently predicted that some of her pupils would be going home to tell their parents that they had a talk today from a strange Irish man who drinks blood in Africa – Prof McGuigan the vampire!

However she also predicted that others would be talking over the dinner table later that evening about the scientist who talked to them today about cleaning dirty water with African sunlight. If that is the case, and one among them then adds, “I think I might want to be a scientist” it will all have been worth it. If they say “I want to be a physicist” it will be even better.

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Kevin McGuigan

Kevin McGuigan

Professor Kevin McGuigan is associate professor of medical physics at the Royal College of Surgeons in Ireland and adjunct professor of medical physics with the School of Physical Sciences at Dublin City University.

He is an active researcher in the use of solar energy to treat contaminated water, and a member of the IOP’s Council. He has also served honorary treasurer, chair and vice-chair of the IOP Ireland committee.
Kevin McGuigan

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