Steve’s Insights – Sore eyes! Have a cup of tea

A colleague recently asked me why I had a wet towel on the window ledge of my office dripping water everywhere, I explained to him that wearing contact lenses in the winter months can be troublesome.

The air in our environment is less able to hold moisture at lower temperatures and so when a room is cold, turning on the heating increases room temperature but does nothing to add moisture and as such the relative humidity in the space reduces. This drying of the air causes contact lenses to dehydrate and develop a vice like grip on the eyeball which becomes rather uncomfortable.

As an experienced engineer and contact lens wearer of some years I felt it my duty to investigate this phenomenon and develop a long overdue solution, I set about conducting a number of experiments and I purchased a temperature/humidity sensor to monitor results.


I started with a trick that as a child my mother swore by, it was not long after we had progressed from the daily routine of fanning the fire to a brand new central heating system when she began to notice that the air was dry. This wasn’t because she wore contact lenses or that she had a particular interest in thermodynamics she was simply just sensitive to the environment. Her solution was to place a jug of water on top of the radiator and let it evaporate, this was my first test.

After four hours, barely an egg cup of water had evaporated and the humidity in the room had not budged from its low of 30%. Test two, thinking of my student days I recalled the string of washing in my bedroom which always resulted in everything being damp, so a wet towel must surely be a winner. Once again there was little RH movement on the sensor. I tried opening the window but then realised that the external humidity was much the same as inside.

When all else fails turn to Amazon and after some considerable research I ordered a bespoke office humidifier, although at £9.99 surely it couldn’t be that easy. The parcel arrived the next day and I excitedly set about filling the vessel with water and within minutes a delightful plume of vapour puffed from its top for about an hour before it emptied. Sadly, still no move on the sensor and some basic calcs on a psychrometric chart demonstrated that its capacity was way too small.

It was now time to go big and having seized the kettle from the kitchen I let it boil for 10 minutes noting the conversion of 500ml of water in to steam and finally significant sensor action, an increase from 30 to 38% during the period. However, the success was short lived as within an hour the RH had dropped back to 30%.


This should come as no surprise to an experienced engineer for the same reason that a room will go cold if the heating is turned off, however, I am not sure a permanently boiling kettle in the centre of my office is the ideal solution, not least because no one else is able to have a cup of tea.

It’s a real wonder why the process of humidification has become a thing of the past when clearly a properly designed system can make a significant difference particularly for those relying on contacts.