Quit bugging me! What’s in that water mist?

Posted on


As soon as I arrived in San Antonio it was clear to me that the weather here is pretty awesome. I’ve been soaking it up and enjoying the sun while eating out at the many bars and restaurants on the lovely Riverwalk.

The other day while I was chowing down to breakfast, I was asked by the manager of the cafe if our group would like to have the “coolers” turned on. These “coolers” were fans with water mist tips that created a fine mist that was blown over us to keep us cool during our meal. Great idea and it worked. Since then I’ve also seen a string of restaurants that just had mist sprays across the whole of the front of their premises.

While being an occupational hygienist is great when you are at work, it can be a drag when you’re on a break, as you find your brain not being able to switch off “hazard” mode. I quickly thought, “what about bug control in these waters?

You see, you can contract an illness from breathing in mist from water that contains certain bacteria. That illness causes high fever, chills, cough, and sometimes muscle aches and headaches, and can be life-threatening. That illness is known as Legionnaire’s disease, and it is caused by legionella bacteria.

Legionella is common in natural water sources but usually in low numbers, however given the right conditions, the bacteria can multiply and start to cause issues. The HSE UK explain that those conditions include

  1. If you have a water temperature somewhere between 20–45 °C
  2. If it’s possible for water droplets to be produced and dispersed
  3. If water is stored and/or re-circulated
  4. If there are deposits that can support bacterial growth, such as rust, sludge, scale, organic matter and biofilms.

So I started to ponder if all of these conditions existed while I was eating my breakfast fajitas. In this case, I was sitting under a water mist that was around the right temperature for bacterial growth, which came from little black pipes (some of which had dead legs in them), and some sections of the system looked pretty old…so most of the ingredients existed for a potential problem. However, these coolers did seem to be running most of the time, and I’m assuming (hoping) that the water was sourced from mains water supply, and not from tanks out the back somewhere being a breeding ground for more potential problems.

I admit that I didn’t take any water samples, and I didn’t conduct a thorough risk assessment of their water systems (I’m the social guy remember…I was busy being “social”!), but it is a hazard that if not controlled properly, has the ability to result in a major public health issue. It also shows another way that occupational hygiene has found a way into something in our daily lives.

If you need some information on controlling legionella bacteria in water systems, then the HSE UK has a great guidance document here.




Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s