Chlorinated Solvent

There are some things in occupational hygiene which make our job harder: politics, money, personalities, fiction (not facts), rules/laws and schedules.

However, there is one person who we can blame. Maybe not entirely, but he epitomizes the opposite of protecting people’s health. Thomas Midgley, Jr. Who? Yea, he’s new to me too. Thomas Midgley

This guy has killed millions of people. Maybe not directly, but through his politics and lack of ethics. Here is a great article from Seth Godin on this guy. Essentially he allowed lead to be added to gasoline, AND, helped to provide CFC (chlorofluorocarbons) to products. However, he probably got what he deserved: He died from his inventions. It is easy to look at hindsight and blame him, but at the time, I wonder what he was thinking? My guess is money.

The enemy of Occupational Hygiene is probably not Thomas Midgley. It’s our ethics. If we fail to make the right choice every time, where does that lead us?

If you’re reading this, you probably don’t suffer from an ethical-failure to protect people. (Most people in safety don’t.) Rather, you should pat yourself on the back and keep doing the right thing. Good job.


I’m easily impressed with welding and welders. Welding looks so simple, yet hard, dangerous and permanent.

When interviewing your welder, here are some questions to ask:weld1

  • What type of welding are you doing?
  • What type of metal do you weld on? (mild steel, stainless, galvanized)
  • Is there any coating on the metal?
  • What type of flux is used?
  • Where do you weld?, and then, “Where else?”
  • Is there any ventilation in the area you weld?
  • Are there any flammables in the area?
  • Do you wear any PPE when welding? (ear plugs, respirator, leather)
  • When do you use fall protection?
  • Do you have & use welding shields?

What makes welding so difficult is the number of variables involved. The welding variables can change by the minute. Educate your employees on these dangers.

After the above questions, if the employee is agreeable, I ask some additional questions. These are the ones that provoke the best stories:

  • What is the strangest things you’ve welded?
  • Have you ever welding in a really small (confined) area?
  • Have you ever welded with exotic metals? fluxes?
  • What’s the worst thing you’ve welded on?
  • Have you ever gotten sick from welding?

There are many, many more questions to be asked depending on the answers. The authority on this subject, Michael Harris, has written an excellent book on this subject, “Welding Health and Safety“(ISBN 978-1-931504-28-7). It is available from AIHA. It is VERY detailed, and money well spent if you do welding. I have taken his short course (all day) and I learned more than I ever thought possible, and I still can’t even weld!


Sometimes the perfect storm happens and the situation seems so innocent.  Here are the variables:

  • A new shop with a great ventilation system- the airflow moves from Bay 1 to Bay 5 in rapid succession
  • Bays 1-4 are mechanics who occasionally work on heavy equipment/ vehicles
  • Bay 5 is for welding- has local exhaust and ventilates directly outside


  • Welder usually does maintenance – small jobs
  • On one particular day he is laying down A LOT of wire- and preheats the metal
  • Same day- a mechanic needs to clean some parts and uses a cleaner found in most mechanic bays
  • Welder “smells” something unusual- get tightness in his chest and almost passes out

What occurred was the perfect combination for a deadly situation. Chlorinated solvents, when their vapors are heated, can form phosgene.

Here is a link to the CDC regarding phosgene. Abbreviated as CG by the military- since it was used in WW1 as a weapon.