Astrophysicists fall into either the fire or ice camp when it comes to deciding the fate of the universe. Will expansion continue until everything flies apart into a state of absolute zero, or will the Big Bang reverse itself into an unimaginably fiery Big Crunch? In the social sciences, the big debate is whether nature or nurture reigns supreme in shaping human behavior.
In our industry's little corner of the world, a similar dialectic lurks in the background over the cause of Legionnaire's Disease (LD). My guess is that upwards of 90% of plumbing engineers accept the conventional scientific wisdom that the culprit is the Legionella pneumophilia bacterium. However, it's hard to completely shake a 25-year-old theory that the disease is caused by phosgene gas resulting from the breakdown of refrigerant gases at elevated temperature. It's bugs versus gas, plumbing vs. air conditioning, nature vs. man-made in the quest to identify the villain.