The rotten egg odor was a result of attempting to clean up automotive exhaust via catalytic converters. Before that (1974 for most makes, Honda being one of the few exceptions that I'm aware), automotive exhaust from gasoline engines really didn't smell all that bad.
What really has changed is widespread, tightly insulated houses, with the windows seldom being opened due to air conditioning. And, those houses went to wall-to-wall carpeting at about the same time. Drywall board replaced mold-inhibiting lime plaster, too. Several variables there, that could be a culprit. Video games and cable tv keeping kids inside aggravated the situation, all manner of behavioral changes associated with climate control.
Throw open your windows, turn off the tv and computer, get your kids outside at an early age. Let them get a little grubby as kids are wont to do, get a couple of pets. Epxose them to allergens while their immunity is still forming, and these several allergies won't be quite the issue that they are now. I recall only one person from my childhood with asthama, and pitied him. It's almost endemic now.
The rotten egg odor was a result of attempting to clean up automotive exhaust via catalytic converters.
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I was thinking more about the rotten egg odor that came from industrial sources, particularly coke plants.