There's never been a single case of BrOb from smoking
That's not exactly correct. Per our good doctor, from the old thread we both read:
The incidence of COPD in smokers is up to 15%. The incidence of bronchiolitis obliterans by diacetyl exposure is extremely low. In fact, only few cases have ever being documented. Most commonly, diacetyl exposure causes a decline in lung function which can be detected by a reduction in FEV1. This is much more common that development of bronchiolitis obliterans. However, this can be easily misdiagnosed as COPD."