This report, that cigarette smoke (CS) but not Ploom TECH or Ploom TECH + HNB products causes apoptosis and a change in transcription-related histone modifications and is highly correlated with upregulation of EGR1, suggests that CS, but not HNB products, causes COPD via apoptotic mechanisms. The gene discussed is EGR1; the disease is chronic obstructive pulmonary disease.