In the drive to prevent early deaths from respiratory diseases worldwide, health experts focus on curtailing exposure to proven causes like cigarette smoke.

Now, research in the journal the Lancet shows early childhood illnesses exert a strong influence as well.

After controlling for socioeconomic factors and smoking exposure, this 73-year study of almost 3,600 people finds having infections like bronchitis or pneumonia by age 2 doubles the risk of dying early from respiratory disease as an adult.

Such infant illnesses could potentially cause one in five premature deaths from respiratory disease, compared to three in five from smoking.

 Research also links early lower respiratory infections to adult lung impairments, asthma and COPD, which causes most chronic respiratory disease deaths.