Environmental tobacco smoke exposure (“passive smoking”) is one of the most common preventable health hazards.  It is associated with common colds, middle-ear disease, respiratory syncytial virus, bronchitis, pneumonia, and serious bacterial infections.  Passive smoking has also been associated with SIDS, exacerbation of asthma, and most recently to behavioral and cognitive problems in children.   It may even be associated with childhood cancers. 

What is the mechanism by which exposure to tobacco smoke can cause infection?  These investigators used a literature review to determine this, and these are their findings: 

Tobacco smoke contains >400 chemical toxins, including nicotine, carbon monoxide, formaldehyde, hydrogen cyanide, sulfur dioxide, nitrogen oxide, ammonia, polycyclic aromatic hydrocarbons, and the nitrosamines.  These substances produce both irritant and immunologic effects on the respiratory tract. 
Nicotine suppresses or inhibits the phagocytotic activity of neutrophils (i.e., digestion by white blood cells of microorganisms and cellular debris).  Nicotine also suppresses production of some immunoglobulins.  Nicotine changes the mucosa of the respiratory tract so that bacteria more easily adhere to the surface.  Tobacco smoke may impair the Eustachian tube function, making children more prone to ear infections. 

Exposure to smoke among children in the USA is still very high.  The authors recommend that in future research, biomarkers should be used to validate just how much smoke children are exposed to (e.g., nicotine levels in plasma, urine, saliva, etc.). 

(Kum-Nji P, et al. Pediatrics 2006; 117(5):1745-1754.)    – H.T.