The most common way that bronchitis is spread through contact with the virus in the same manner that the cold and flu virus is spread.
Virus-Direct Contact and Indirect Contact
Bronchitis is spread through both direct and indirect contact. The virus is carried through the contaminated respiratory droplets of an infected person discharged through the nose or mouth. These contaminated droplets can directly infect another person through direct air inhalation. The infection can also spread indirectly through inanimate objects. For example, if an infected person coughs on his hands then uses the telephone, the virus can live on the telephone handset for hours. The next person to use the telephone is then at risk for contracting the virus. (“Respiratory -RSV-Fact Sheet.”, dhs.wisconsin.gov)
Less commonly, bronchitis can be contracted by being exposed to respiratory irritants such as pollution, dust, smoke, vapors, and fumes. (“Acute Bronchitis:Medline Plus”, nlm.nih.gov) Bronchitis caused by irritants are not contagious and do not spread to others in the same manner that viral bronchitis is spread. (Cunha DO FACOEP, John P, emedicinenet.com)
 “Acute Bronchitis: MedlinePlus.” National Library of Medicine – National Institutes of Health. N.p., n.d. Web. 12 Mar. 2012. http://www.nlm.nih.gov/medlineplus/acutebronchitis.html
 “Respiratory -RSV-Fact Sheet.” Wisconsin Department of Health Services. N.p., n.d. Web. 12 Mar. 2012. http://www.dhs.wisconsin.gov/communicable/factsheets/RespiratoryRSV.htm
 Cunha DO FACOEP, John P. “Is Bronchitis Contagious.” eMedicinenet.com. N.p., n.d. Web. 12 March. 2012. http://www.emedicinehealth.com/bronchitis/page2_em.htm