Background:
Secondhand smoke (SHS) exposure has been linked to numerous health conditions.The harmful health effects of SHS exposure have resulted in excess economic costs. National-level studies on the economic impact of SHS exposure are limited in the U.S. To provide the latest information on the national-level costs of SHS exposure in U.S., this study estimated healthcare costs attributable to SHS exposure at home among nonsmoking adults (18+) in the U.S. in 2000, 2005, and 2010.

Methods:
We analyzed nonsmoking adults (N=67,735) using data from the 2000, 2005, and 2010 (the latest avaiable data on SHS exposure) U.S. National Health Interview Surveys. We examined hospital nights, home health care visits, doctor visits, and emergency room (ER) visits. For each, we analyzed the association of SHS exposure at home with healthcare utilization with a Zero-Inflated Poisson regression model controlling for socio-demographic and other risk characteristics (including age, gender, race and ethnicity, education, poverty status, and number of months without health insurance). Excess healthcare utilization attributable to SHS exposure was determined and multiplied by unit costs derived from the 2014 Medical Expenditures Panel Survey to determine SHS-attributable healthcare costs.

Results:
SHS exposure was positively associated with hospital nights and ER visits, but was not statistically associated with home health care visits and doctor visits. The total annual SHS-attributable healthcare costs in 2000, 2005 and 2010 were $4.6 billion (including $3.8 billion for hospital nights and $0.8 billion for ER), $2.1 billion (including $1.8 billion for hospital nights and $0.3 billion for ER), and $1.9 billion (including $1.6 billion for hospital nights and $0.4 billion for ER), respectively.

Conclusions:
SHS-attributable costs remain high, but have fallen over time. Tobacco control efforts are needed to further reduce SHS exposure and associated healthcare costs.