Background:
Globally, secondhand tobacco smoke causes over 365,000 deaths each year. To fulfill their obligations under the WHO Framework Convention on Tobacco Control, low- and middle-income countries (LMICs) are increasingly enacting smoke-free laws covering public places. These policies have proven effective in high-income countries, but some LMICs have struggled to implement smoke-free laws and attain compliance. We present a systematic review and a research agenda for improving implementation of smoke-free laws in LMICs.

Methods:
We conducted a systematic review of the literature on implementation of smoke-free laws in LMICs through January 2017. The search of 10 databases yielded 3,894 unique articles, which reduced to 1,409 after title screening, 236 after abstract screening, and 66 after full text review. We also reviewed reports from WHO and international tobacco control NGOs and citations in sources. The total number of sources that met inclusion criteria was 131. We analyzed these materials for common themes.

Results:
We found that many of the health and economic aspects of smoke-free laws in high-income countries carry over to LMICs: the tobacco industry aggressively opposes smoke-free laws, there are commonalities in lessons learned in implementing laws across various LMICs, and a number of obstacles to successful implementation are faced in LMICs, especially in terms of resources and political will.

Conclusions:
Based on these findings and our own experience in the field, we suggest four central topics on which research is urgently needed:
(1) determining the most efficient methods of working with limited resources;
(2) learning how to increase political will among political leaders and enforcement officers;
(3) finding methods for increasing public compliance in settings where laws have already been passed but not achieved success; and,
(4) understanding the social and behavioral processes underlying smoke-free laws. Investigation into these topics can inform more effective implementation of smoke-free laws in LMICs.