. 2020 Mar 12;17(6):1828. doi: 10.3390/ijerph17061828
© 2020 by the authors.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Figure 1.
A flow chart for study population selection.