Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Locations of the air quality monitors and meteorological stations used in this study. Outer line represents the boundary of Vienna and inner lines represent the city’s districts. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article)
