Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

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.

View full-text article in PMC

. 2021 Jan 31;10:100105. doi: 10.1016/j.aeaoa.2021.100105

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2021 The Authors

Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

PMC Copyright notice

Fig. 4 — Central Phoenix CO and NO₂ concentrations (A & B) and CO and NO₂ concentrations adjusted for boundary layer height (C & D) for 2020, 2019, and 2018. The gray shaded area represents the pre-SAH period and the red shaded area represents the SAH period. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)