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

. 2020 Jul 6;743:140758. doi: 10.1016/j.scitotenv.2020.140758

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

© 2020 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. 1 — Time series of PM_2.5, SO₂, NO_x (NO and NO₂), CO, and O₃ from Jan. 8 to Feb. 9 in 2020 at the Xinjiangwan air quality station in Shanghai. The three phases are presented with different background colors. Four typical PM_2.5 pollution episodes are presented with corresponding double-headed arrows.