Figure 2.
Questionnaire analysis. (a) The frequency of the devices in different rooms; (b) time period of use in a day; (c) frequency of use in a week; (d) ozone emission rate.
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.