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

. 2025 Aug 1;13:1632713. doi: 10.3389/fpubh.2025.1632713

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

Copyright © 2025 Jing and Xiaofeng.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

PMC Copyright notice

Scatterplot matrix showing correlations between variables A, Year, Non-heating period (NO₂), and Heating period (NO₂). Each panel displays scatterplots with regression lines and ellipses, alongside adjusted R-squared and Pearson's correlation coefficients. Box plots are shown on diagonal panels. — Scatter plot of NO₂ concentration in heating period and non-heating period.