Air Quality Guides
In-depth guides to understanding air quality, the pollutants that affect it, the health impacts, and how to protect yourself and your family. Browse by topic below.
Understanding Air Quality
Understanding the AQI
How the Air Quality Index works and what the colors mean.
Read guide →Common Air Pollutants
The major pollutants the AQI tracks, explained.
Read guide →PM2.5 & Particulate Matter
What fine particles are and why they matter for health.
Read guide →Ozone Pollution
How ground-level ozone forms and how to stay safe.
Read guide →Nitrogen Dioxide (NO2)
Sources, health effects, and exposure tips.
Read guide →Carbon Monoxide (CO)
Where CO comes from and the risks it poses.
Read guide →Sources of Air Pollution
Where air pollution comes from across the US.
Read guide →Industrial Pollution
How industry shapes regional air quality.
Read guide →Air Quality Sensors
How AQI is measured and how monitors work.
Read guide →Climate Change & Air Quality
How a changing climate affects the air we breathe.
Read guide →Health & Protection
Health Effects of Air Pollution
How polluted air affects your body short and long term.
Read guide →Air Quality Health Impact
Who is most at risk and what to watch for.
Read guide →Improving Indoor Air Quality
Practical steps to clean the air inside your home.
Read guide →Indoor vs Outdoor Air
How indoor and outdoor air quality relate.
Read guide →Radon in Your Home
Testing, the EPA 4 pCi/L action level, and mitigation cost.
Read guide →Mold & Indoor Humidity
Causes, health effects, DIY cleanup limits, and prevention.
Read guide →Why Is the Air Quality Bad Today?
How to read today's AQI, what is driving it, and what to do.
Read guide →What an Air Quality Alert Means
Alert levels, who they apply to, and how to respond.
Read guide →Indoor Air Quality Testing
What home monitors measure, what they miss, and when to hire a pro.
Read guide →AQI for Outdoor Exercise
Safe AQI thresholds for running, cycling and kids' sports.
Read guide →Best Air Purifiers Guide
How to choose an air purifier that actually works.
Read guide →Wildfire Smoke & Air Quality
Protecting yourself during smoke events.
Read guide →Seasonal Air Quality Patterns
How air quality shifts through the year.
Read guide →Buying Guides: Purifiers, Filters, Masks & Monitors
Air Purifier Size Guide (CADR Explained)
CADR, air changes per hour and the AHAM 2/3 rule, with worked examples.
Read guide →Best Air Purifier for Wildfire Smoke
True HEPA, CADR sizing, carbon for odor, and the box-fan budget option.
Read guide →Best Air Purifier for Allergies & Pets
HEPA, pre-filters, and why ionizers and ozone generators are a bad idea.
Read guide →HEPA vs Activated Carbon
Particles vs gases, and when a purifier needs both.
Read guide →Filter Replacement Guide
How often to change HEPA and carbon filters, and yearly cost.
Read guide →N95 vs KN95 vs P100 for Smoke
Fit, filtration, valves and kids under NIOSH vs GB2626.
Read guide →Do You Need an Indoor Air Quality Monitor?
What consumer monitors measure, what they miss, and who benefits.
Read guide →Radon Monitor vs Test Kit
Short-term kits, long-term detectors and continuous monitors compared.
Read guide →Regional & City Guides
California Air Quality
Smog, wildfires, and the Central Valley.
Read guide →Texas Air Quality
Industry, ozone, and the Gulf Coast.
Read guide →Northeast Air Quality
The I-95 corridor and transported pollution.
Read guide →Midwest Air Quality
Industrial legacy and lake-effect patterns.
Read guide →Los Angeles Air Quality
The LA Basin smog story and health guidance.
Read guide →Houston Air Quality
The Ship Channel and petrochemical emissions.
Read guide →Phoenix Air Quality
Desert dust, heat, and ozone.
Read guide →Denver Air Quality
Mountain inversions and the brown cloud.
Read guide →