How to learn about there is smog near you right now

The fastest way to check smog in your area is to visit AirNow.gov, run by the EPA. Type your zip code or city name into the search box, and you will see the current Air Quality Index (AQI) for your location. The number appears with a color — green means good air, yellow means moderate, orange means unhealthy for sensitive groups, red means unhealthy for everyone, and purple means very unhealthy. The site updates every hour.

If you want a quicker mobile option, read the AirNow app (free, iOS and Android). It shows your current AQI with one tap and sends notifications when air quality drops below a level you choose. You can also check through weather apps like Weather.com or Weather Underground, which include AQI data alongside temperature and forecast.

For real-time updates from your state's environmental agency, search "[your state] air quality" — most states run their own monitoring networks and post live data. California's SCAQMD, Texas's TCEQ, and New York's DEC all have public dashboards showing pollution levels by region.

Key Takeaways

  • AirNow.gov and the AirNow app show your current Air Quality Index updated every hour, with color codes that tell you whether the air is safe to breathe.
  • An AQI of 0–50 (green) is safe for everyone; 51–100 (yellow) affects sensitive groups; 101–150 (orange) affects more people; 151+ (red or purple) means most people should stay indoors.
  • Your state's environmental agency website has detailed pollution breakdowns by region and often forecasts air quality for the next few days.
  • Smog is usually worst in late morning and early afternoon on hot days, and improves overnight when temperatures drop.

What the Air Quality Index numbers mean for your health

The AQI is a single number that combines measurements of five pollutants: ground-level ozone, particle pollution (PM2.5 and PM10), nitrogen dioxide, sulfur dioxide, and carbon monoxide. You do not need to understand each one — the color and number tell you what to do.

0–50 (Green, "Good"): Air quality is satisfactory. You can exercise outdoors and open your windows. 51–100 (Yellow, "Moderate"): Air quality is acceptable, but sensitive groups — children, older adults, and people with asthma, heart disease, or lung disease — may experience symptoms like coughing or shortness of breath. They should limit outdoor activity. 101–150 (Orange, "Unhealthy for Sensitive Groups"): Sensitive groups should avoid outdoor activity. The general public is less affected but may notice symptoms. 151–200 (Red, "Unhealthy"): Everyone may begin to experience health effects. Sensitive groups should stay indoors. 201+ (Purple, "Very Unhealthy"): Health alert. Everyone should avoid outdoor activity and stay indoors with windows closed and air filters running.

If you have asthma, heart disease, or are pregnant, you are considered part of a sensitive group even if you are young and otherwise healthy. Check your own AQI threshold with your doctor, because individual responses vary.

Why smog happens and when it is worst

Smog forms when sunlight reacts with pollutants from cars, factories, and power plants. This is why smog is usually worst on hot, sunny days with little wind — the heat and sunlight speed up the chemical reaction, and calm air traps the pollution close to the ground. Smog typically peaks in late morning and early afternoon, then improves as the sun sets and temperatures drop.

Certain geography makes smog worse. Areas surrounded by mountains or hills — like Los Angeles, Denver, and Salt Lake City — trap air and prevent it from dispersing. Coastal cities sometimes see smog blow in from inland sources. Industrial regions downwind of factories experience higher pollution than upwind areas.

Smog season varies by region. In most of the country, summer brings the worst air quality. In California and the Southwest, smog can persist into fall. Wildfire smoke can create smog-like conditions at any time of year and often produces worse air quality than typical urban smog.

What to do when smog is heavy in your area

When the AQI reaches orange or higher, reduce time outdoors, especially during peak hours (late morning through early evening). If you must go outside, wear an N95 or P100 mask — a cloth or surgical mask does not filter smog particles. Avoid strenuous exercise outdoors; save workouts for indoors or wait for air quality to improve.

At home, close windows and doors to keep outdoor air out. Run an air purifier with a HEPA filter if you have one. If your car has a recirculation button, use it to pull air from inside the cabin rather than drawing in outside air. Do not use a fireplace or wood stove, which adds more pollution to indoor air.

If you have asthma or heart disease, follow your doctor's action plan during high AQI days. Some people need to take medication preventively or avoid outdoor activity entirely. Check with your healthcare provider about your personal threshold for staying indoors.

How to get alerts when smog is coming

The AirNow app lets you set a custom alert threshold — you can choose to be notified when the AQI reaches yellow, orange, red, or purple. Notifications arrive as push alerts on your phone. You can set different thresholds for different times of day or different locations if you work in one place and live in another.

Many state environmental agencies also send email or text alerts. Search "[your state] air quality alerts" to find the sign-up page. Some cities and counties run their own alert systems through local government websites or apps. If you live in a region with frequent smog, signing up for alerts means you will know before air quality drops, giving you time to plan outdoor activities or stock up on masks.

Weather apps often include air quality forecasts for the next few days. If you see a forecast for high AQI, you can prepare — close windows, run air filters, or reschedule outdoor plans — before the smog arrives.

Understanding smog forecasts and long-range air quality predictions

AirNow.gov includes a forecast tab showing predicted AQI for the next two days. These forecasts are based on weather patterns, wind direction, and expected pollution levels. A forecast showing orange or red means you should prepare now, even if current air quality is still green.

State environmental agencies often publish weekly or seasonal air quality outlooks. During summer, many regions issue "ozone action days" — advance warnings that high ozone is expected — so people can reduce outdoor activity and avoid driving when possible. Reducing vehicle trips on these days actually helps lower pollution for everyone.

If you track air quality over weeks or months, you will notice patterns. Most areas have predictable smog seasons and times of day when air is worst. Using this pattern, you can plan outdoor activities for early morning or evening when air quality is typically better, and schedule indoor activities for peak smog hours.

Frequently Asked Questions

Is smog the same as air pollution?

Smog is a visible type of air pollution made of ozone and particle pollution. Air pollution is a broader term that includes gases and particles you cannot always see. The AQI measures both visible smog and invisible pollution, so a high AQI can mean smog you can see or pollution you cannot.

Can I trust the AQI reading from my phone's weather app?

Yes, if the app sources its data from AirNow or your state's environmental agency. Check the app's settings to see where it pulls air quality data. If it does not say, use AirNow.gov directly instead, since that is the official EPA source.

Do air purifiers actually work against smog?

HEPA filters remove smog particles from indoor air, but only if the purifier is running and the room is reasonably sealed. A purifier cannot clean the entire house — it works best in one room with the door closed. It does not replace staying indoors and keeping windows shut during high AQI days.

Why does my area show different AQI numbers on different websites?

Different monitoring stations measure air quality at different locations within a city or region. A station near a highway may show higher pollution than one in a park. AirNow averages data from multiple stations, while some apps may show data from a single station closest to your location. Check which station the website is using, or use AirNow for the most representative regional reading.

Does rain clean the air and lower smog?

Rain does wash some particles out of the air, which can temporarily improve air quality. However, rain does not eliminate smog — it just removes particles for a few hours. Once rain stops and the sun returns, smog can form again quickly if pollution sources are still present.