Where to check smog and air quality in real time

The fastest way to see smog and air quality near you is to visit AirNow.gov, which shows current conditions for your exact location. Type your zip code or city name, and you get a color-coded number called the Air Quality Index (AQI). Green means good air; yellow means moderate; orange, red, and purple mean increasingly unhealthy conditions. The map updates every hour.

If you are on your phone, the AirNow app (free, available on iPhone and Android) gives you the same real-time data without typing. You can also search "air quality near me" in Google Maps, which pulls AirNow data directly into the map view. Both show you which pollutants are highest right now — usually ozone or particulate matter — and which neighborhoods have the worst readings.

State environmental agencies also post their own air quality pages. If you live in California, check SCAQMD.org (South Coast) or your regional air district's website. Texas residents can check the TCEQ website. These state sites sometimes update faster than AirNow and show more detail about which industrial or traffic sources are driving pollution in your area.

Key Takeaways

  • AirNow.gov and the AirNow app show current air quality for your location updated hourly, with a color-coded number that tells you whether air is safe to breathe.
  • The Air Quality Index (AQI) ranges from green (good) to purple (hazardous), and each level comes with health guidance for different groups.
  • Your state environmental agency website often has more detailed local pollution data and forecasts than the federal AirNow site.
  • When AQI is orange or higher, people with asthma, heart disease, or respiratory conditions should limit outdoor activity.

Understanding the Air Quality Index numbers and colors

The AQI is a single number between 0 and 500 that tells you how polluted the air is. Each range has a color and a meaning. 0–50 (green) means good air — safe for anyone to be outside. 51–100 (yellow) means moderate air — most people are fine, but people with asthma or heart problems may notice symptoms. 101–150 (orange) means unhealthy for sensitive groups — children, older adults, and people with lung or heart disease should avoid outdoor exercise. 151–200 (red) means unhealthy for everyone — limit outdoor time. 201–300 (purple) means very unhealthy — stay indoors. 301+ (maroon) means hazardous — everyone should avoid going outside.

The AQI is based on whichever pollutant is worst that day. In summer, that is usually ozone (smog). In winter or near fires, it is usually particulate matter — tiny dust and soot particles you can sometimes see as haze. AirNow tells you which pollutant is driving the number, so you know whether to worry about ground-level ozone or smoke.

What to do when smog is heavy

When the AQI is orange or higher, limit time outside, especially if you have asthma, heart disease, or are over 65. If you must go out, wear an N95 or P100 mask — cloth masks do not filter smog. Keep car windows closed and use the recirculate setting on your air conditioning. Stay away from heavy traffic and highways, where pollution is worst.

Indoors, close windows and doors, and run an air purifier with a HEPA filter if you have one. Do not exercise outside when the AQI is red or higher. If you have a chronic lung or heart condition, call your doctor for guidance — some people need to adjust medications or avoid outdoor activity for longer periods than the general public.

Check the forecast before planning outdoor activities. AirNow and most state air quality sites show a one- to two-day forecast so you can move exercise or errands to a cleaner day. Smog is usually worst in the afternoon and early evening, so morning is often the best time to be outside.

Regional differences in air quality data

Some states and cities have their own air quality monitoring networks that are more detailed than the national AirNow system. California has the most extensive network — every major city has multiple monitors, and you can see block-by-block variation. Texas posts data through TCEQ. Arizona uses the Arizona Department of Environmental Quality site. If you live in a major metro area, your city or county health department may also have an air quality page.

Rural areas often have fewer monitors, so the nearest reading may be 20 or 30 miles away. If you live in a rural area and the nearest monitor shows orange, your actual air may be better or worse depending on wind direction and local sources. Wildfire smoke, for example, can make air unhealthy in rural areas while nearby cities stay green.

How to set up alerts for bad air days

The AirNow app lets you set alerts so you get a notification when the AQI reaches a level you choose — for example, when it hits orange. You can set different alert levels for different locations if you work in one city and live in another. Most state air quality websites also offer email alerts.

If you have a smartphone, you can also enable weather alerts through your phone's built-in weather app, though these are less detailed than AirNow alerts. Some cities send SMS or email alerts through their health departments — check your city or county website to see if you can sign up.

Why smog happens and when it is worst

Smog forms when sunlight hits pollution from cars, factories, and power plants. That is why it is usually worst in summer, especially in the afternoon when the sun is strongest. Cities surrounded by mountains — like Los Angeles, Phoenix, and Denver — trap smog in a bowl, so pollution builds up instead of blowing away. Coastal cities usually have better air because ocean breezes push pollution inland.

Wildfire smoke is a separate problem that can make air unhealthy even in places with little local pollution. Smoke travels hundreds of miles, so a fire in another state can affect your air quality. During fire season (usually summer and fall in the West), check whether the AQI is driven by local ozone or by smoke from distant fires — the health guidance is the same, but the forecast is different.

Frequently Asked Questions

What does an AQI of 150 mean for my health?

An AQI of 150 (red) means the air is unhealthy for everyone. People with asthma, heart disease, or lung disease should avoid outdoor activity. Healthy adults should limit outdoor time and avoid strenuous exercise. If you must go outside, wear an N95 mask and try to stay away from traffic.

Can I trust the AirNow reading if I live far from a monitor?

AirNow uses data from the nearest monitor, which may be 10 to 50 miles away depending on where you live. If you are in a rural area, the reading is an estimate. Local wind, terrain, and nearby pollution sources can make your actual air better or worse. If the reading seems wrong, check your state environmental agency's website — they may have a closer monitor.

Is an N95 mask enough to protect me from smog?

An N95 or P100 mask filters most particulate matter (dust and smoke) but not ozone gas. If the smog is driven by ozone, a mask helps less. The best protection is to stay indoors when the AQI is high. If you must go out, a mask is better than nothing, but limiting time outside is more effective.

How far in advance can I see the air quality forecast?

AirNow shows a one- to two-day forecast. Your state environmental agency may show longer forecasts — some show three to five days ahead. Forecasts are less accurate the further out they go, so a two-day forecast is usually reliable, but a five-day forecast is a rough estimate.

Why does my area show good air on AirNow but I can see haze?

Haze does not always mean unhealthy air by the AQI standard. You might be seeing dust, humidity, or pollution that is not thick enough to trigger an orange or red reading. Check the AQI number itself — if it is still green or yellow, the air meets the standard for safe outdoor activity, even if visibility is poor. If you have respiratory problems and the haze bothers you, stay indoors anyway.