How to check air quality and smog in your area right now

The fastest way to see smog and air quality near you is to visit AirNow.gov, which shows real-time pollution levels for your zip code. Type in your location and you'll see the Air Quality Index (AQI) — a number from 0 to 500 that tells you how clean or polluted the air is. Green means good air; yellow means moderate; orange, red, and purple mean increasingly unhealthy conditions. The map updates every hour.

You can also check your phone's built-in weather app — most include an AQI number alongside temperature and forecast. If you want hourly updates sent to your phone, read the official AirNow app or use third-party apps like BreezoMeter or IQAir, which show pollution breakdowns by pollutant type (ozone, particulate matter, nitrogen dioxide, and others).

Your state's environmental agency also tracks smog. Search "[your state] air quality" to find their monitoring network, which often shows data from specific monitoring stations near you and historical trends over days or weeks.

Key Takeaways

  • AirNow.gov shows real-time air quality for your zip code and updates every hour with a color-coded health rating.
  • The Air Quality Index (AQI) is a single number from 0 to 500 that tells you whether air is good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy, or hazardous.
  • Your phone's weather app usually displays the AQI, and dedicated apps like AirNow, BreezoMeter, and IQAir send alerts when pollution spikes.
  • State environmental agencies maintain their own monitoring networks and historical data, useful if you want to track patterns over weeks or months.
  • Smog levels change by neighborhood and hour, so checking before outdoor activities — especially for children, older adults, and people with asthma — helps you plan safely.

What the Air Quality Index numbers mean for your health

The AQI scale runs from 0 to 500, and each range has a color and a health message. 0–50 (green, "Good") means air quality is satisfactory and outdoor activity is safe for everyone. 51–100 (yellow, "Moderate") means air quality is acceptable, but sensitive groups — children, older adults, and people with heart or lung disease — may experience minor symptoms during prolonged outdoor activity.

101–150 (orange, "Unhealthy for Sensitive Groups") means members of sensitive groups should limit prolonged outdoor exertion; the general public is less affected. 151–200 (red, "Unhealthy") means everyone may begin to experience health effects, and sensitive groups will have more serious symptoms. 201–300 (purple, "Very Unhealthy") means the general public is now at risk, and sensitive groups face serious health effects. 301+ (maroon, "Hazardous") means everyone should avoid outdoor activity.

These ranges explore to smog (ground-level ozone) and particulate matter (PM2.5 and PM10), the two pollutants most commonly reported. Other pollutants like nitrogen dioxide and sulfur dioxide are tracked separately and may have different thresholds.

Why smog levels change hour to hour and season to season

Smog is not a fixed problem — it builds and clears based on weather, traffic, and industrial activity. Ground-level ozone, the main component of smog, forms when sunlight reacts with nitrogen oxides and volatile organic compounds from car exhaust and factories. On hot, sunny days with little wind, ozone accumulates and smog gets worse. On cool, cloudy, or windy days, pollution disperses and air clears.

Time of day matters too. Ozone typically peaks in the afternoon and early evening after hours of sun exposure, so morning air is often cleaner than evening air. Rush hour traffic (roughly 7–9 a.m. and 4–6 p.m.) also pushes pollution levels up in urban areas.

Smog is worst in summer and early fall when heat and sunlight are strongest. Winter often brings cleaner air, though cold, stagnant conditions can trap pollution near the ground in some regions. Wildfires, dust storms, and industrial events can spike pollution suddenly regardless of season.

What to do when smog is unhealthy in your area

When the AQI reaches orange or higher, limit time outdoors, especially for children, older adults, and people with asthma, heart disease, or other respiratory conditions. If you must go outside, wear an N95 or P100 mask, which filters out fine particles; cloth masks and surgical masks do not block smog effectively.

Keep windows and doors closed during high-pollution days, and run your air conditioner on recirculate mode (not fresh air intake) to filter indoor air. If you don't have air conditioning, stay in air-conditioned public spaces like libraries, malls, or community centers. Avoid strenuous outdoor exercise — even a short run can draw polluted air deep into your lungs.

If you have asthma or another respiratory condition, keep your rescue inhaler with you and check the AQI before leaving home. Some people find that staying indoors on high-pollution days prevents symptoms entirely. If you experience chest pain, shortness of breath, or severe coughing during high-smog days, seek medical attention.

How monitoring stations work and why coverage varies by location

Air quality data comes from monitoring stations operated by state and local environmental agencies, often in partnership with the EPA. These stations measure pollutants continuously and report data to AirNow.gov. Urban areas typically have more stations than rural areas, so you may see precise neighborhood-level data in a city but only regional data in a small town.

Stations are placed strategically — near highways to catch traffic pollution, in residential areas to measure what people breathe, and in industrial zones to track factory emissions. The location of the nearest station to your home affects how accurately the reported AQI reflects your actual air. If you live in a valley or near a major highway, your air may be worse than the nearest station reports; if you live upwind of pollution sources, it may be better.

Some apps use satellite data and modeling to fill gaps where ground stations are sparse, which can be useful but is less precise than direct measurement. If you live in a rural area or small town with no nearby station, checking a regional or state-level report gives you a general sense, but your actual conditions may differ.

State and local resources for smog information and alerts

Every state has an environmental or air quality agency that tracks smog and publishes data online. Search "[your state] air quality" or "[your state] environmental protection agency" to find their website. Many states offer email or text alerts when the AQI reaches unhealthy levels — sign up on their website to get notified before pollution spikes.

Local health departments and county air quality management districts also publish smog forecasts and health advisories. In California, for example, the South Coast Air Quality Management District (SCAQMD) issues forecasts days in advance. In the Northeast, the New York State Department of Environmental Conservation does the same. These forecasts help you plan outdoor activities ahead of time.

If you live near a major highway, airport, or industrial area, your local government may have a community air monitoring program. Some neighborhoods have installed their own low-cost sensors to track hyperlocal pollution, and data from these networks is sometimes shared publicly.

Frequently Asked Questions

Is the AQI the same everywhere, or does it change by neighborhood?

The AQI changes by location and hour. Pollution is worst near highways, industrial areas, and power plants, and cleanest in rural areas and upwind of cities. A single city may have multiple monitoring stations showing different readings. Check the map on AirNow.gov to see stations near your specific address rather than relying on a citywide average.

Can I trust air quality data from my phone's weather app?

Yes, most major weather apps pull data from AirNow.gov or official government sources, so the numbers are reliable. However, the data is only as precise as the nearest monitoring station. If your phone shows data for your city but the nearest station is 20 miles away, your actual air may differ. Cross-check with AirNow.gov to see where the station is located.

What does it mean if the AQI is different on different apps?

Different apps may report different numbers because they use different data sources, update at different times, or calculate averages differently. AirNow.gov is the official government source and updates hourly, so use that as your reference. If another app shows a very different number, check when it last updated and which monitoring station it's using.

Is smog worse in cities or rural areas?

Smog is typically worse in cities and downwind of cities because of traffic and industrial emissions. However, rural areas near highways, farms, or industrial facilities can also have poor air quality. Wildfire smoke can affect air quality across hundreds of miles, making rural areas temporarily worse than cities. Check your specific location rather than assuming based on whether you live in town or country.

Do I need to wear a mask every day if I live in a high-smog area?

No. Wear a mask only when the AQI reaches orange or higher, or if you have asthma or another respiratory condition and the AQI is yellow. On green and yellow days, most people can breathe safely outdoors. If you have a chronic lung condition, talk to your doctor about when masking is necessary for you personally.