What AQI Do You Need an N95? AQI Levels and Mask Guide

Quick answer: 

There is no single Air Quality Index (AQI) number that automatically means everyone should wear an N95 mask. Your risk depends on the pollutant, how long you are exposed, your activity, and your health.

When air pollution contains fine particles such as PM2.5, a properly fitted, NIOSH-approved N95 respirator can help reduce the particles you breathe in. However, it does not protect against gases such as ozone or carbon monoxide.

As AQI levels rise, reducing outdoor exposure becomes increasingly important. Check local health advisories, limit strenuous activity when recommended, and consider a well-fitting N95 when exposure to particle pollution cannot be avoided.

What the Air Quality Index (AQI) Means

The Air Quality Index, or AQI, is a color-coded scale used in the United States to communicate how polluted the air is and what that pollution may mean for your health.

The US Environmental Protection Agency (EPA) reports AQI values for five major air pollutants:

• Fine and coarse particle pollution, including PM2.5 and PM10
• Ground-level ozone
• Carbon monoxide
• Sulfur dioxide
• Nitrogen dioxide

The AQI scale runs from 0 to 500. Higher readings indicate greater health concerns.

You can check current readings, forecasts, and the main pollutant affecting your area through AirNow.gov.

Knowing which pollutant is driving the AQI matters because different pollutants require different precautions. An N95 can filter airborne particles, but it does not filter harmful gases.

AQI Mask Chart: Which Level Needs an N95?

Use this chart as a quick reference. The colors match the EPA scale, and the advice depends on air quality and how long you’ll be outside.

*Sensitive groups include children, adults over 65, pregnant people, and people with asthma, COPD, heart disease, or other lung and heart conditions.

How Long You’ll Be Outside Matters

A short walk from the car into a store doesn’t need a mask, even on a bad day. Time and effort change the answer. This table combines the AQI with what you’re doing:

This is general guidance, not medical advice. If you have a heart or lung condition, follow your doctor’s plan first.

AQI Levels Explained

• Good (0 to 50, green): Air quality is satisfactory, with little or no risk.
• Moderate (51 to 100, yellow): Air quality is acceptable. Unusually sensitive people may notice a cough or itchy eyes after a long time outdoors.
• Unhealthy for Sensitive Groups (101 to 150, orange): Sensitive groups may feel effects. Most other people are usually fine.
• Unhealthy (151 to 200, red): Everyone may start to feel effects. Sensitive groups may feel more serious ones.
• Very Unhealthy (201 to 300, purple): A health alert. Everyone may feel more serious effects.
• Hazardous (301 to 500, maroon): Emergency conditions. The whole population is more likely to be affected.

Quick checks for common readings:

• An AQI of 73 is Moderate (yellow). Most people can carry on as normal.
• An AQI of 113 or 140 is Unhealthy for Sensitive Groups (orange).
• An AQI of 152 is Unhealthy (red) for everyone.
• An AQI of 500 is the top of the scale, in the Hazardous category.

What does a yellow AQI mean? 

It means Moderate, which covers 51 to 100. The air is acceptable for most people. Only unusually sensitive people may notice symptoms after a long time outdoors.

What AQI level is unhealthy? 

An AQI of 101 to 150 is unhealthy for sensitive groups. An AQI of 151 and up is unhealthy for everyone.

Which Mask Works Best for Bad Air?

Masks don’t all handle smoke and fine particles the same way. Here’s how the common options compare.

The seal matters as much as the filter. A good filter can’t work if unfiltered air leaks in around the edges.

KN95 masks follow a different standard (GB2626), and quality varies by brand. If you choose one, buy from a seller who can show you the markings and the manufacturer’s details.

How to Get a Good Seal With an N95

An N95 filters at least 95% of airborne test particles, but only when air passes through the filter, not around it.

1. Check that it’s NIOSH-approved: The mask should carry the NIOSH marking and a TC approval number. Match both on the NIOSH Certified Equipment List.
2. Set the straps and nose clip: Put the top strap high on the back of your head and the bottom strap below your ears. Press the metal nose clip to the shape of your nose.
3. Do a seal check every time: Cover the mask with both hands and breathe out gently. If you feel air leaking at the edges, adjust the straps and nose clip, then test again.
4. Keep the sealing area clear: Stubble or a beard that crosses the sealing edge can stop a good seal. If your glasses fog, air is probably leaking at the nose.
5. Don’t expect it to stop gases: An N95 doesn’t filter ozone, carbon monoxide, or nitrogen dioxide. On high-ozone days, limit outdoor time instead.

How long can you wear one? 

There’s no fixed hour limit for smoke or dust. Take it off in clean air if you feel dizzy or short of breath. Replace it when it’s dirty, damaged, hard to breathe through, or no longer seals well. In heavy smoke, filters can clog sooner, so keep a few spares.

What about exhalation valves? 

A valved N95 makes breathing out easier while still protecting you. The valve lets your breath out unfiltered, though, so a valve-free model is the better choice when you need to protect others around you.

Browse our Benehal N95 masks and choose a pack size that matches how often you’ll need them. For a deeper look at masks and outdoor air, read our guide on N95 masks for air pollution and when you need one.

How to Read an AQI Chart

An AQI map shows the index for different places and times, using the six colors above.

1. Find your location. Use the ZIP code search on AirNow.gov, or the map dot nearest you.
2. Read the number and color. This is the latest reading.
3. Check the main pollutant. If it’s PM2.5, an N95 is the right kind of protection. If it’s ozone, plan around the heat of the day and limit outdoor time.
4. Look at the trend. A rising line means conditions are getting worse. Plan outdoor time for the cleanest hours.
5. Check the forecast. Wind and weather can change AQI quickly, so a forecast helps you plan ahead.

AirNow.gov has official real-time maps, forecasts, and historical data for U.S. ZIP codes.

Protect Your Indoor Air Too

Most people spend most of their day indoors, so what you do at home often matters more than what you wear outside.

• Close windows and doors on bad-air days.
• If your AC or heating system has a recirculate setting, use it.
• Run a HEPA air purifier in the room you use most.
• Avoid indoor smoke sources such as cigarettes, candles, and incense.
• Use a range hood or open a window when you cook.
• Plan exercise, play, and yard work for the cleanest hours of the day.

Some tasks stir up dust even indoors. Sanding, sweeping an attic, or cleaning a dusty garage are good times to wear an N95. For dirty surfaces and debris, pair it with disposable nitrile gloves.

Who Needs Extra Care?

Some people should start protecting themselves at a lower AQI:

• Children and teens
• Adults over 65
• Pregnant people
• People with asthma, COPD, heart disease, or other lung and heart conditions

Not every N95 is designed or approved for children, and a good seal is hard to get on a small face. Parents should follow public health guidance and ask a pediatrician about the best plan for their child. On bad-air days, keeping kids indoors is often the simplest step.

Pregnant people and anyone with a heart or lung condition should talk to a doctor before wearing an N95 for long periods. Remove the mask and seek medical help if you feel dizzy, short of breath, or unwell.

Where to Check Your Local AQI

• AirNow.gov is the EPA’s official site, with readings, forecasts, and maps by ZIP code.
• The AirNow app from the EPA gives the same official data on your phone.
• Your state or county air agency may publish more detailed local readings and wildfire alerts.

Commercial sensor apps can be handy for a quick look at your street, but check them against official readings before you plan around them.

Outside the United States

This guide uses the U.S. AQI scale. Many other countries use their own indexes with different cutoffs and category names. If you’re outside the U.S., check your national air quality agency and use its scale.

Frequently Asked Questions

Q: What does the air quality index (AQI) mean?

Ans: The AQI is a scale from 0 to 500 that shows how polluted the air is. Lower numbers mean cleaner air. Each range has a category, a color, and a health message.

Q: What AQI level is unhealthy?

Ans: An AQI of 101 to 150 is unhealthy for sensitive groups. An AQI of 151 and up is unhealthy for everyone.

Q: When should I wear a mask for air quality?

Ans: For most healthy adults, a mask isn’t needed at 100 or below. From 101 to 150, it’s optional and most useful for long or hard outdoor work or for sensitive people. From 151 up, wear a fitted N95 if you have to be outside. At 201 and up, stay indoors when you can.

Q: Is an AQI of 73 bad?

Ans: No. It falls in the Moderate range, which is acceptable for most people. Sensitive people may want to take it easier during hard exercise.

Q: Is a yellow AQI bad?

Ans: A yellow AQI means Moderate. The air is acceptable for most people. Sensitive people may notice symptoms after a long time outdoors.

Q: Do N95 masks work for AQI and smoke?

Ans: A properly fitted, NIOSH-approved N95 filters at least 95% of airborne test particles, including the fine particles in smoke. It doesn’t filter gases, so limit time outdoors on high-ozone days.

Q: Is a surgical mask good for bad air?

Ans: Not for smoke. It’s made mainly to block droplets and splashes, and it doesn’t seal to your face, so particles can get in around the edges.

Q: Is PM2.5 the same as AQI?

Ans: No. PM2.5 is one of the pollutants the AQI tracks. The AQI is the overall number that combines the pollutants and gives you the health category.

Q: Can I wear an N95 with a beard?

Ans: Facial hair along the sealing edge can stop the mask from sealing, which lowers protection. If you can’t shave, limit outdoor time on bad-air days instead of relying on the mask.

Q: How long can I wear an N95 in smoke?

Ans: There’s no fixed time. Replace it when it’s dirty, damaged, hard to breathe through, or no longer seals well.

Stay Ready for Smoke Season

Check the AQI each morning, keep a few NIOSH-approved N95S at home, and store spares sealed and away from heat and moisture. If your household, clinic, or team needs a supply, browse our Benehal N95 masks or book a meeting, and we’ll help you choose quantities.

Related reading:

• N95 masks for air pollution and when you need one
• Hospital mask mandates in 2026
• PPE buying guide for flu season

Sources

• U.S. Environmental Protection Agency, AirNow: https://www.airnow.gov
• U.S. EPA, Fact Sheet on the 2024 PM2.5 standard and AQI update: https://www.epa.gov/system/files/documents/2024-02/pm-naaqs-air-quality-index-fact-sheet.pdf
• CDC, National Institute for Occupational Safety and Health (NIOSH), respirator approvals and the Certified Equipment List: https://www.cdc.gov/niosh/
• Occupational Safety and Health Administration, respiratory protection: https://www.osha.gov/respiratory-protection

This article is general information and not medical advice. If you have a health condition, talk to your doctor about your risk.