Summer Air: How to Protect Yourself When Air Quality Turns Unhealthy

by | Aug 8, 2026

Summer encourages people to spend more time outdoors, but the same weather that brings beach days, cookouts, and outdoor exercise can also create difficult air-quality conditions.

High temperatures and strong sunlight encourage ground-level ozone formation. Wildfires can send fine particulate matter hundreds or thousands of miles from the fire itself. Dry conditions increase dust, while traffic, power generation, grilling, lawn equipment, and other activities add additional pollutants.

The good news is that poor air quality does not always mean staying indoors for an entire summer day. Understanding which pollutant is causing the problem can help people decide when to exercise, when to close the windows, and when additional protection is necessary.

Start With the Air Quality Index

One of the simplest protective measures is checking the Air Quality Index, or AQI, before planning outdoor activities.

The AQI converts measurements of major air pollutants into a color-coded scale. Green represents good air quality, followed by yellow for moderate conditions. Orange means conditions are unhealthy for sensitive groups, while red indicates unhealthy air for the broader population. Purple and maroon represent increasingly serious conditions.

Sensitive groups vary somewhat by pollutant, but often include children, older adults, people with asthma or other lung diseases, and people with certain cardiovascular conditions.

A weather forecast tells you whether it will be hot. An AQI forecast helps tell you whether breathing heavily outdoors during that heat is a good idea.

Ozone Is a Summer Problem You Cannot See

Ground-level ozone is different from the protective ozone layer high above Earth. It forms when nitrogen oxides and volatile organic compounds react in sunlight.

Hot, sunny weather can accelerate those reactions, making ozone a particularly important summer pollutant.

Ozone often reaches its highest concentrations during the afternoon and early evening. If an ozone alert is expected, moving a run, bike ride, yard project, or outdoor practice to the morning may substantially reduce exposure.

Intensity matters too.

Someone sitting outside generally breathes much less air than someone running several miles. During strenuous exercise, breathing becomes deeper and faster, increasing the amount of pollution reaching the lungs. On a moderately poor day, reducing the intensity or duration of exercise may allow someone to remain active while lowering exposure.

Ozone cannot be removed effectively by an ordinary particle filter, and an N95 respirator is not designed to filter ozone gas. Avoiding exposure through timing and activity changes is therefore especially important.

Wildfire Smoke Requires a Different Strategy

Wildfire smoke is largely a particulate problem. Of particular concern is PM2.5, particles small enough to travel deep into the respiratory system.

Unlike ozone, smoke does not follow a reliable afternoon pattern. Wind direction, fire behavior, temperature inversions, and changing weather can cause particle concentrations to rise or fall quickly.

During wildfire events, check current conditions as well as the daily forecast. The AirNow Fire and Smoke Map can show both wildfire locations and nearby particle measurements.

If the air becomes smoky, reduce strenuous outdoor activity and move indoors when possible. People who must spend time outside may benefit from a well-fitting NIOSH-approved N95 or P100 respirator.

These respirators filter particles rather than gases. A loose surgical mask or cloth face covering will generally provide much less protection against wildfire particles because air can leak around the edges.

Make Your Home a Cleaner-Air Space

During prolonged smoke events, keeping indoor air cleaner becomes one of the most effective protective measures.

Close windows and doors when outdoor smoke is heavy. Central air-conditioning systems should generally be placed in recirculation mode when possible so they are not continuously drawing smoky air from outdoors.

EPA recommends considering a MERV 13 or higher HVAC filter during wildfire smoke events if the system can safely accommodate it. Filters must fit correctly and may need to be replaced more frequently during heavy smoke.

Portable air cleaners equipped with HEPA filters provide another option. The unit should be appropriately sized for the room where it will operate. If cleaning the entire home is difficult, one bedroom or living area can be established as a cleaner-air room.

A lower-cost alternative is a properly constructed box-fan air cleaner using a MERV 13 filter. EPA has published designs for these systems and recommends using modern safety-certified box fans.

Do Not Create More Pollution Indoors

Closing the house helps keep outdoor pollution outside, but it also makes indoor pollution more important.

During a smoke event, avoid smoking, burning candles or incense, and using fireplaces. Frying or searing food can create substantial indoor particulate matter, while gas stoves add combustion pollutants.

Vacuuming with equipment that does not effectively capture fine particles may also stir settled dust back into the air.

If possible, prepare food using lower-emission methods during severe smoke periods and use kitchen exhaust that vents outdoors when outdoor conditions permit.

An air cleaner works best when the household is not simultaneously generating more particles.

Cars Can Become Temporary Cleaner-Air Spaces

Driving through wildfire smoke or heavy urban pollution can produce high exposure if windows are open and outside air is continually entering the vehicle.

Close the windows and place the climate-control system in recirculation mode during heavily polluted conditions. Maintaining the vehicle’s cabin air filter can also help reduce particles entering through the ventilation system.

Recirculation should not necessarily be used continuously for extremely long periods, but it can substantially reduce outdoor smoke entering the cabin during a commute or short trip.

Remember That Heat Still Matters

One of the most difficult summer situations occurs when extreme heat and wildfire smoke happen at the same time.

Closing windows may reduce smoke exposure, but an unair-conditioned house can quickly become dangerously hot. Heat illness can present a more immediate threat than air pollution.

People without adequate cooling should not remain in an overheating home simply to avoid outdoor air. Communities may open cooling centers, cleaner-air shelters, libraries, malls, or other air-conditioned public buildings during severe events.

Planning ahead is valuable. Know where you could go before a combination of extreme heat and smoke arrives.

Pay Attention to Your Body

Poor air quality can cause coughing, wheezing, throat irritation, chest discomfort, shortness of breath, headaches, and worsening asthma or other respiratory symptoms.

People who use asthma inhalers or other prescribed respiratory medications should keep them available and follow their existing medical plans. New, severe, or rapidly worsening breathing or cardiovascular symptoms require medical attention.

For most people, protecting themselves during summer pollution is less about completely avoiding the outdoors and more about adjusting intelligently.

Check the AQI. Exercise when conditions are better. Filter indoor air. Keep smoke outside without allowing the home to become dangerously hot. Wear appropriate respiratory protection when particle pollution makes outdoor exposure unavoidable.

Summer air can change quickly. A little information can make the difference between simply noticing that the sky looks hazy and knowing what to do about it.

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