Air pollution basics
What is air pollution?
Air pollution refers to a mixture of harmful particles and gases found in the air we breathe. Air pollution can be found outdoors and indoors.
Where does air pollution come from?
Outdoor air pollution can come from human activities such as motor vehicles (due to burning fossil fuels) and emissions from power plants (like from coal-fired plants). Outdoor air pollution can also come from natural events such as wildfires and dust storms.
Indoor air pollution can come from human activities such as heating and cooking appliances that use wood or coal and smoking tobacco products. Indoor air pollution can also come from natural sources such as mold and pet dander.
Can outdoor air pollutants enter indoors?
Yes, outdoor air pollutants can enter buildings such as through open doors, open windows, and cracks in housing structures.
What are examples of air pollutants?
PM2.5 stands for particulate matter that is less than 2.5 micrometers (or microns) in diameter. PM2.5 is a mixture of solid particles and liquid droplets like dirt, soot, and smoke.
PM10 stands for particulate matter that is less than 10 micrometers in diameter and includes particles like dust, pollen, and mold.
Nitrogen dioxide (NO2) is a gas that is commonly released in traffic.
Carbon monoxide (CO) is a toxic gas that is colorless, odorless, and tasteless.
Ozone (O3) at the ground level is found in smog.
Sulfur dioxide (SO2) is a colorless gas with a pungent odor.
What makes air pollution from wildfires different?
Wildfire smoke includes particles and gaseous pollutants such as PM2.5 in addition to CO, NO2, O3, polycyclic aromatic hydrocarbons, and volatile organic compounds. Wildfire smoke can travel thousands of miles to impact local air quality. Some studies have shown that chemicals released during wildfires may be more toxic and create more harmful mixtures of urban air pollution. Wildfire season in Washington state generally lasts from May to October each year.
How can I learn about the current wildfire smoke forecast in my area?
Visit the Washington Air Quality Map to see a wildfire smoke forecast by selecting SMOKE FORECAST from the View menu. This forecast is based on air pollution monitoring stations.
How does air pollution affect health?
Health effects of air pollution depend on many factors, including which type of air pollutant you are exposed to, how much you are exposed to, how long you are exposed, and your preexisting health conditions.
For example, PM2.5 particles are small and can be inhaled deep into your lungs and enter your blood stream. PM2.5, NO2, O3, and SO2 can irritate and inflame the lining of your nose, throat, and lungs, which can lead to a flare-up of asthma or COPD symptoms as well as worsen the severity of symptoms such as discomfort when you breathe, coughing, wheezing, difficulty breathing, and tightness of your chest. These air pollutants can also reduce the amount of air that your lungs can hold.
Studies have shown that higher concentrations of exposures to air pollutants in the short term (such as daily levels) are associated with more people being hospitalized for health problems related to asthma or COPD. There is also a higher likelihood of developing respiratory illnesses like pneumonia and bronchitis.
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Studies have also shown that air pollution can lead to negative outcomes among pregnant people such as low birth weight and preterm birth.
Long-term exposure to high levels of PM2.5 has been associated with increased risk of developing lung cancer, heart disease, stroke, and death.
Air Quality Index (AQI)
What is the AQI?
The AQI is an indicator that tells you about outdoor air pollution and health. The higher the AQI value, the higher the level of outdoor air pollution and the higher the level of concern for your health.
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What is the difference between the AccuWeather AQI and other AQIs?
The AccuWeather AQI was developed by scientists at Plume Labs by AccuWeather using artificial intelligence (AI) integrating many different data streams such as government-operated monitoring stations, satellite imagery, atmospheric models, and weather datasets. The AccuWeather AQI applies air quality thresholds from the World Health Organization (WHO) to determine if air pollution levels are harmful. In addition, the AccuWeather AQI incorporates information about multiple air pollutants: PM2.5, PM10, NO2, CO, O3, SO2.
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There are other AQIs that are constructed differently and use different air quality thresholds. For example, the Environmental Protection Agency (EPA) AQI uses the EPA air quality thresholds to determine harmful levels of outdoor air pollution and provides a separate AQI for different air pollutants.
How do I use the AccuWeather AQI?
Check the AccuWeather AQI to help plan your day. Use it like a weather forecast. The AQI is updated in real-time, so you can check it anytime before you head outdoors. The overall number on the AccuWeather AQI is determined by the pollutant that is measuring the highest. For example, the AccuWeather AQI value that you see will be whichever air pollutant (PM2.5, PM10, NO2, CO, O3, or SO2) has the current highest value.
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An AQI value of >100 indicates that air quality has exceeded the recommended WHO exposure threshold for one hour. Sensitive groups, such as those with asthma or COPD, or people who are pregnant, may experience immediate symptoms.
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However, you may have symptoms at AQI values <100. Regardless of the AQI, if you are experiencing any symptoms, please consider taking protective measures such as those described on this website.
Where do I check or download the AccuWeather AQI?
To check your real-time AQI for free, visit accuweather.com. Type your location into the search bar. Then click on AIR QUALITY in the top navigation bar.
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To download the AccuWeather app for free onto your phone, go here.
Where can I learn more about the AQI?
Resources can be found here.
N95 masks
What makes an N95 mask effective against air pollution?
N95 masks (also known as N95 respirators) have been shown to reduce the amount of airborne contaminants that you inhale. The "95" refers to the filtration efficiency or how 95% of particles less than 0.3 micrometers in size are filtered out when the mask is correctly used.
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N95 masks have the ability to filter particles like PM2.5 air pollution.
Do N95 masks filter all air pollutants?
N95 masks do not filter gases or vapors.
Are there any precautions when using N95 masks?
Yes, people with certain conditions, like asthma or COPD, may have difficulty breathing while wearing a mask. Some N95 mask models have exhalation valves that can make it easier to breathe and help reduce the build up of heat. Please speak to a health care provider regarding masks that may work best for you.
How do I make sure I am wearing an N95 mask appropriately?
It is important to make sure that you achieve a proper seal when using an N95 mask. Please watch this video for tips on how to put on your N95 mask to make sure it fits the right way.
Where can I purchase N95 masks?
You can usually find N95 masks at hardware stores and pharmacies. For example, here is a selection that you can purchase.
Portable air cleaners
What is a portable air cleaner?
Portable air cleaners, also known as air purifiers, can be used to remove air contaminants from air that is inside of your home.
What type of portable air cleaner should I get?
The right type of portable air cleaner depends on many factors like the size of the room you want to clean. Here are some easy steps to figure out which portable air cleaner to buy that include getting a filter-only device, a HEPA (High Efficiency Particulate Air) filter, determining the right size given the room, and a quiet device. HEPA filters are effective in capturing at least 99.97% of particles as small as 0.3 micrometers in size.
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Detailed guidance from the Environmental Protection Agency can be found here.
How can I create my own portable air cleaner?
If you would like to create your own do-it-yourself (DIY) portable air cleaner, follow the steps in this video. All you need to is a box fan, Minimum Efficiency Reporting Value (MERV) 13 filter, and bungee cord.
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A MERV tells you about a filter's ability to capture larger particles. A MERV 13 filter can capture at least 50% of particles between 0.3 and 10 microns in size.
Where should I put my portable air cleaner?
Consider placing the portable air cleaner in the room(s) where you spend the most time. Make sure the airflow is not obstructed.
Where can I learn more about portable air cleaners?
Resources can be found here.
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Other strategies
Why should I avoid traffic?
Traffic is a major source of outdoor air pollution because of emissions from cars and particles from the wearing of tires. It is recommended to reduce your exposure to traffic-related air pollution by taking alternative routes. For example, if you are able, you can try to avoid high-traffic areas during peak traffic times like during rush hour.
Where should I exercise?
It is recommended to exercise in places that are not close to high-traffic areas. For example, some studies have suggested exercising at least 400 meters (about 1/4 of a mile) away from highways and major roads.
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Also consider avoiding exercise outdoors when air quality is poor such as when the AQI is >100.
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However, because of the many health benefits of exercise, please consider talking to a health care provider regarding what is best for you.
Why should I close my windows when air quality is poor?
Closing windows and using air conditioning can significantly reduce outdoor air pollution from coming inside your home.
However, please consider if these strategies lead to other problems like heat and high temperatures or high indoor air pollution levels.
What are sources of indoor air pollution to be aware of?
Fuel-burning combustion applications (including wood or coal stoves), space heaters, and gas ranges and ovens can emit air pollution inside your home. Tobacco products, like cigarettes, can also create air pollution. In addition, radon is a harmful gas that can enter your home through cracks in your foundation.
Where can I learn more about other strategies to protect myself from air pollution?
Resources can be found here.
Sensitive groups
What are sensitive groups?
Sensitive groups refer to people are more likely to be affected by air pollution and would benefit the most from reducing exposure to air pollution.
Are people with asthma or COPD in a sensitive group?
Yes, people with certain underlying medical conditions, such as asthma and COPD, are more sensitive to air pollution. Air pollution has been shown to worsen symptoms among people with asthma or COPD. Health effects of air pollution are described here.
Are people who are pregnant in a sensitive group?
Yes, people who are pregnant are considered sensitive because of the changes happening in their bodies. Studies have shown that air pollution is associated with negative outcomes such as low birth weight and preterm birth. Health effects of air pollution are described here.
What are other sensitive groups?
Other sensitive groups include people with heart disease, lung disease, or diabetes, people who are 65 years old and older, children younger than 18 years old, and people experiencing poverty.
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As research continues to grow, other sensitive groups may be discovered.
Where can I learn more about sensitive groups?
Resources can be found here.
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Making cleaner air
What are steps I can take to reduce air pollution levels?
You can consider using environmental-friendly ways to get around. For example, walk or bike short distances. Use public transportation or carpool.
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In addition to taking these actions yourself, you can help to advocate for policies that create infrastructure and incentives for clean air measures. For example, more green space and parks help to reduce air pollution levels.
Where can I learn more about how to make the air cleaner?
Resources can be found here.​
