Today’s the day to start thinking about air quality.

What can you do? Pay attention to the Air Quality Index (AQI). The AQI is a tool that tells you when high levels of air pollution are predicted and tells you how air pollution affects your health. Finding the AQI is easy. 

The AQI is easy to use. If the AQI predicts a “Code Orange” (unhealthy for sensitive groups) day don’t cancel your plans—use the AQI to help you plan a better time or place for them.

The AQI tells you about five major air pollutants in the U.S. that are regulated by the US Environmental Protection Agency, including ozone and particle pollution. Ozone and particle pollution may harm the health of hundreds of thousands of Americans each year.

Ozone and Particle Pollution

Let’s say that the ozone level where you live is predicted to be Code Orange tomorrow. If you’re a runner—even if you’re healthy—that air quality could hurt you. Using the AQI, you can plan your run for when ozone levels will be lower, shorten your run or walk instead, or run on a treadmill indoors.

Particle pollution has been linked to heart attacks and strokes, and even death in people with heart disease. On a day when particle pollution will be at Code Orange, do something less intense. Walk instead of run, or weed your garden instead of doing heavier work.

Use the AQI Wherever You Go

Don’t forget to check the AQI when you’re on vacation or travel. No matter where you go, you can always access the AQI.

Ozone

Ozone is a gas that you cannot see or smell. Ozone occurs naturally in the sky about 10 to 30 miles above the earth's surface. Sometimes, this ozone is called "good ozone" because it forms a layer that protects life on earth from the sun's harmful rays.

Ground-level ozone, on the other hand, can be bad for your health and the environment. Ground-level ozone forms when pollutants from cars and trucks, power plants, factories, and other sources come in contact with each other in heat and sunlight. Factors such as weather conditions and intensity of sunlight also play a part in how ozone is formed. Ground-level ozone is one of the biggest parts of smog, and it is usually worse in the summer months.

Many urban areas tend to have higher levels of ground-level ozone. However, rural areas have ground-level ozone, too. Wind carries ozone and the pollutants that form it hundreds of miles from their original sources, and rural areas have sources of ozone that contribute to this problem.

Ozone and Health

When ozone levels are very high, everyone should be concerned about ozone exposure. But ozone bothers some people more than others, mainly when they are outside. People in these groups may feel the effects of ozone when they are outside for short periods of time, even if they are only doing light activities. Those most likely to be bothered by ozone include

• people with asthma or lung disease because they will feel the effects of ozone sooner and at lower ozone levels than less-sensitive people.
• children who spend a lot of time outdoors. Children are also more likely than adults to have asthma, which may be aggravated when they breathe in ozone. Being exposed to ozone for short periods of time over many years may cause children to have more breathing problems as adults.
• older adults because they are more likely to have heart or lung disease.
• active people of all ages who exercise or work hard outside because they are in contact with ozone more than people who spend more time indoors.
• infants because their lungs continue to develop after birth and can be impacted by air pollutants.

Many scientific studies have linked ground-level ozone contact to such varied problems as

• aggravation of asthma, bronchitis, and emphysema
• coughing and pain when taking a deep breath;
• higher chance of getting respiratory illness such as pneumonia or bronchitis;
• lung and throat irritation; and
• wheezing and breathing difficulties during exercise or outdoor activities.

As a result of these studies, scientists know that breathing in too much ozone can increase events such as

• use of asthma medication,
• absences from school,
• visits to the emergency room and hospital admissions, and
• premature death from heart and lung disease.

Protect yourself and your family

EPA's Air Quality Index, or AQI, is a tool to help you quickly learn when air pollution is likely to reach unhealthy levels. Local TV stations, radio programs, and newspapers carry these air quality forecasts to tell you when particle levels are likely to be unhealthy. You can use the AQI to plan your daily activities to reduce exposure to ozone.

Your exposure to ozone depends mainly on where you live and work and how much time you spend outside. When ozone levels are high, you can

• reduce the amount of time you spend outside;
• plan outdoor activities when ozone levels are lower, usually in the morning and evening;
• do easier outdoor activities, such as walking instead of running; and
• plan indoor activities.

Particulate Matter

Particle pollution, or particulate matter, consists of particles that are in the air, including dust, dirt, soot and smoke, and little drops of liquid. Some particles, such as soot or smoke, are large or dark enough to be seen. Other particles are so small that you cannot see them.

Particle pollution can come from primary or secondary sources. A primary source, such as wood stoves or forest fires, lets off particle pollution directly. A secondary source lets off gases that react and form particles. Examples of secondary sources are coal fires and power plants. Particle pollution also comes from motor vehicles, factories, and construction sites. These can be primary or secondary sources. Particle pollution can be a problem at different times of the year, depending on where you live.

Particle pollution includes

• coarse particles that are between 2.5 and 10 micrometers,
• fine particles that are between 0.1 micrometers and 2.5 micrometers; also known as PM2.5, and
• ultrafine particles that are smaller than 0.1 micrometers.

Particles bigger than 10 micrometers can irritate your eyes, nose, and throat but do not usually reach your lungs. Ten micrometers is about seven times thinner than one human hair.

Fine and ultrafine particles are the most concerning because they are most likely to cause health problems. Their small size allows them to get into the deep part of your lungs and even into your blood.

Particulate Matter and Health

Being exposed to any kind of particulate matter may cause

• increased emergency department visits and hospital stays for breathing and heart problems,
• worsened asthma symptoms,
• adverse birth outcomes,
• breathing problems,
• decreased lung growth in children,
• lung cancer, and
• early deaths.

People who are at the highest risk of being bothered by particulate matter include

• people with heart or lung diseases because they will feel the effects of particulate matter sooner and at lower ozone levels than less-sensitive people.
• older adults because they may not know they have lung or heart disease. When particle levels are high, older adults are more likely than young adults to have to go to the hospital or die because the exposure to particle pollution has made their heart or lung disease worse.
• children because they are still growing and spend more time at high activity levels. When children come in contact with particle pollution over a long period of time they may have problems as their lungs and airways are developing. This exposure may put them at risk for lowered lung function and other respiratory problems later in life. Children are more likely than adults to have asthma and other respiratory problems that can worsen when particle pollution is high.
• infants because their lungs continue to develop after birth and can be impacted by air pollutants.

Protect yourself and your family

EPA's Air Quality Index, or AQI, is a tool to help you quickly learn when air pollution is likely to reach unhealthy levels. Local TV stations, radio programs, and newspapers carry these air quality forecasts to tell you when particle levels are likely to be unhealthy. You can use the AQI to plan your daily activities to reduce exposure to particle pollution.

When particle pollution levels are high, you can

• reduce the amount of time you spend outside;
• do easier outdoor activities, such as walking instead of running or using a riding lawn mower instead of a push mower; and
• exercise away from roads and highways. Particle pollution is usually worse near these areas.

If you have one of the following diseases, you may experience some effects from particle pollution:

Lung disease

• You may not be able to breathe as deeply or strongly as you usually do.
• You may cough more, have chest pain, wheeze, feel like you can't catch your breath, or be tired more than usual.

Heart disease

• Coming in contact with particle pollution can cause serious problems in a short period of time, such as a heart attack without any warning signs.
• Symptoms, including chest pain or tightness, fast heartbeat, feeling out of breath, and feeling tired more than usual, may be signs of a serious problem. If you have any of these signs, follow your doctor's advice and contact your doctor if the symptoms last longer than usual or worsen.

Asthma

• Follow your asthma management plan when particle levels are high.

Benzene

Benzene is a chemical that is a colorless or light yellow liquid at room temperature. It has a sweet odor and is highly flammable. It evaporates into the air very quickly, but its vapor is heavier than air and may sink into low-lying areas. It dissolves only slightly in water and will float on top of water.

Benzene is formed from both natural processes and human activities. Natural sources of benzene include volcanoes and forest fires. It is also a natural part of crude oil, gasoline, and cigarette smoke. This chemical is widely used in the United States, and ranks in the top 20 chemicals for production volume.

Some industries use benzene to make other chemicals that are used to make plastics, resins, and nylon and synthetic fibers. Benzene is also used to make some types of lubricants, rubbers, dyes, detergents, drugs, and pesticides.

Outdoor air contains low levels of benzene from tobacco smoke, gas stations, motor vehicle exhaust, and industrial emissions. Indoor air generally contains levels of benzene higher than those in outdoor air. The benzene in indoor air comes from products that contain benzene such as glues, paints, furniture wax, and detergents. The air around hazardous waste sites or gas stations can contain higher levels of benzene than in other areas. People working in industries that make or use benzene may be exposed to the highest levels of it. Tobacco smoke is also a major source of benzene exposure.

Benzene and Health

People who breathe in high levels of benzene may develop the following signs and symptoms within minutes to several hours:

• Drowsiness
• Dizziness
• Rapid or irregular heartbeat
• Headaches
• Tremors
• Confusion
• Unconsciousness
• Death (at very high levels)

Eating foods or drinking beverages containing high levels of benzene can cause the following symptoms within minutes to several hours:

• Vomiting
• Irritation of the stomach
• Dizziness
• Sleepiness
• Convulsions
• Rapid or irregular heartbeat
• Death (at very high levels)

If a person vomits because of swallowing foods or beverages containing benzene, the vomit could be sucked into the lungs and cause breathing problems and coughing. Direct exposure of the eyes, skin, or lungs to benzene can cause tissue injury and irritation. Showing these signs and symptoms does not necessarily mean that a person has been exposed benzene.

Long-term exposure

The major effect of benzene from long-term exposure is on the blood. (Long-term exposure means exposure of a year or more.) Benzene causes harmful effects on the bone marrow and can cause a decrease in red blood cells, leading to anemia. It can also cause excessive bleeding and can affect the immune system, increasing the chance for infection.

Some women who breathed high levels of benzene for many months had irregular menstrual periods and a decrease in the size of their ovaries. It is not known whether benzene exposure affects the developing fetus in pregnant women or fertility in men.

Animal studies have shown low birth weights, delayed bone formation, and bone marrow damage when pregnant animals breathed benzene.

The Department of Health and Human Services (DHHS) has determined that benzene causes cancer in humans. Long-term exposure to high levels of benzene in the air can cause leukemia, cancer of the blood-forming organs.

Protect yourself and your family

First, if the benzene was released into the air, get fresh air by leaving the area where the benzene was released. Moving to an area with fresh air is a good way to reduce the possibility of death from exposure to benzene in the air.

• If the benzene release was outside, move away from the area where the benzene was released.
• If the benzene release was indoors, get out of the building.

If you are near a release of benzene, emergency coordinators may tell you to either evacuate the area or to "shelter in place" inside a building to avoid being exposed to the chemical.

If you think you may have been exposed to benzene, you should remove your clothing, rapidly wash your entire body with soap and water, and get medical care as quickly as possible.

Formaldehyde

At room temperature, formaldehyde is a colorless, flammable gas that has a distinct, pungent smell. It is produced by both human and natural sources. Small amounts of formaldehyde are naturally produced by plants, animals, and humans.

Formaldehyde is used in the production of fertilizer, paper, plywood, and urea-formaldehyde resins. It is also used as a preservative in some foods and in many products used around the house, such as antiseptics, medicines, and cosmetics.

The primary way you can be exposed to formaldehyde is by breathing air containing it. Releases of formaldehyde into the air occur from industries using or manufacturing formaldehyde, wood products (such as particle-board, plywood, and furniture), automobile exhaust, cigarette smoke, paints and varnishes, and carpets and permanent press fabrics. The highest potential exposure occurs in the formaldehyde-based resins industry.

Formaldehyde and Health

Everyone is exposed to small amounts of formaldehyde in air and some foods and products. Nasal and eye irritation, neurological effects, and increased risk of asthma and/or allergy have been observed in people who breathe in low levels of formaldehyde. Eczema and changes in lung function have been observed in people who breathe in formaldehyde at slightly higher levels.

The Department of Health and Human Services (DHHS) has determined that formaldehyde causes cancer in humans.

Protect yourself and your family.

Formaldehyde is usually found in the air, and levels are usually higher indoors than outdoors. Opening windows and using fans to bring fresh air indoors are the easiest ways to lower levels in the house. Not smoking and not using unvented heaters indoors can lower the formaldehyde levels.

Formaldehyde is given off from a number of products used in the home. Removing formaldehyde sources in the home can reduce exposure. Providing fresh air, sealing unfinished manufactured wood surfaces, and washing new permanent press clothing before wearing can help lower exposure. Read more information about formaldehyde here.

Millions of people live in areas where air pollution can cause serious health problems. Local air quality can affect our daily lives. Like the weather, it can change from day to day. EPA developed the Air Quality Index, or AQI, to make information available about the health effects of the five most common air pollutants, and how to avoid those effects.

Ground-level ozone and airborne particles are the two pollutants that pose the greatest threat to human health in this country. You can find information about these pollutants in the documents listed below. Ozone, also known as smog, can irritate your respiratory system, causing coughing, irritation in your throat or a burning sensation in your airways. It can reduce lung function, so that you may have feelings of chest tightness, wheezing, or shortness of breath. Ozone can aggravate asthma and trigger asthma attacks. People at greater risk from ground-level ozone are people with lung diseases, such as asthma, older adults and children and adults who are active outdoors.

Particle pollution, also known as particulate matter, is composed of microscopic solids or liquid droplets that are so small that they can get deep into the lungs and cause serious health problems. When exposed to these small particles, people with heart or lung diseases and older adults are more at risk of hospital and emergency room visits or, in some cases, even death from heart or lung disease. Even if you are healthy, you may experience temporary symptoms from exposure to elevated levels of particles. Symptoms may include: irritation of the eyes, nose and throat; coughing; phlegm; chest tightness; and shortness of breath. At greatest risk from particle pollution are people with heart or lung disease, older adults (possibly because they may have undiagnosed heart or lung disease), and children.

Air quality affects the air we breathe. There are many factors that can lead to poor air quality, but the two most common are related to elevated concentrations of ground-level ozone or particulate matter.

Ground level ozone forms when nitrogen oxides from sources like vehicle exhaust and industrial emissions react with organic compounds in the presence of heat and sunlight. Per EPA, ozone can cause a number of health problems, including coughing, breathing difficulty, and lung damage. Exposure to ozone can make the lungs more susceptible to infection, aggravate lung diseases, increase the frequency of asthma attacks, and increase the risk of early death from heart or lung disease.

Particulate matter in the air consists of solid and liquid particles including smoke, dust and other aerosols, some of which are directly emitted and others are resulting from chemical transformations. The sources of these particles are numerous- including vehicles, factories, power plants, fires,  other natural phenomena and  human activities. Particle pollution is linked to a number of health problems, including coughing, wheezing, reduced lung function, asthma attacks, heart attacks, strokes and even early death.

The weather can have a significant impact on air quality since different aspects of the weather affect the amounts of ozone and particulates that are present in a specific area. Sunshine, rain, higher temperatures, wind speed, air turbulence, and mixing depths all affect pollutant concentrations.

• Sunshine can cause some pollutants to undergo chemical reactions, resulting in the development of smog

• Higher air temperatures can speed up chemical reactions in the air

• Rain typically results in less pollution since it washes away particulate matter and can also wash out pollutants that are dissolvable

• Wind speed, air turbulence, and mixing depth all affect how pollutants disperse, or spread out from an area

National Weather Service provides model forecast guidance for ozone, dust and fine particulate matter twice daily and smoke predictions once daily for next 48 hours. State and local agencies use NWS model guidance to issue air quality forecasts that weather forecast offices (WFOs) help disseminate. Air quality forecasts of unhealthy (code orange) or worse air quality that are shared with WFOs get displayed on NWS warning maps as air quality alerts. When Air Quality Alerts are in effect, there are many actions you can take to stay safe and protect your health.  

• Stay informed about air quality conditions in your area.

• Choose a less-strenuous activity

• Shorten and take more breaks during outdoor activity

• Reschedule activities to the morning or to another day

• Move your activity inside where ozone levels are usually lower

• Spend less time near busy roads

If you would like to help reduce air pollution, you can take the following measures:

• Eliminate tobacco smoke

• Reduce your use of wood stoves and fireplaces

• Don’t burn candles, leaves, garbage, plastic or rubber

• Use HEPA air filters and air cleaners designed to reduce particles

• Drive less: carpool, use public transportation, bike or walk

• Keep car, boat and other engines tuned

• Inflate tires to the recommended pressure

• When refueling: stop when the pump shuts off, avoid spilling fuel, and tighten your gas cap

• Use low-VOC paint and cleaning products, and seal and store them so they can’t evaporate

• Choose energy saving appliances

• Set thermostats higher in summer and lower in winter

• Turn off lights you are not using

What is the U.S. Air Quality Index (AQI)?

The U.S. AQI is EPA’s index for reporting air quality.

How does the AQI work?

Think of the AQI as a yardstick that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality.

For each pollutant an AQI value of 100 generally corresponds to an ambient air concentration that equals the level of the short-term national ambient air quality standard for protection of public health. AQI values at or below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is unhealthy: at first for certain sensitive groups of people, then for everyone as AQI values get higher.

The AQI is divided into six categories. Each category corresponds to a different level of health concern. Each category also has a specific color. The color makes it easy for people to quickly determine whether air quality is reaching unhealthy levels in their communities.

Five major pollutants

EPA establishes an AQI for five major air pollutants regulated by the Clean Air Act. Each of these pollutants has a national air quality standard set by EPA to protect public health:

• ground-level ozone
• particle pollution (also known as particulate matter, including PM2.5 and PM10)
• carbon monoxide
• sulfur dioxide
• nitrogen dioxide

Use the Air Quality Index (AQI) to learn more about your local air quality and the best times for your outdoor activities.

The U.S. Air Quality Index – daily index

What it is: The U.S. Air Quality Index, or AQI, is EPA’s tool for communicating daily air quality. It uses color-coded categories and provides statements for each category that tell you about air quality in your area, which groups of people may be affected, and steps you can take to reduce your exposure to air pollution. It’s also used as the basis for air quality forecasts and current air quality reporting.

Who issues it: EPA has issued a national index for air quality since 1976 to provide an easy-to-understand daily report on air quality in a format that’s the same from state to state. The AQI as we know it today was issued in 1999; it’s been updated several times since to reflect the latest health-based air quality standards.

What pollutants it covers: There’s a U.S. AQI for five major pollutants that are regulated by the Clean Air Act: ozone, particle pollution (also called particulate matter), carbon monoxide, nitrogen dioxide and sulfur dioxide. The AQI for each pollutant is generally based on the health-based national ambient air quality standard for that pollutant and the scientific information that supports that standard.

What time frame it covers: It varies by pollutant. The ozone AQI is an 8-hour index; for particle pollution, it’s 24 hours.

Where can you get it: Metro areas with a population of more than 350,000 are required to report the daily AQI. Many more areas report it as a public service. You can find the daily AQI on AirNow and on state and local agency websites. Some agencies also report the AQI via their local news media, or by telephone hotlines.

How to use it: Check the previous day’s AQI to learn more about air quality in your community.

AQI Forecasts

What they are: A prediction of the day’s AQI. Forecasts usually are issued in the afternoon for the next day.

Who issues them: State and local air quality forecasters across the country. They use a number of tools – including weather forecast models, satellite images, air monitoring data, and computer models that estimate how pollution travels on the air. They also use their own knowledge of how pollution behaves in certain communities to issue the air quality forecast for the next day.

What pollutants they cover: Most state and local air quality forecasters issue forecasts for ozone and particle pollution, which are two of the most widespread pollutants in the U.S. A few areas also issue forecasts for nitrogen dioxide and carbon monoxide.

What time frame they cover: In most areas, AQI forecasts focus on the next day. For ozone, an AQI forecast focuses on the period during the day when average 8-hour ozone concentrations are expected to be the highest. For PM, the forecast predicts the average 24-hour concentration for the next day.

What they tell you: AQI forecasts tell you what the next day’s AQI is expected to be, which groups of people may be affected, and steps individuals can take to reduce their exposure to air pollution.

Where you can get them: State and local agencies provide AQI forecasts as a public service. You can find forecasts for your area on AirNow, on state, local and tribal air agency websites, in your local news media, and through some national media outlets.

How to use them: Use AQI forecasts to help you plan your outdoor activities for the day. Much like a weather forecast lets you know whether to pack an umbrella, an air quality forecast lets you know when you may want to change your outdoor activities to reduce the amount of air pollution you breathe in. Many forecasters also provide a “forecast discussion,” which lets you know when pollution is expected to be highest during the day – and if there are times when air quality is expected to be better.

Some areas issue AQI forecasts for several days, to help you plan. But because things can change, it’s a good idea to check the forecast every day.

The NowCast AQI

What it is: The NowCast AQI shows your current air quality using the AQI colors and scale.

Who issues it: EPA uses two algorithms, called “NowCasts,” to relate hourly readings from air quality monitors to the AQI for ozone and the AQI for particle pollution.

What pollutants it covers: EPA calculates a NowCast for two pollutants: ozone and particle pollution. There is a separate algorithm for each.

What time frame it covers: The NowCast shows you air quality for the most current hour available by using a calculation that involves multiple hours of past data. The NowCast uses longer averages during periods of stable air quality and shorter averages when air quality is changing rapidly, such as during a wildfire.

What it tells you: The NowCast gives you the latest information on air quality where you are. Because air quality can change during the day, you can expect to see the NowCast AQI change, too.

Where you can get it: Anywhere you see “current air quality” information on AirNow.gov -- that has been calculated using the NowCast. The AirNow app and the AirNow widget use the NowCast, too. EPA also provides current air quality information to state and local agencies, media, app developers and others, through its Application Programming Interface (also called an API).

How to use it: Check the NowCast AQI to see if now is a good time for your outdoor activity. Even on days when the AQI forecast isn’t good, there may be times during the day when air quality is OK for outdoor activity.

What is an air sensor?

Air sensor is a simplified way of referring to a class of technology that has expanded on the market in recent years and has common traits of directly-reading a pollutant in the air, being smaller in size, and often sold at a price that supports a wider number of monitoring locations than possible in the past. Many groups refer to this class of technology as “low-cost air sensors,” “air sensor devices,” and “air quality sensors.”

These technologies vary in their physical design, including which types of air pollutants are measured, how data are managed, whether or not the system is weatherproof, and how the technology is powered. Some air sensors are designed for stationary use, while others are designed to be mounted to vehicles or worn by the user. There is also a great deal of variety in how these technologies are priced, with differences from business to business regarding whether the sensors are sold versus leased, replacement and maintenance plans, and how data are managed and owned.

What kind of air pollutants can be measured with air sensors?

Air sensors currently on the market measure a wide variety of air pollutants, but not all air pollutants. However, the key challenge is to understand whether the air sensor will measure the target pollutant in a mixture of other pollutants and measure the target pollutant at the expected concentration range for the application of interest. Testing in real-world conditions by EPA and outside groups have focused primarily on the growing number of air sensors that measure the six criteria pollutants regulated under the National Ambient Air Quality Standards.

How is air sensor technology being used?

Potential uses for new air sensor technologies include, but are not limited to:

• Science education
• Supplementing regulatory air quality measurements
• Conducting research
• Measuring local air quality to better understand sources of pollution
• Locating leaks at industrial facilities
• Emergency response

​Can air sensor data be used for National Ambient Air Quality Standard (NAAQS) compliance?

EPA’s Office of Air and Radiation has addressed this question in a June 22, 2020 memorandum. You can read the memo here.

Are sensor data as good as data from regulatory monitors?

While air sensors are useful for providing general information about air quality, air sensors have a number of limitations that could include occasionally reporting questionable data points and a bias that may result in data that systematically over- or under-estimates the actual pollutant concentration.

What are the common challenges experienced by users of air sensors?

• Air sensors may not be sufficiently selective or sensitive for the target pollutant of interest – real-world testing information can help the user determine whether a certain air sensor will provide data meeting their application needs.
• Low and high temperatures, as well as high humidity levels, may cause inaccurate readings.
• Air sensors may be inaccurate and therefore may require field calibration to give more accurate data.
• Not all air sensors are weatherproof – some air sensors need a physical enclosure in order to protect them from weather conditions.
• Many air sensors for gases become less sensitive to the target pollutant over time so their readings will become less accurate. Some air sensors are only usable for one to two years.
• Many air sensors do not display data on a screen in real-time. The user may need to download the data and/or view it on a computer with specific software or an app.
• Air sensors may require specific data communication methods, like WiFi, cellular, or Bluetooth.
• Air sensors may not collect data 100 percent of the time. Technology can malfunction, power supplies can go out, and weather can interfere with readings. Because of this, it is important to check sensors frequently to make sure they are running correctly.

Two key air pollutants can affect asthma. One is ozone (found in smog). The other is particle pollution (found in haze, smoke, and dust). Studies show that when ozone and particle pollution are in the air, adults and children with asthma, and other lung diseases, are more likely to have symptoms.

Studies also show that air pollution can trigger heart attacks, stroke, and irregular heart rhythms—especially in people who are already at risk for these conditions. Also, for people with a medical condition called heart failure, air pollution can further reduce the ability of the heart to pump blood the way that it should. Particle pollution is the pollutant of greatest concern for triggering these effects. 

Smoke is made up of a complex mixture of gases and fine particles produced when wood and other organic materials burn. The biggest health threat from smoke is from fine particles. These microscopic particles can get into your eyes and respiratory system, where they can cause health problems such as burning eyes, runny nose, and illnesses such as bronchitis. Fine particles also can aggravate chronic heart and lung diseases - and even are linked to premature deaths in people with these conditions.

If you are healthy, you're usually not at a major risk from short-term exposures to smoke. Still, it's a good idea to avoid breathing smoke if you can help it. Everyone should take the steps below when wildfires are present.

Use common sense. If it looks smoky outside, it's probably not a good time to mow the lawn or go for a run. And it's probably not a good time for your children to play outdoors.

Pay attention to local air quality reports.Stay alert to smoke-related news coverage or health warnings.

Visit AirNow to find out the Air Quality Index in your area. As smoke gets worse, the amount of particles in the air changes - and so do the steps you should take to protect yourself. AirNow recommends precautions you can take to protect your health when air pollution gets bad.

If you are advised to stay indoors, take steps to keep indoor air as clean as possible. When smoke levels are high, try to avoid using anything that burns, such as wood fireplaces, gas logs, gas stoves - and even candles! Don't vacuum. That stirs up particles already inside your home. And don't smoke. That puts even more pollution in your lungs, and in the lungs of people around you.

If you have asthma or other lung disease, make sure you follow your doctor's directions about taking your medicines and following your asthma management plan. Call your doctor if your symptoms worsen.

Run your air conditioner if you have one. Keep the fresh air intake closed and the filter clean to prevent bringing additional smoke inside. Note: If you don't have an air conditioner, staying inside with the windows closed may be dangerous in extremely hot weather. In these cases, seek alternative shelter.

If you have heart or lung disease, if you are an older adult, or if you have children, talk with your doctor about whether and when you should leave the area. When smoke is heavy for a prolonged period of time, fine particles can build up indoors, even though you may not be able to see them.

As people age, their bodies are less able to compensate for the effects of environmental hazards. Air pollution can aggravate heart disease and stroke, lung diseases such as chronic obstructive pulmonary disease and asthma, and diabetes. This leads to increased medication use, more visits to health care providers, admissions to emergency rooms and hospitals, and even death.

Ozone and Particulate Matter (PM) (especially smaller, fine particle pollution called PM 2.5) have the greatest potential to affect the health of older adults. Fine particle pollution has been linked to premature death, cardiac arrhythmias and heart attacks, asthma attacks, and the development of chronic bronchitis. Ozone, even at low levels, can exacerbate respiratory diseases.

Studies show that air pollution can trigger heart attacks, strokes and worsen heart failure in people who are at risk for these conditions. If you have a heart condition, you could benefit by reducing your exposure to high levels of air pollution.

When are air pollution levels high?

• Any time of year
• When weather is calm
• Near busy roads
• In urban areas
• In industrial areas
• When there is smoke

Are you at risk?

Greater risk if you have or have had:

• Coronary artery disease
• Angina (chest pain)
• A heart attack
• Bypass surgery or an angioplasty
• Heart failure
• An internal cardiac defibrillator
• A stroke or transient ischemic attack
• Blockages in the arteries of the neck or legs

Steps to Protect Your Heart

When pollution is high, you can reduce the amount of particle pollution you inhale

• Know when and where particle pollution levels may be unhealthy. Particle pollution levels can be high at any time of the year. They can be higher near busy roads or industrial areas or during rush hour traffic. When there is smoke in the air from forest fires, burning vegetation or wood stoves, higher levels of particle pollution are present.
• Check the Air Quality Index, which provides forecasts of daily air quality.  This index provides six color-coded categories that show different levels of health concern for air pollution levels by state or zip code.
• Plan activities when and where pollution levels are lower. When particle levels outdoors are unhealthy, delay activity or exercise until the air is cleaner or move the activity indoors.
• Change your activity level. When the air is polluted, reduce activity. Go for a walk rather than a jog, for example. Delay outdoor activity when the air is polluted or exercise indoors.
• Reduce overall risk of heart disease or stroke. Make healthy lifestyle changes as described above.
• Know the warning signs of heart attack or stroke. If you feel symptoms, even if they go away, stop any activity and seek medical help immediately.​

How to Reduce your Risk?

Reduce your overall risk of heart disease and stroke

• Eat healthy foods
• Control blood pressure
• Control cholesterol levels
• Exercise more (first check with your health care provider)
• Stop smoking
• Take aspirin and heart medication as directed
• Talk to your health care provider about treatment

Warning Signs of a Heart Attack

• Chest discomfort (uncomfortable pressure, fullness, squeezing, or pain in the center of the chest that lasts more than a few minutes or goes
  away and comes back)
• Discomfort in other areas of the upper body (pain or discomfort in one or both arms, the back, neck, jaw, or stomach)
• Shortness of breath
• Other signs may include breaking out in cold sweats, nausea, or light-headedness

Warning Signs of a Stroke

• Sudden numbness or weakness in the face, arm or leg (especially on one side of the body)
• Confusion, trouble speaking or understanding
• Problems seeing
• Dizziness, loss of balance or coordination, or trouble walking
• Severe headache with no known cause

Having clean air to breathe is necessary for good health. Poor air quality reduces quality of life. Some air pollutants are irritants. Some smell bad. Some air pollutants can cause respiratory disease or even cancer.  Air quality is important both indoors and outdoors. Ground level ozone, particulate matter and allergens are common outdoor air pollutants. Secondhand smoke, mold and radon are common indoor air pollutants.  Poor air quality may limit people’s ability or opportunity to be physically active. People with preexisting medical conditions such as asthma, emphysema or COPD are at greater risk from poor air quality. Good air quality is an important livability indicator for a healthy community. 

Why is clean air important to health?

Air in its purest state is best suited for the essential task sustaining life.  Air pollution is a major environmental risk to health. Air pollution can trigger heart attacks or strokes. In fact, one in three Americans has heart disease which can be worsened by air pollution. Breathing clean air can lessen the possibility of disease from stroke, heart disease, lung cancer as well as chronic and acute respiratory illnesses such as asthma. Lower levels of air pollution are better for heart and respiratory health both long- and short-term. Learn about the many ways air pollution can harm your health and the atmosphere.  Find out what you can do to help protect the air we breathe.

What about physical activity limitations and air quality forecasts?

The Air Quality Index (AQI) is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The AQI focuses on health affects you may experience within a few hours or days after breathing polluted air.

Think of the AQI as a yardstick that runs from 0 to 500. The higher the AQI value the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 represents good air quality with little potential to affect public health, while an AQI value over 300 represents hazardous air quality.

An AQI value of 100 generally corresponds to the national air quality standard for the pollutant, which is the limit the U.S. Environmental Protection Agency (EPA) has set to protect public health. AQI values below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is considered to be unhealthy at first for certain sensitive groups of people, then for all people as AQI values get higher.

Air quality forecasts provide information to the public about ground level ozone and PM2.5, which is a measure of particulate matter 2.5 microns or less in size, and their associated health effects. Pollutant-specific health effects statements and cautionary statements are provided along with the forecasts.

A forecast is used to alert those in an area that may be sensitive to elevated levels of ozone so that they can make decisions related to their daily activities. However, the air quality forecast is exactly what it says—it is a forecast. Just as television meteorologists sometimes miss whether it will be cloudy or sunny in our area, sometimes forecasters will miss the actual PM2.5 and ozone category or color code for the day. If there is any question as to how a day will be forecast, every effort is made to err on the side of over-predicting the expected maximum concentration as the intent of this forecasting process is to protect the health of citizens.

What’s a permit; how does it protect me?

An air permit limits how much of a contaminant can be emitted from a source into the air that we breathe.  The requirements for limiting the emission of airborne contaminants look at the health effects on people.  Air permits can also consider effects on animals, vegetation and property.  Variables include the amount of the pollutant and point of the potential exposure.  When multiple sources of a pollutant exist in an area, a limitation of the emission from each source must be enforced, and the individual contribution to the total pollutant load in the area must be reduced.  This is done to comply with EPA ambient air quality standards. Limiting the contact is done by the application of emission standards.

Ambient air quality standards are further intended to promote the maximum use of property. When the problems involved are esthetic in nature, an economic balance must be achieved. When a health hazard is involved, there can be no compromise and the standards must be upheld.

What are common air pollutants?

Common outdoor air pollutants include byproducts from automobile emissions like particulate matter (PM), nitrogen dioxide (NO2), sulfur dioxide (SO2) and ozone (O3).  Other outdoor air pollutants are allergens like pollen and molds.

Common indoor air pollutants include environmental tobacco smoke, fumes from paints and solvents, radon, carbon monoxide, formaldehyde, animal hair and dander, molds, bacteria, pollen and combustion gases.

What is a non-attainment zone?

According to United States’ environmental law, a non-attainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970. Non-attainment areas must have and implement a plan to meet the NAAQSs, or risk losing some forms of federal financial assistance. An area may be a non-attainment area for one pollutant and an attainment area (lower than or meeting the NAAQS) for other pollutants.

Why is air quality important for development?

Reducing air pollution forms the basis of economic growth and future development.  Organizations can minimize the amount of contaminants entering the air from their facility to become more competitive and successful in their respective fields, while preserving the environment.  Conservation of air as a natural resource begins by preventing or reducing air pollution.

Who tests air quality?

The Tennessee Department of Environment and Conservation’s Division of Air Pollution Control directly serves 91 counties within the state by monitoring industries, conducting source visits, testing and monitoring air at the various stations set up across the state and other tasks. The Division of Air Pollution Control also oversees and assists in the actions of local air pollution control programs in Davidson, Hamilton, Knox and Shelby counties. If you live in Davidson, Hamilton, Knox or Shelby counties you must contact these local air programs for further air testing information.

What about indoor air quality?

Indoor air quality (IAQ) is a term which refers to the air quality within and around buildings and structures, especially with regard to the health and comfort of building occupants.  Maintaining a healthy indoor building environment is important to all aspects of life.  Healthy indoor air quality leads to greater productivity at work and school; and better health at home.

Indoor air quality can be affected by gases such as carbon monoxide, radon or volatile organic compounds.  Air quality can be reduced by particulate matter from burning wood or charcoal.  Environmental tobacco smoke, mold and ozone can also reduce air quality.

Some ways of improving indoor air quality in buildings are source control, filtration and ventilation.

What is a greenhouse gas?

Greenhouse gases in the Earth’s atmosphere absorb infrared radiation from the sun and release it. Some of the heat released reaches the earth, along with heat from the sun that has penetrated the atmosphere. Both the solar heat and the radiated heat are absorbed by the Earth and released; some is reabsorbed by greenhouse gases to continue the cycle. The more of these gases that exists, the more heat is prevented from escaping into space and, consequently, the more the earth heats. This increase in heat is called the greenhouse effect.

Common examples of greenhouse gases, listed in order of abundance, include: water vapor, carbon dioxide, methane, nitrous oxide, ozone and any fluorocarbons. Although water vapor is the most abundant greenhouse gas, it is a relatively ineffective one. Some degree of greenhouse gases in our environment is only natural. Without the greenhouse effect our ecosystem would not be possible.

Since the industrial age began in the 1750s, however, carbon dioxide alone has increased by 40%. Concerns about the greenhouse effect's contribution to global warming have prompted agreements between various governments on targets for reduction of greenhouse gas emissions.