What are the Six Levels of Air Quality?

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Air Quality Levels

As the modern world continues to expand thanks to technology and globalization, cities and industries grow and evolve with it—but so does their waste, which later leaks into the air, causing pollution. Unfortunately, exposure to these airborne particles, or pollutants, can cause major public health issues. For this reason, guaranteeing good air quality has become a priority to many governments, who have set up air monitoring quality standards to make sure that air pollution doesn’t rise to unhealthy levels, thus putting people at risk of contracting potentially dangerous diseases. 

Why is it important to monitor air quality?

Clean and safe-to-breathe air allows for life on Earth to flourish air is a vital resource for people, plants, and animals. Contaminated or unhealthy air means that it contains a significant or high concentration of pollutants that trigger air quality alarms as it may pose a risk to living creatures. Some of the most dangerous air pollutants are ozone (O3), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), and particulate matter — meaning inhalable particles that are made up of sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust or water. So, to ensure that the air quality stays unpolluted, governments and health agencies have introduced the Air Quality Index (AQI) to monitor air quality in different cities of the world.  

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What is the Air Quality Index and what are the six levels of air quality?

The Air Quality Index, or AQI, is an air quality measuring system that warns whether the outdoor air is good or bad, depending on the number of pollutants present in it, by classifying it into different categories. The AQI system gathers large amounts of data in real-time regarding the quality of the ambient air in any place and time and compiles it in a format that is easy to read for anyone who wants to see how clean or polluted the air actually is. 

Countries have different ways of measuring air pollutants, and some may focus more on some particles than others, but the goal is basically the same: monitor air quality. As seen in the United States’ AQI system, the Index is divided into six different color-coded groups that indicate the quality of the air and the level of pollution. Each category accounts for a level of concern in air quality and has assigned values that range between 0 and 500 being the highest and most dangerous ones. The six quality indicators are sorted as follows: 

  • Green (Good): AQI value is 0-50. Pollution is low and poses little or no risk. 
  • Yellow (Moderate): AQI value is 51-100. Air quality is acceptable. Some may be affected, particularly those with pre-existing lung diseases. 
  • Orange (Unhealthy for sensitive groups): AQI value is 101-150. Sensitive groups (such as the elder, children, or people with lung conditions) may experience some health issues, and the general public is less likely to be affected by exposure. 
  • Red (Unhealthy): AQI value is 151-200. Sensitive groups may experience serious health issues, and the general public will also be affected. 
  • Purple (Very unhealthy): AQI value is 201-300. Everyone is at risk of experiencing health effects. 
  • Maroon (Hazardous): AQI value is 301+. Health emergency level. Everyone is likely to experience health issues. 

What are the six major air pollutants?

air pollution

The United States’ Clean Air Act regulates six major air pollutants 

  • Ground-level ozone 
  • Carbon Monoxide 
  • Sulfur Dioxide 
  • Particulate matter (PM) 
  • Nitrogen Dioxide 
  • Lead  

The U.S. Environmental Protection Agency (EPA) is in charge of setting up AQI standards for each of these outdoor air pollutants, known as the National Ambient Air Quality Standards (NAAQS), to preserve the people’s quality of life and look after the environment. 

The EPA must therefore define areas as “meeting” (that is, quality standard is achieved) or “not meeting” (not achieved) for the standards on a national level. Each state, in accordance with the Clean Air Act, has to develop a plan to achieve and then maintain the outdoor air quality standard. In case the standard is not met, they must also develop a plan to bring up to its desired measure to guarantee that air quality is on the same level across the country.  

 What are the effects of air pollution on health?

Whether it is short or long-term exposure to air pollution, the effect on human health is still significant either way. It can affect people of any age, although certain age groups, like children or the elderly, can be more affected than others. Certain air pollutants can cause severe health issues, particularly in those with underlying conditions like asthma or heart diseases. For example, ground-level ozone causes the airways to become irritated and lead to symptoms such as wheezing, chest pain, headaches, and nausea, sending the respiratory system into overdrive and augmenting exertion and lung and chest pain. Pollutants known as Particulate Matter can actually get into the lungs and directly into the bloodstream, causing damage to the heart as well, leading to premature death in people at risk. 

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Conclusion about the Six Levels of Air Quality

Implementing an Air Quality Index is a powerful and useful way for countries to keep an eye on the number of harmful particles present in the air and ensure national air quality standards are kept. Having an AQI system has proved its benefits not only to the environment but also to the people, as it reduces or prevents the risk of exposure to air pollution and long or short-term effects that can result in sickness, even deadly diseases. However, an AQI by itself is not enough, as it must be accompanied by policies and laws that regulate air quality, not just measure it, and set action plans in motion to meet the desired standards. It is a collective effort, not just from governments on a national and local level, but it requires small and large businesses, industries, and the people to carry out sustainable practices that ensure safe ambient air for all. We all have to remember that monitoring the environment is a good thing to do to respect it and live in harmony.  

Frequently Asked Questions About the Six Levels of Air Quality

Most of the pollution in the air is caused by human activities, such as: burning fossil fuels to generate electricity; smog and soot that come from vehicles, factories and power plants, engines, or anything that combusts fossil fuels; and lastly, vehicle exhausts, which release large concentrations of polluting chemicals such as carbon monoxide and sulfur dioxide into the environment. On the other hand, natural sources of air pollution are volcanic eruptions, wildfires and dust storms. 

In the United States, the Clean Air Act has been a crucial instrument for monitoring air pollution since it was passed in 1970. The CAA is the federal law that regulates air emissions from stationary and mobile sources. It also monitors the emissions of hazardous air contaminants. Therefore, ensuring that this environmental law remains intact and properly enforced will be key to monitoring and improving the air quality. 

Created in the 1970s by the US federal government, the Environmental Protection Agency (EPA) is the entity in charge of monitoring air quality and pollution. Its main duties are the protection of the people and the environment from major health risks, as well as sponsoring and conducting research, and developing and enforcing environmentally friendly regulations. 

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