Explanations 
Flashcards 
StudySmarter AI 
Notes 
Study Plans 
Study Sets 
Exams 
Magazine 
Find a job 
Mobile App 
Jump to a key chapter
Air Quality Meaning
Clean air is critical for society in order to live in healthy environments. On the other hand, polluted air causes many health issues in society. This will be explored later. But first, how is air quality defined?
Air quality is the way in which we state how clean or polluted the air that we breathe in is.
Across the world, there are a variety of different locations with varying air qualities. Examples of countries with good air quality include Puerto Rico, Sweden, and Finland. Whereas countries with poor air quality include Bangladesh, Chad, and Pakistan.
Fig 1. Air Pollution
Air Quality Index
The Air Quality Index (AQI) is an air quality indicator. It is used to measure how polluted the air is. Governments use the AQI to correspond air quality levels to the public, which is crucial as it prepares the public, especially those at risk of poor air quality levels.
The AQI scale ranges from 0 to 500. The lower the number, the cleaner the air and the higher the number, the more polluted the air is. There are 6 categories to the AQI, and each category is colour coded. This helps to easily identify the level of air quality at a fast rate. The table below shows the different categories of AQI.1
| AQI Range | Color | Level of Concern | Description |
| 0-50 | Green | Good | Good air quality and no risk of pollution. |
| 51-100 | Yellow | Moderate | Air quality is satisfactory but may pose risk to those with a high sensitivity to polluted air. |
| 101-150 | Orange | Unhealthy for Sensitive Groups | People with a high sensitivity to air pollution may be affected by the air quality at this level, causing some health risks, but the rest of society is less likely to be impacted. |
| 151-200 | Red | Unhealthy | All members of the public could be impacted by the air quality, especially members with a high sensitivity to pollution. |
| 201-300 | Purple | Very Unhealthy | Everyone is at risk of health impacts due to polluted air. |
| 300+ | Maroon | Hazardous | Very unhealthy air condition that poses dangerous health risks to all. |
| Table 1 |
Remember, it is important for society to be aware of due to the risks associated with poor air quality. This can alert people to days when the air quality is significantly poor, and therefore people can remain indoors on these days to prevent becoming ill, especially if they already suffer from respiratory issues such as asthma.
Air Quality Testing
The measurement of air quality is crucial in order to gather data on pollution levels. Air quality is measured through a variety of methods depending on the pollution type. As well as general inspections that measure indoor air quality, there are two main air emission monitoring systems the Environment Protection Agency use in the US. These are:
- Ambient Air Quality Monitoring – samples of air pollution are collected and compared to historical data regarding air quality in order to state how clean the air is based upon clean air standards.
- Stationary Source Emission Monitoring – samples collected at locations where high air pollution is likely, such a factories and power plants, to measure the safety of the site.
Ultimately, each method aims to inform the level of air pollution for human safety.
Types of Air Pollution
There are a variety of air pollutants (not to be confused with water and land pollutants) that lessen the quality of air. The table below shows each of these air pollutants.
| Air Pollutant | Explanation |
| Particulate Matter | This includes smoke and dust. It is the fine material produced by pollution that can be inhaled by humans and cause health issues. |
| Lead | Lead can be found in the atmosphere as fumes or even tiny particles. It is a very toxic pollutant. Lead is released into the atmosphere due to metal processing. |
| Ground Level Ozone | The ozone is critical to society as it protects the upper atmosphere. However, at ground levels, it is highly pollutant and contributes largely to smog. Smog (also referred to as smoke fog) is a high level of pollution that causes reduced visibility.
|
| Nitrogen Oxides | One of the deadliest forms of pollution. |
| Sulfur Oxides | Another gaseous pollutant. |
| Carbon Dioxide | The most heard of pollutant; carbon dioxide, is a huge contributor to global warming. |
| Carbon Monoxide | This pollutant is poisonous. It is deadly due to the fact it is colorless and odorless. |
| Hydrocarbons | This type of toxic pollutant is most commonly emitted by traffic. |
| Table 2 |
Causes of Air Pollution in Urban Areas
Air pollution can be caused by many factors. There are both natural and anthropogenic causes of air pollution.
Anthropogenic activity includes all human undertakings.
The natural causes of air pollution include:
- Forest Fires
- Volcanic Eruptions
This is because forest fires and volcanic eruptions release gases that contribute to air pollution.
Additionally, there are a higher amount of anthropogenic factors that increase air pollution, these include:
- Transportation
- Industrial Facilities
- Fossil Fuels
- Agriculture
Most of these activities commonly occur in built environments. Therefore, urban areas are more prone to lower air quality than rural areas. But how and why does this occur?
Transportation
There are multiple methods of transportation that occurs in built urban environments such as cities, ranging from cars to trains to planes. Each of these modes of transport contributes to poor air quality by emitting pollutant gases, such as nitrogen oxides, particulate matter, hydrocarbons, carbon dioxide, and carbon monoxide. Since many cities have high amounts of transportation, along with a high density of people, there is often congestion and traffic. This can lead to further air pollution as the transportation emits harmful gases whilst in congested traffic. In fact, transportation contributes to the emission of about 27% of all greenhouse gases in the US.2
Industrial Activity
Industrial activity is another major contributor to pollution. As industrial advancement took place throughout the 20th century, an increase in industrial emissions and pollutants occurred.
Chemical waste, pesticides, radioactive materials, and fossil fuels (as well as many gases) are all pollutants that occur because of industrial activity.
Fossil Fuels
Fossil fuels are major contributors to poor air quality. Coal, oil, and gas are the main fossil fuels that produce pollution. Burning these fossil fuels, which is done to generate energy, releases pollution into the atmosphere. Fossil fuels are used largely in urban environments because buildings and infrastructure require the energy fossil fuels provide in the form of electricity and heating.
Fig 3. Fossil Fuel From Industrial Activity
Indoor air pollution, such as secondhand smoke, indoor particulate matter, and radon can also be considered as types of pollution that are often found in urban environments. These pollutants occur inside houses in urban locations such as cities.
Agricultural
Although not considered an urban activity, agriculture is an anthropogenic cause of air pollution due to the fact humans partake in agricultural activities that emit air pollutants. Agricultural air pollution mostly includes ammonia, as well as carbon dioxide, methane, nitrogen oxide, and ozone-depleting pollutants, including greenhouse gas emissions. These occur due to equipment used in agriculture that requires the use of fossil fuels, such as tractors and processing equipment.
Air Quality Effects
Low air quality can create several impacts on the environment and society.
Impacts on the Environment
Air pollution can contribute to climate change. This is because the types of air pollution such as greenhouse gases, especially carbon dioxide, methane, and nitrous oxide, can aid in global warming, which ultimately leads to increasing climate change.
Impacts on Society
The main impact of pollution and poor air quality can seriously impact the health and well-being of humans. Vulnerable people, such as young people, elderly people, and people with breathing difficulties such as asthma, are the most likely to be affected by air pollution. However, if the air quality is extremely poor anyone can be impacted. Members of the public can develop respiratory infections and diseases, including asthma, as well as cardiovascular disease and lung cancer or diseases due to bad levels of air quality and pollution.
Air Quality - Key takeaways
- Air quality is how clean or polluted the air we breathe in is.
- AQI or Air Quality Index is an indicator of how polluted the air is.
- The main types of air pollution are particulate matter, lead, ground-level ozone, nitrogen oxide, sulfur oxide, carbon dioxide, and carbon monoxide.
- Factors that cause air pollution include forest fires, volcanic eruptions, transportation, industrial activity, fossil fuels, and agriculture.
- Air quality can impact the environment and society, including the health of humans, leading to breathing difficulties and in extreme cases lung disease.
References
- AirNow 'AQI Basics' https://www.airnow.gov/aqi/aqi-basics/ (No Date).
- EPA 'Carbon Pollution from Transportation' https://www.epa.gov/transportation-air-pollution-and-climate-change/carbon-pollution-transportation (No Date).
- Fig 1: Air Pollution. (https://commons.wikimedia.org/wiki/File:Air_pollution3.jpg), by Janak Bhatta (https://commons.wikimedia.org/wiki/User:Janak_Bhatta), licensed by CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/deed.en).
- Fig 2. Smog in Tokyo (https://upload.wikimedia.org/wikipedia/commons/thumb/d/d1/Smog_in_Tokyo.jpg/1280px-Smog_in_Tokyo.jpg), by Wilhelm Joys Anderson (https://www.flickr.com/people/62019835@N00), licensed by CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0/deed.en).
Learn faster with the 9 flashcards about Air Quality
Sign up for free to gain access to all our flashcards.
Frequently Asked Questions about Air Quality
What are the six levels of air quality?
The six levels of air quality are from the AQI, they are good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy, hazardous.
Do urban areas have more air pollution?
Urban areas often experience higher levels of pollution than rural areas, due to high amounts of transportation, industrial facilities, and fossil fuel.
How does urbanization affect air?
Urbanization affects air by reducing the air quality. Urban areas produce high amounts of air pollution because of the built environment. The heating of buildings, construction, and traffic all release pollution and these are common in urban areas.
What are the symptoms of poor air quality?
Symptoms of poor air quality include impacts on health such as breathing difficulties, asthma, and in more extreme cases lung disease.
What are the 3 main causes of air pollution?
The three main causes of air pollution include transportation, industrial activities, and agriculture.
About StudySmarter
StudySmarter is a globally recognized educational technology company, offering a holistic learning platform designed for students of all ages and educational levels. Our platform provides learning support for a wide range of subjects, including STEM, Social Sciences, and Languages and also helps students to successfully master various tests and exams worldwide, such as GCSE, A Level, SAT, ACT, Abitur, and more. We offer an extensive library of learning materials, including interactive flashcards, comprehensive textbook solutions, and detailed explanations. The cutting-edge technology and tools we provide help students create their own learning materials. StudySmarter’s content is not only expert-verified but also regularly updated to ensure accuracy and relevance.
Learn more