Air Quality Index

Pollution is becoming more and more of a problem for people all around the world, and understanding the ways that scientists study pollution is more important than ever. This activity will teach students how scientists measure and assess the quality of air in a city and share that information with the general public. This activity is based on a great guide by The University of Northern Iowa (check out the link for a great worksheet to hand out).

Grades: 6-8

Background

The Air Quality Index is a measurement of pollutants present in the atmosphere within a specific location. The AQI measures different pollutants on a scale of 0-500 and the impact of air quality on different groups of people. Each category within this scale indicates the risks present to people living in that area. You can often find an AQI report  on weather websites or mobile apps that indicate the quality of air in your local area.

Capture

The EPA measures five different major pollutants common in the atmosphere: ground-level ozone, particle pollution (particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. In order to calculate the air quality index within a location, scientists measure a pollutant concentration over time in an averaging period. These averages are calculated to a range that is represented in the AQI table above. It is important to note that pollutant amounts vary across regions, so different countries have their own standard amounts of each pollutant.

Reading the AQI report for your local area is an important habit to maintain, especially if you are considered a part of “sensitive groups”. Sensitive groups are those with respiratory conditions like asthma, lung disease, heart disease. Children, the elderly, sick people, and pregnant people are also considered sensitive groups in the AQI. These groups should limit or avoid outdoor activity when local AQI is 101 or higher.

What You’ll Need

To complete this activity with your students, you will need to print out these packets by the University of Northern Iowa. This link provides teacher directions for the activity, so students will only need pages 5-15. If you would like a shorter activity, I recommend using pages 5-11. Below I will provide a guide to each activity and a description of the activities that are included in the worksheet.

Activity Guide

There are four major activities included in this worksheet, and I will describe each one here. I encourage you to read through the worksheet first before reading this next section.

The first activity on page 8 serves as a way to elicit students’ prior knowledge of air quality and pollution. Before completing this page of the packet, students should be introduced to the basics of AQI and how the scale works. These questions will provide important context for the activity and they are a useful way to set up the activity.

The second activity on page 9 guides students as they learn a basic way to calculate the AQI. It is important to note that the equation provided in this activity is not the exact way that scientists measure and calculate AQI, but it is a helpful way for students to understand the processes involved in calculating the AQI. I want to note that it was somewhat difficult for me to understand the equation at first, but I will provide important context information you need in order to calculate this problem. Here is how the worksheet instructs you to calculate the AQI:

“The Air Quality Index (AQI) is actually the percent of the NAAQS standard that is present in the atmosphere. To figure your percent on a test you take your score and divide by the amount possible then multiply by 100. You follow the same procedure when calculating the Air Quality Index. Take the amount of the pollutant in the atmosphere and divide by the NAAQS standard for that pollutant then multiply by 100. This number is the air quality index number. The Air Quality Index for a certain location is given by examining the percentages for the 6 criteria pollutants and selecting the highest one.”

This procedure confused me at first, but after doing some digging on the AQI website I figured out what they were saying. The first step is to refer to the NAAQS page in order to access the standard amount for each pollutant. Refer to the “level” table for each pollutant in order to get the standard amount for each pollutant listed. For the pollutants with more than one averaging time, refer to the shorter time listed. Once you have your standard amount, then you can refer to the equation provided below:

Air Quality Index = Pollutant Amount / Standard Amount x 100

For example, let’s calculate one of the problems listed on page 9. In Chicago the level of carbon monoxide is 12 ppm. To calculate the AQI, refer to the NAAQS table. The standard amount of carbon monoxide is 9 ppm. Let’s put that into an equation:

AQI = 12 / 9 x 100, AQI = 133.

Now, refer to the AQI color coded table. 133 falls under the orange “unhealthy for sensitive groups” category, so those groups should limit or avoid outdoor activity. We can repeat this process for the other pollutants recognized by the AQI.

I have implemented this activity with 6-8th graders, and I can tell you from experience that you should guide them slowly through this equation. It is helpful to do a problem together as a class and guide them to solve the equation with other examples. My students enjoyed finding the AQI for their own cities once they got the hang of solving the equation.

The third activity on pages 10-12 involves creating a broadcast in order to communicate the air quality index to local communities affected by the amount of air pollution that day. This activity provides a great way to allow students to be creative with their forecast.

The fourth activity on pages 13-15 can serve as an evaluation activity to get students to demonstrate what they learned from the activity. It guides them as they go through the entire process of calculating and broadcasting AQI information for a city on a particular day. It’s a nice wrap up that reinforces what they learned throughout the activity.

Discussion

There are many ways you can incorporate a discussion before or after completing this activity. Here I will include some discussion questions you can pose to your students:

What are some major sources of air pollution? How can we minimize the impact of air pollution? What impact does air pollution have on environments? What impact does it have on people?

NGSS Standards

Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment.*

ESS3.C: Human Impacts on Earth Systems

  • Human activities have significantly altered the biosphere, sometimes damaging or destroying natural habitats and causing the extinction of other species. But changes to Earth’s environments can have different impacts (negative and positive) for different living things.
  • Typically as human populations and per-capita consumption of natural resources increase, so do the negative impacts on Earth unless the activities and technologies involved are engineered otherwise.
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