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What’s Going On in This Graph? | World Cities’ Air Pollution

How unhealthy is the air in the world’s major cities?

Note: We will not be hosting a live-moderated “What’s Going On in This Picture?” discussion on Feb. 17.

These graphs show the air quality for twelve major world cities from November 2018 to November 2019. The key for the amount of air pollution uses both the U.S. Environmental Protection Agency’s air quality index and the PM2.5 concentration (airborne particulate matter suspended in air that has a diameter of less than 2.5 micrometers — more than 100 times thinner than a human hair). Much of this pollution is from burning things: coal in power plants, gasoline in vehicles, chemicals in industry, and wildfires.

After looking closely at the graph above (or at this full-size image), answer these four questions:

  • What do you notice?

  • What do you wonder?

  • What impact does this have on you and your community?

  • What’s going on in this graph? Write a catchy headline that captures the graph’s main idea.

The questions are intended to build on one another, so try to answer them in order.

2. Next, join the conversation online by clicking on the comment button and posting in the box. (Teachers of students younger than 13 are welcome to post their students’ responses.)

3. Below the response box, there is an option for students to click on “Email me when my comment is published.” This sends the link to their response which they can share with their teacher.

4. After you have posted, read what others have said, then respond to someone else by posting a comment. Use the “Reply” button to address that student directly.

On Wednesday, Feb. 24, teachers from our collaborator, the American Statistical Association, will facilitate this discussion from 9 a.m. to 2 p.m. Eastern time.

5. By Friday morning, Feb. 26, we will reveal more information about the graph, including a free link to the article that included this graph, at the bottom of this post. We encourage you to post additional comments based on the article, possibly using statistical terms defined in the Stat Nuggets.

UPDATED: FEB. 25, 2021

The Reveal

These graphs appeared in the December 16, 2019 New York Times article “What It Means to Breath the World’s Most Polluted Air: ‘You Can’t Function, You Can’t Thrive.’” The number of deaths from outdoor particulate pollution is staggering: in 2015, 4,200,000 deaths worldwide with 88,000 deaths in the United States. Weakened regulations and a reduction in enforcement have led to an increase in air pollution since 2016, reversing years of decline.

Anything that is burned causes air pollution: coal in power plants, gas in vehicles, chemicals in industry and wildfires. Evidence of wildfires in San Francisco, caused in part by climate change, can be seen in the spike in air pollution in its graph.

Air pollution is linked to asthma and other lung diseases, heart attacks and stroke, as well as developmental problems in children and cognitive impairment in older people. As we saw in the February 10 “What’s Going On In This Graph?” graph on U.S. air pollution, pollution knows no borders. It travels from polluters to the surroundings. It affects young and old, rich and poor. But, pollution does not affect all groups equally. A 2019 study by the National Academy of Sciences found that in the United States, people of color tend to breathe dirtier air than white Americans, despite contributing far less to overall pollution. Why do you think this is the case?

Here are some of the student headlines that capture the stories of these graphs: “Is Your Air Just Air?” by Conner of Iowa, “Air Pollution Poisoning Many Cities From Around the World.” By Ashley of Massachusetts, “Global Air Pollution Trends: Some Cities Breath Easy, While Others Long for a Breath of Fresh Air” by Jacki of Switzerland, “Death in the Air. O, So Much Despair!” by Mia of Washington, “Air Pollution, the Silent Killer” by Tegan of Kimball Union Academy in Meriden, New Hampshire and “What Kind of Air Are You Breathing?” by Genesis of Pennsylvania.

You may want to think critically about these questions:

  • The New York Times Learning Network produced a Lesson of the Day based on a New York Times article “Who Gets to Breathe Clean Air in New Delhi?” From the article and included videos of two children Monu and Aamya who live in New Delhi, you will learn about how air pollution threatens each differently based on their families’ income. You can compare their different levels of air pollution to your level by using the interactive feature of our article “What It Means to Breath the World’s Most Polluted Air: ‘You Can’t Function, You Can’t Thrive.’” What is your reaction to the article and to this comparison?

  • Alexandra Karambelas, a scientist who is affiliated with Columbia University, believes “having access to clean air is kind of a basic human right.” Do you agree? If clean air is a right, how could clean air be provided to all?

  • Go to the article that included these graphs where you can see a video of the movement of worldwide air pollution for the same time period as the graphs. Note the major pollution events, including seasonal events. Which regions are the biggest air polluters? Where does their pollution spread?

  • Berkeley Earth, an independent U.S. non-profit organization focused on environmental data science, provided the data for these graphs. Here you can see the real-time air pollution around the world for all dates in the past two years. Take a tour of the maps and share what you notice and wonder about air pollution worldwide.

The next graph on the relationship smoking and household income will be released by Friday, Feb. 26 with live-moderation on Wednesday, March 3. You can receive the 2020-2021 “What’s Going On In This Graph?” schedule by subscribing here to the Learning Network Friday newsletter. In the meantime, keep noticing and wondering.


Stat Nuggets for “What It Means to Breath the World’s Most Polluted Air: ‘You Can’t Function, You Can’t Thrive.’”

To see the archives of all Stat Nuggets with links to their graphs, go to this index.


A time series graph shows how a numerical (quantitative) variable changes over time.

In the World Cities Air Pollution graphs, the length of the bars represent the numerical variable of daily air pollution for November 2018 through October 2019. Air pollution is measured by the amount of airborne particulate matter that has a diameter of less than 2.5 micrometers per cubic meter. The graphs’ scale shows the correspondence between the amount of particulate matter to the U.S. Environmental Protection Agency air quality index, with a color range from green for good air to red for hazardous and extreme pollution.


The space between each marked value on the scale of a bar graph is called an interval. The length of intervals are chosen based on the range of the values in the data set. Interval lengths on linear scales are equal. Some graphs are constructed using logarithmic scales, which have unequal length intervals.

In the World Cities Air Pollution graphs, the interval length is equal to 25 micrograms per cubic meter). The intervals are marked by parallel horizontal dotted lines.


The graphs for “What’s Going On in This Graph?” are selected in partnership with Sharon Hessney. Ms. Hessney wrote the “reveal” and Stat Nuggets with Roxy Peck, professor emerita, California Polytechnic State University San Luis Obispo, and moderates online with Kevin DeVizia, retired mathematics teacher at Delaware Valley High School in Milford, Pennsylvania.


• See all graphs in this series or a slide show of 60 of our favorite graphs.

• View our archives that link to all past releases, organized by topic, graph type and Stat Nugget.

• Learn more about the “Notice and Wonder” teaching strategy and how and why other teachers are using this feature from our on-demand webinar.

• Sign up for our free weekly Learning Network newsletter so you never miss a graph. Graphs are always released by the Friday before the Wednesday live-moderation to give teachers time to plan ahead.

• Go to the American Statistical Association K-12 website, which includes teacher statistics resources, professional development opportunities, and more.

Students 13 and older in the United States and the United Kingdom, and 16 and older elsewhere, are invited to comment. All comments are moderated by the Learning Network staff, but please keep in mind that once your comment is accepted, it will be made public.

You are watching: World Cities’ Air Pollution – The New York Times. Info created by GBee English Center selection and synthesis along with other related topics.