Houston total cancer risk per million by census tract as determined by the 2005 National-Scale Air Toxics Assessment (NATA). Source: epa.gov.

What's your cancer risk in Houston? (Bigger than in Dallas)

The above map shows cancer risk by census tract in the Houston region using data from the Environmental Protection Agency. We used the same data to emboss the cover of Cite 93. As in other cities, the areas closer to the center of Houston have a higher risk for cancer. However, one needs only to compare screenshots from the epa.gov mapping tool to see that Houston is exceptional. Let’s look at Dallas-Fort Worth versus Houston.

Dallas-Fort Worth cancer risk.

The I-35 corridor from I-635 to downtown Dallas has a high cancer risk of 75-150 per million.

Before looking at more data, let’s ask what exactly “cancer risk” means. The data for these maps comes from the 2005 National-Scale Air Toxics Assessment (NATA), and you can read the glossary of terms here. In short, the numbers represent the risk beyond what a person not exposed to the measured toxins would have. This is the total risk for developing any type of cancer over a lifetime.

Back to our comparison: the area in Dallas is smaller than the area with the same risk in Houston.

Houston cancer risk.


Houston has a large area of cancer risk at the 75-150 per million range on the east side of town near the Ship Channel. That high-risk blob extends its tentacles along freeways to the west. Let’s zoom in.

Houston 610 Loop-area cancer risk.



How do we interpret these maps? Why does Houston have such large areas of heightened cancer risk? You can learn more by reading Larry Soward’s contribution to the current issue of Cite (93), “Growing Risks: Challenges to Maintaining Houston’s Prosperity and Air Quality.” Though this map does not pinpoint specific causes, it does give an overall idea of risk. The presence of the industrial complex on the east side appears to have a major effect.

Should you specificially be worried? After all, “75-150 per million” comes out to a small fraction — 0.00015 or about one out of every 7,000 people. Furthermore, according to Dr. Elena Craft of the Environmental Defense Fund, total cancer risk is associated with a wide range of factors including family history, socioeconomic status, lifestyle, age, and exposure to pollution. Nonetheless, any heightened risk is scary, and I want to know whether my young and economically comfortable friends on the east side are at a great risk of developing cancer specifically because of where they live. And there are other health problems caused by air toxins besides cancer. My concern for my friends on the east side is outweighed only by my concern for myself and my own family.

Detail of cancer risk along the Southwest Freeway.



What many people I’ve spoken to about this map find striking are the tentacles of high risk that reach well into affluent southwest neighborhoods, including Southampton and Boulevard Oaks. The map above shows that the 75-150 per million range includes the area between the Southwest Freeway and Bissonnet. Think of the oak canopy along South Boulevard. Think Poe Elementary School. The high-risk area also includes the Museum District and Hermann Park. I lived just outside this area for 12 years. A large number of Rice Design Alliance members and Cite subscribers live in the general area as well. It appears we are all in this together, rich and poor, east and west.

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    12 Comments

    1. 1

      I’ve been playing with these maps a little an trying to understand them. But isn’t the southwest part fairly obvious?

      There is a known “danger zone” around highways and major roads (such as Westheimer or Kirby) where cancer risk skyrockets for school children if they aren’t protected from the air.

      Isn’t the little arm heading southwest simply the area that is the highest trafficked and most often congested freeway in the region along 59 and the 610 bottlenecks?



    2. 3

      [...] Rice Design Alliance used data from the Environmental Protection Agency to create a map of the areas in Houston with higher risks of developing cancer.  The neighborhoods closer to the Ship Channel [...]


    3. 4

      Jay, I agree with your point that the southwest risk is obviously connected with the most congested freeways. That was the conclusion I tried to point readers to by focusing on those “tentacles along freeways.” In retrospect, now that this post has been picked up by other media outlets, I could have been more explicit making that point throughout the blog post. Though the blob on the east end is huge, my intent was to show our shared risk…and, ultimately, the need for a regional solution.


    4. 5

      [...] Offcite looks at your cancer risk in Houston. [...]


    5. 6

      Is there anywhere one could find a copy of the 610 Loop map with streets identified? It looks to me like, looking at the near northside area, there is a north-south line bounded on the east by 59 and on the west by Hardy that is an area of the most serious cancer risk. But am I reading it right, or does the area extend further to the west? And along what road does the dark blue cross east-west across Northside Village?


    6. 7

      Carol, Yes, I think you’re reading it right. The areas of highest risk tend to hew closely to the freeways: In the Near Northside, that means I-45, 1-10, and the Eastex Freeway. It appears that there is also an area of highest risk moving northeast along Liberty Road through the Fifth Ward.

      Unfortunately, the limits of our formatting make it difficult to provide a more legible map. But you can access this information yourself:

      1. Navigate to epa.gov.
      2. Scroll down and find the “MyEnvironment” search box on the left-hand side and enter your ZIP.
      3. On the next page, you will see a horizontal menu of icons. Click on the one that looks like a large asterisk, labeled “MyHealth.”
      4. That will bring up a map of Houston. In the upper right-hand corner of that map, you will see a box labeled “Map Contents” that allows you to toggle between views of cancer risk, infant mortality rate, low birth weight, etc.

      That should allow you to use the map according to your own needs! Hope this helps!


    7. 8

      [...] Offcite looks at your cancer risk in Houston. [...]


    8. 9

      My concern here – and I’m surprise that EPA is so cavalier about this – is that the places with the highest risk seem to correlate to the most walkable, densest places with the best transit service. I can guarantee you we are now going to hear from our sprawl-loving friends that it’s much safer to live in sprawl than in urbanism. If I say that it appears that the reason this map looks like this is all the highways and cars, the answer doesn’t change: it’s healthier to live in sprawl than in urbanism. That’s a pretty big problem, if it’s true, although all previous health reports point to the opposite.


    9. 10

      David, I appreciate your comment. This map is based on measured air toxins. I think our response should be to reduce air toxins so the walkable places we love do not have projected high cancer risks. People who live away from highways but who are heavy users of highways put an unequal environmental and health burden on those who do live near highways. People who consume petrochemicals and fuel (everyone!) put an unfair burden on those who live near the oil and gas industrial areas.

      Low income, Latino, and African American communities have dealt with this type of injustice for a long time. Air pollution in Houston, however, is an environmental justice issue that encompasses wealthy, majority White neighborhoods as well. If the old wealth and the new wealth moving into Houston’s core is threatened, that could be a good thing if the responses benefit everyone.


    10. 11

      Raj, you’re exploring something that has never had any legs, so to speak, but maybe a time has come or is coming. The idea that people should pay a fee for the damage they do to others is pretty interesting. Could begin by simply taxing vehicle emissions. Every vehicle gets tested every year already, so how hard would it be to apply a fee that you pay at the time of inspection? The money would be directed to individuals in the risky areas and to support forms of transportation and lifestyle that are very low emissions.

      I’d like to show you a map. How do you do that in this blog?


    11. 12

      [...] Offcite looks at your cancer risk in Houston. [...]