The federal government banned lead paint in 1978 because of the health threat it posed to children in particular, but KPNX wanted to show Phoenix residents where the threat is today. Wes Williams, who attended the NICAR Bootcamp in January, tells how the series, which was begun in January, unfolded.

We tested playground equipment and city parks and schools across the area and found many contained chipping lead paint. Our I-team reporter, Lonni Leavitt, gave me a list from the state showing the number of homes built in each decade for every Census tract in our county. We wanted to be able to tell people whether they lived in an area full of mostly older homes (built before 1978), which therefore might contain lead paint.

First problem

Our problem was that no one knows in which Census tract they live, so we decided to convert this to ZIP codes. I found a table on the Internet to convert them through one of the groups that works with the Census bureaus, but I found there was a problem with some Census tracts covering more than one ZIP code, and vice versa.

Fortunately, there proved to be an easier solution. I went to the Census Bureau home page (http://www.Census.gov) and found the Summary Tape File 3B search tool under the Data Access Tools/Lookup section. The STF3B classifies the 1990 Census data by ZIP code. I found a list of ZIP codes for our area at the U.S. Postal Service home page (http://www.usps.gov) and plugged them into the STF3B search tool.

The STF3B gives an extended list of categories. One of them happened to be "year dwelling built." I also had it give me the total number of homes for each ZIP code. I ended up with a text file of the total numbers of homes built in each decade by ZIP code.

It was easy to save this, parse it into Excel, and start crunching numbers. I figured out which ZIP codes had the highest percentage of older homes, and we did a story on where those "danger zones" are (areas where at least 80 percent of the homes in each ZIP code were built before 1990).

Of course, so far, this sounds like a newspaper story, not one for broadcast. But we checked out homes and schools in those areas, found higher lead in both, and used the "danger zones" for a graphic in the story. We then included the full table with other lead paint information in a brochure we printed for our viewers.

We were surprised by some of the results. We expected the downtown areas to show up at the top of our list, but we didn't think about Sun City, where almost all of the homes were built back when lead paint was in use, and the two local Air Force bases, one of which has been turned over for civilian use. We included since people still work in those same buildings.

Troubleshooting

I should have looked for another source of the data by ZIP code first rather than trying to convert it from the Census tract list the state gave us. Because the Census data worked by decades, I could only determine how many homes were built before 1980, not before 1978, when lead paint was banned. Three of our current ZIP codes did not appear in the Census data because they didn't exist in 1990. They're in newly-developed areas, but we had to catch that they were missing to put them on our list. We listed them as 0 percent. Some ZIP codes I got from the Postal Service home page belonged to just mail boxes, so they did not show up in the Census data. We didn't include those in any of our work. It wasn't really a problem, but I didn't start my "lab notebook" detailing every step of work until my next project. I realize now just how much that might help me in the future. Take the time to jot a quick note. It will save you a lot of time later. It's already saved me a couple of times in the past month.

Wes Williams can be reached at (602) 261-6152, or send e-mail news@indirect.com