Search Copying and distributing are prohibited without permission of the publisher
Email a friend
  • To include more than one recipient, please separate each email address with a semi-colon ';', to a maximum of 5

  • By submitting this article to a friend we reserve the right to contact them regarding AMM subscriptions. Please ensure you have their consent before giving us their details.

As concern grows over airborne metal pollutants, the accuracy of data points is being called into question


Public concern over airborne metals and chemicals has been recertified as a hot-button health issue.

The Dallas Morning News ran a 1,200-word story in January on how close to an Exide Technologies lead recycling smelter the state may locate its monitoring equipment for air toxics, a tug-of-war that highlights the mundane headaches required to collect actual data.

But what if there were a secret technique to avoid all of that messy stuff?

Voila! Click on to USA Today's Web site and you will find a fascinating database accompanying a series titled "The Smokestack Effect: Toxic Air and America's Schools." The database provides information on the five worst air pollutants estimated at each of 128,000 schools and the five polluters most responsible for those toxics, along with a good-to-bad nationwide ranking.

According to a first-place award citation in February from the National Institute for Computer-Assisted Reporting, the USA Today reporters "gathered tens of millions of air quality and industrial pollution records" and "then used the Environmental Protection Agency's own pollution model to identify thousands of schools where the air was far more toxic than in nearby neighborhoods."

Unknown is whether there was any discussion at the institute over whether the citation should be lengthened slightly to include inserting the words "likely to be" just ahead of "far more toxic."

As a reality check, the newspaper also sponsored actual air sampling at nearly 100 schools, although there was no systematic way to use those samples to modify the 128,000-school model. The direct measurements showed that the Tennessee school modeled as the worst in the nation received much less contamination than had been projected.

The on-site data showed "levels of manganese thousands of times lower than what the model estimated would be in the air." The nearby manufacturing plant that uses manganese explained that the waste metal ends up embedded in shards of steel that are swept up from the shop floor and discarded. If that information is correct, the material shouldn't have been coded as manganese emitted into the air. Whether it should have been reported to the EPA as manufacturer waste at all is a separate question.

It would be poetic justice for someone to create a scorecard evaluating the newspaper's smokestack project. That's unlikely to happen. The reason is cost.

After the newspaper ran its series, the EPA launched a school air toxics project of its own, taking actual measurements. For a limited period, readings are being taken at 63 sites at a cost of $2.5 million, or about $39,680 per site.

Assuming the unit cost could be halved with greater scope and that a 5-percent sample of schools nationwide would suffice, the cost of evaluating "The Smokestack Effect" would be $127 million. And that's without reimbursing state environmental agencies for the staff time needed to retrieve and replace filters and administer the programs. The EPA's current $2.5-million payout only covers equipment and laboratory analyses.

USA Today's effort is impressive for intellectual elegance in its mingling of sources. The question is how close does the methodology it embraces square with actual measurements and real-world conditions?

Essentially, "the Smokestack Effect" constructs a virtual world from the limited facts available plus an intricate structure of modeled assumptions. "For each square kilometer, the model produces an estimate of which chemicals were in the air, where those chemicals came from and how harmful they might be," said USA Today reporters Blake Morrison and Brad Heath. USA Today's final ingredient was a roster of exact school locations, cobbled together from two dozen or so sources.

A limited reality check for USA Today's modeling will become available within the next year. As it turns out, four of USA Today's 10 worst sites are covered by the EPA measurement program still taking place. One score is already in: the Tennessee school that ought to have had a manganese problem but didn't.

The EPA does an annual Toxics Release Inventory that puts plant-level data into the public domain. The agency also sponsors a software product called Risk-Screening Environmental Indicators, which pulls together risk ratings for each toxic with geographic modeling of air emissions.

Whatever its shortcoming may be, the Risk-Screening software has been evolving since 1991. That allows the developers to respond to feedback, to make changes when users spot shortcomings. The alternative of doing real measurements, aside from being expensive, is subject to Murphy's Law.

The EPA acknowledged recently that an equipment problem messed up readings at 24 of the 63 schools in its current project. It seems the timer that triggers the "off," after 24 hours of "on," was leaking its own chemicals into the filter chamber.

The orthodox solution would be to send the device back to the EPA for repair. However, some state and local agencies, doing the grunt work, chose a low-tech fix: they removed the timer. On two successive days, at the same hour, a staffer went to the problem site. First visit: Turn the gadget on. Second visit: Turn the gadget off and remove the canister.


Have your say
  • All comments are subject to editorial review.
    All fields are compulsory.