In the wake of a study that found San Jose’s Reid-Hillview Airport exposes children to high levels of lead, Santa Clara County is doing further testing at the site and the county-owned airport in San Martin to understand the extent of contamination.

While the most recent study in August investigated blood lead levels of those living in the surrounding area of Reid-Hillview, the new round of testing will look into how contaminated the soil is at each airport to determine whether the ground needs to be dug up and replaced with new earth.

The results of the new testing — which are expected to be released March of next year — are bound to add fuel to the ongoing debate surrounding the future of Reid-Hillview.

County executive Jeff Smith said that he’s concerned that what the airborne lead study found may also be showing up in the area’s soil.

“We’ve got a piece of property (and) we have reason to believe that there may be contamination,” said Smith. “We need to figure out if there’s something we need to do about it. If the levels are minimal, that’s pretty much the end of it. If they are high, we need to dig up surface soil and replace it with non-contaminated soil. We need to see what our baseline is.”

The August lead study offered further evidence for county officials and nearby residents who have long advocated for the closure of the airport and its relocation 23 miles southeast to San Martin, citing health and noise concerns, as well as a need for more housing in a region already short of potential development sites.

But flight school owners and pilots at Reid-Hillview and San Martin residents claim that the August study did not account for other potential factors that revealed high levels of lead, and say that relocating the San Jose airport would put a strain on the much smaller one in San Martin. The best solution, they argue, is to switch all planes at Reid-Hillview to unleaded fuel, a county-led initiative that will start this coming January.

When Reid-Hillview Airport was established in 1939, the surrounding area was mostly agricultural. But since then, thousands of homes and two schools have popped up in the area. The county has owned the airport since 1961 and approximately 52,000 people live nearby.

Efforts to shutter Reid-Hillview started in 2018, when county supervisors voted to end federal grants for the airport, allowing for its closure by 2031. The August airborne lead study was then commissioned by county supervisors two years later.

The study analyzed 17,000 blood samples between 2011 and 2020 from children under the age of 18 and found that those who lived within half a mile of Reid-Hillview had elevated levels of lead compared to those who lived farther away, a difference of about .40 micrograms per deciliter, or one-tenth of a liter. Health experts say lead can cause damage to children’s brains and nervous systems and trigger learning and development issues.

The August study’s results were championed by District 2 Supervisor Cindy Chavez, who originally asked for the testing and whose district includes the airport.

“We have an obligation to make sure that we understand the implications of the airborne lead as a contaminant,” said Chavez. “To me, the more information that we have, the more information we can share, the better we are able to respond to the contaminate. That’s why we’re taking this action.”

Santa Clara County’s Roads and Airports Department Director Harry Freitas said that if either sites are going to have any other uses aside from an airport, then knowing what is in the soil is important.

“Our purpose is: ‘What to do with the land if we need to clean it up?’ said Freitas. “If you were going to buy some land or sell some land, you’d want to know what’s on the land. We really want to get an understanding of what we own. What’s in the dirt.”

But John Carr, a member of the Santa Clara County Airports Commission who has been critical of the proposal to close Reid-Hillview, said he thinks the county is conducting a study for something that is already known.

Carr and others who want the airport to stay open argue that legacy lead from old paint in the area’s homes is causing the elevated levels, as well as existing contamination from a racetrack that was once in the area. (The August study did attempt to take into account lead-based paint levels in the blood samples.)

“It’s just so misleading and disingenuous,” said Carr about the new study. “They didn’t get the hoorah for closure that they wanted based on this latest (August) lead study. They’re doubling down on a feckless argument to fuel the fear factor.”

But Freitas shrugged off any suggestions that there is any ulterior motive to the new study.

“A lot of people are trying to make a big deal out of a lot of things,” he said. “We’re always concerned about what’s in the dirt. It’s a super sensitive issue.”