Part of a motor vehicle’s exhaust system, a catalytic converter, seen here being removed from a motor vehicle, transforms noxious gasses produced by internal combustion engines into harmless carbon dioxide and water vapor.

A sharp increase in catalytic converter thefts prompted Houston’s City Council Wednesday to ban the sale of used or “cut” emissions-control devices.

The ordinance makes it illegal to possess catalytic converters that have been cut apart to extract the valuable metals from the devices that remove pollutants from car exhaust. The converters, part of a car’s exhaust system located near the muffler, are required by law to be installed in most vehicles to control pollution.

EXPLAINER: What to know about soaring catalytic converter thefts as Houston bans some sales

The ordinance applies to catalytic converters that have been cut apart or cut off a vehicle, rather than unbolted, and does not criminalize the sale of new parts or those carried out by city’s roughly 100 registered metal recycling facilities.

Mayor Sylvester Turner said Wednesday his administration is doing "everything we can think of" to make it harder for thieves to steal and resell catalytic converters in Houston.

The thefts have surged in recent years due to supply shortages and increased global demand for cleaner cars. Houston police recorded a five-fold increase in theft cases since 2019, with 2022 on track for a record-breaking year at 3,200 thefts so far.

"If you are going to do it, we are going to make it as inconvenient as possible for you," Turner said.

The Houston Police Department has said its officers recover about 100 catalytic converters a day. Without the authority to seize stashes for investigation, however, police cannot make arrests or link suspected stolen parts to specific vehicles and victims.

By creating a new Class C misdemeanor criminalizing the possession of the cut parts, the ordinance will make it easier for police to file charges against a person with catalytic converters that have been cut, a tell-tale sign of theft, officials said. Legitimate mechanics unbolt the part when uninstalling it, making stolen ones — typically cut off by thieves who crawl under vehicles at night — easy to spot.

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Under the ordinance, suspected thieves will face a separate charge for each catalytic converter found in their possession.

Roy Narvaez, owner of Street Performance and Offroad, said he first noticed the uptick in catalytic converter thefts at the outset of the pandemic in early 2020. Thieves especially seemed to target Toyota trucks, a preference Narvaez attributed to the “super exposed” placement of the part on the trucks’ undercarriage.

The trio of metals contained in catalytic converters — platinum, rhodium and palladium — have seen historic price increases in recent years as automobile companies strive to meet tougher emissions standards. The price of rhodium alone has skyrocketed by more than 2,000% in the last five years.

“It was as if there were diamonds inside the catalytic converters,” Narvaez said. “People were acting like that.”

At first Narvaez could do nothing to help his customers, who often had to pay thousands of dollars and wait months for replacement catalytic converters. Then he had an idea.

The mechanic designed a simple metal plate that could be welded or screwed onto the trucks’ undercarriages to deter thieves. After prototyping several designs, Narvaez and his staff began bulk producing the steel shields, known as skid plates for their resemblance to protection devices frequently installed on off-road vehicles. He estimates he installs one or two daily.

Narvaez charges about $550 for each specialized skid plate. Customers often balk at the cost, he said.

“They go, ‘Oh no, no, no,’” he said. “Unfortunately, because of the crime, you have to make a decision: do I gamble that it is not going to happen to me?”

WATCH: What is a catalytic converter? Here's why people steal them and how to help stop the theft.

Most of Narvaez’s customers choose the precautionary shield when faced with the prospect of waiting for a replacement part. Across the United States, catalytic converters are back-ordered up to six months due to high demand, with some manufacturers running lengthy wait lists.

Ultimately, he said, “Why not pay $500 out of pocket and have a little peace of mind?”

Narvaez supported the ordinance Wednesday, but said it may not be the crime deterrent council members hope it will be.

"At the end of the day, I know thieves don't care about laws," he said.

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Nora Mishanec is a Hearst fellow for the Houston Chronicle.

She previously worked on the breaking news team at The San Francisco Chronicle, and as a reporter at The Register-Star, the nation's second-oldest newspaper.