The cabbie is late and it's getting dark, the sky turning a dusky, watery pink over the Mexican landscape. It's not a bad place to wait, though: just over a border crossing more vibrant and lively than most, with the gurgling Rio Grande delineating things, its banks weedy and littered with discarded bottles. The bridge at the crossing is broad, with six lanes, including two for pedestrians. A sizable number of tourists mill around, both Mexican and American, crossing to their opposite sides to see what they can't see at home. It'll cost the Mexico-bound a quarter to go south on foot, through a turnstile polished by countless hands, and past an attentively suspicious huddle of Border Patrol, INS, and U.S. Customs agents, and local Brownsville, Texas, law enforcement officers. Once across, they are in Matamoros, a Mexican town more scenic than some along the border, but only just.

Matamoros's main thoroughfare is banked with restaurants, souvenir shops, and discos. Noisy taxis work the street, moving tourists from one diversion to another. Earlier in the day I spoke with one of the taxi drivers, who was hunched over a cigarette on his break. It was meant to seem a casual conversation, but what I hoped was that one of these cabbies might know something about the very active and dangerously esoteric world of Freon smuggling, an illicit trade that claims this bustling border as an epicenter, along with Miami, Los Angeles, Tijuana, and a few Prohibition-era bootlegging towns on the Canada-U.S. line. Like that earlier prohibition, a cash-soaked market was created when something people wanted was outlawed and outlaws found a way to provide it for them. Of course, bootleg Freon lacks the Damon Runyonesque sexiness of bootleg whiskey, but the numbers are impressive: In the three years since the domestic manufacture of chlorofluorocarbons began to be strictly phased out as the result of the worldwide environmental treaty known as the Montreal Protocol, an estimated 60 million pounds of illegal CFCs, with an alarming street value of $1.5 billion, have been sneaked into the country. There have been Freon-related mob activity, Freon-related international incidents, and Freon-related political infighting (most of it involving Vice-President Al Gore). Even Interpol has gotten sucked into the mess, working with the IRS, the EPA, and Customs on an interdiction effort collectively known as Operation Cool Breeze. Recently the CIA and the FBI have hustled in for some sleuthing as well, with the National CFC Enforcement Initiative.

As luck — or maybe simple odds — would have it, among the first Matamorosan I spoke with not only knew about such smuggling, but had a family member involved: his 37-year-old cousin. After much discussion and promises of anonymity, the cabbie agreed to take me to see him. Our assignation was set for seven o'clock.

When the cab appears I climb in beside the driver. He's 40 years old, with thinning black hair, untended sideburns, and an abjectly casual air, all the more so considering the illegality he is about to shuttle me to. With a lurch the taxi heads away from the main drag and down into quieter residential streets dotted with tiny stucco homes kept glowing with whitewash or pastel paint. The cabbie's cousin stands in the open front door of one, his belly overfilling a western shirt that hangs out over leather-belted blue jeans. He seems affable, if a little cautious, and he asks his cousin if he's sure that I won't turn him in. "If he does," the cabbie says, "there's always the river." Using his forefinger, he pantomimes cutting my throat. "We'll throw him in there with all the other bodies." They both laugh.

The cousin leads us into the home, where in the living room a boy of six or seven has fallen asleep on the rug in front of a television beaming out an episode of ER. Indicating the sleeping child, the cousin presses a finger to his lips. "Shhh," he says. "My son played hard today."

As they pass through the kitchen, the two men grab beers from the refrigerator and head for the garage. Inside is the typical suburban detritus: broken bicycles, scattered tools, a doorless deep freeze, a gutted Oldsmobile. But one wall is covered with cardboard boxes stacked three deep and nearly as high as the ceiling — some 40 cases in all. The cousin pulls a carton from the stack, plops it on the hood of the Olds, slices it open, and withdraws a small can of CFC-12 refrigerant, commonly known as R-12 and even more commonly as Freon, which is the specific brand name of DuPont's CFC product.

"Like gold," he announces, displaying the 12-ounce can. "Or diamonds. Costs me a buck for these small ones here, ten or 12 for the fat ones in those boxes." He points to a stack. "But across the border, maybe five, six thousand dollars for all this. A couple loads a month and we'll take a pretty good vacation."

Leaning on the car, the cab driver lights a cigarette. "A vacation in jail," he says to his cousin.

"No way," comes the reply. "Maybe you, not me. You'll kill somebody with that taxi. Turning to me he adds, "Smuggling is not really a problem. We go at night. We know where and when. We use a boat and trucks. That's all I'll tell you."

Once in the United States, he transports the goods to a friend in Houston who pays cash — $30,000 so far. He claims to have made six runs over the past year but plans to schedule them more frequently. "Summer's coming," he says. "The hotter, the better. People pay a lot for a nice, cool breeze on a hot summer day."

Before we leave the garage, he picks up another can of R-12, tosses it up, and catches it as if it were a tennis ball. "It can't hurt nothing," he says. "It's just good business. No big deal." With the blade of his pocketknife he pushes on the sealed opening of the pressurized can. The release of even the tiniest amount of CFC is illegal under the myriad conditions of the Montreal Protocol. But the cabbie's cousin only smiles as the gas hisses invisibly into the night air. "See?" he says. "No problem."

The science of coldness, of chlorofluorocarbons, can be a little daunting. Invented in 1928, R-12 was the coolant used for decades in almost all refrigerators and air conditioners, both for homes and automobiles. But in the mid-1970s, scientists found that the chemical, when loosed into the atmosphere, rises 15 miles above the earth's surface, where it is broken down by the sun. The disintegration releases chlorine, which eats away at the ozone layer that screens out the sun's harmful ultraviolet radiation. Other early research indicated that one pound of R-12 can destroy 70,000 pounds of ozone, a statistic that gains grim meaning if you accept as fact a study done in 1994 by the United Nations Environment Programme, which estimated that every 1 percent decrease in the ozone layer results in at least a 1 percent increase in the incidence of skin cancer. (And, according to the World Meteorological Organisation, for a portion of last winter a decrease of 45 percent was registered in the ozone layer over northern Europe.)

These sobering discoveries led to a push by environmental groups to phase out R-12. Perhaps the most important provision of the 1987 Montreal Protocol, which was ultimately signed by more than 140 countries, was the elimination of almost all CFCs. The protocol made it illegal, as of January 1, 1996, to manufacture R-12 in the United States as well as many other countries, and the importation and use of foreign CFCs was banned in the United States. (A few minor exceptions were made, most notably for very small, controlled quantities used in asthma inhalers.)

The inconveniences that the agreement created were really pretty slight. Many high-technology companies once used CFCs in degreasers and solvents, but the chemicals were simply replaced with less destructive agents. Also easily altered were most of the refrigerators and home air-conditioning systems that used CFCs; in fact, such refitting was essentially complete in the United States by 1993. By far the largest hurdle, however, remains automobiles and their drivers' expectation to be able to operate them in cool comfort. Vehicles made after 1993 use alternative chemicals in their air conditioners, usually the less harmful HFC, or hydrofluorocarbon. But a huge battalion of older, Freon-spitting vehicles still swarms the U.S. countryside, some 80 million of them. Their coolant must be replaced every two to three years, and although it's possible to legally recharge these cars with domestically made CFCs from the nation's dwindling stockpile, which will last two more years, scarcity and federal taxes have plumped up the price. Topping off a car with authorized R-12 cost $20 or so a few years ago; it can run up to $200 today.

It's possible to refit older cars, of course, but such conversion can set an owner back $1,000. Still, the hopeful talk around the negotiating table in Montreal was that people would happily retrofit, because it would eventually become cheaper than paying for expensive recharges. And it likely would have, but for one thing. As Runyon used to say, Enter the smuggler.

Irma Henneberg, a short, frumpy, 51-year-old Fort Lauderdale resident of Panamanian birth, managed for the past several years a number of shipping companies based in south Florida, including one called Caicos Caribbean Lines. From December 1993 to March 1995 the company smuggled 4,000 tons of Russian-made R-12 into the Port of Miami. The street value of the haul was approximately $52 million — an example of just how lucrative the trade has gotten. "The dollar value of intercepted CFCs is second only to the dollar value of intercepted drugs," Thomas A. Watts-FitzGerald, an assistant U.S. attorney in Miami who spearheads the government's effort to police the smuggling, told me. "It's a bigger business than gun-running or the smuggling of prescription drugs."

"MANY OF THESE SMUGGLERS ARE PEOPLE WHO NEVER WOULD CONSIDER BREAKING THE LAW, BUT THE MONEY IS TOO MUCH OF A TEMPTATION," REILS SAYS. ONE FATHER-AND-SON SMUGGLING TEAM WAS NABBED WHILE THEY WERE SLOSHING ACROSS THE RIO GRANDE ON FOOT UNDER CLOAK OF DARKNESS, TWO CASES OF R-12 APIECE TUCKED UNDER THEIR ARMS.

After a highly publicized trial during which she earned begrudging admiration from prosecutors for the sheer height of her rudeness, Henneberg was sentenced to four years and nine months in federal prison, a term she began serving in November 1995. The charges involved the filing of 34 false manifests with the U.S. Customs Service in connection with the R-12. The manifests claimed that the gas would be shipped from Miami to the Netherlands Antilles island of Curaçao, which has a population of only 145,000. At the rate Henneberg said she was shipping, each resident would own about 55 pounds of R-12, enough to cryogenize the entire citizenry.

Henneberg's company was actually doing what virtually all R-12 smugglers do — sell the coolant to U.S. auto-parts stores and various middlemen, who resell it to service stations and air-conditioning repair shops. Such businesses can buy a bootleg 30-pound canister of R-12 for $400. They then charge a customer as much as $80 per pound and pocket the $2,000 difference.

This exploitable margin exists because of a glitch in the environmentalists' plan. A loophole in the Protocol gave developing countries, such as Mexico, until the year 2010 to phase out of the CFC business. And although they are prohibited from manufacturing the chemical here, U.S. companies such as Allied Signal and DuPont continue to pump out R-12 in plants in countries such as India, the Netherlands, and Brazil, for distribution to nations where the CFC ban has not taken effect. (Despite such production, these companies object to the smuggling of their product into the United States and work with and help fund attempts to combat the trade. DuPont is considered by the EPA to be among the strongest proponents of the Protocol, having reversed its original fiercely anti-Protocol stance.)

Even with these efforts — and despite the intentions of the Montreal Protocol — many scientists and environmental organizations have reported dangerously increasing ozone depletion over the last two years. "It's at crisis level," says John Passacantando, the 36-year-old director of the Washington, D.C.-based Ozone Action Group. Passacantando's mien — that of a slightly graying, hypereducated, down-dressing environmental warrior (his desk in Ozone Action's offices is situated beneath a fraying poster of rocker Neil Young) — gives initial camouflage to the group's rapaciousness in going after all things that might harm the ozone. It has staged fierce media attacks on lawmakers who hope to dilute ozone protection laws and has organized successful lawsuits against GE, Whirlpool, Maytag, and others for misleading ozone-related labeling and various Clean Air Act infractions. Recently Passacantando has set his sights on smugglers. The reason: As the National Oceanic and Atmospheric Administration found, last year the holes in the ozone layer opened sooner (in August) and lasted longer (until December) than in any previous year. Equally disconcerting, the 12,000-square-mile holes — about twice the size of Europe — were as large as any on record. According to a report commissioned by Ozone Action and written by Jim Vallette, a respected independent researcher who works out of Southwest Harbor, Maine, "The record event of this past winter was the extremely low values of ozone over Northern Europe. Measurements by British recording stations found levels to be the worst on record." As Passacantando puts it, "We're not just talking about frying penguins anymore."

The thin blue line of Brownsville — in Freon terms, anyway — is a slight, Holly Hunterish, 33-year-old U.S. Customs agent named Sharon Reils, who on a recent morning arrives at work tricked-out in familiar Tex-garb: black, round-toed boots, freshly pressed Wranglers, and a leather-collared cotton shirt. A colleague greets her with a mock bow: "The Ozone Queen has arrived."

Reils was thus tabbed after landing the city's first-ever CFC case last year: One Hipolito Loyde-Guerrero, 42, owner of a down-at-the-heels Houston air-conditioning repair shop, was caught with 60 pounds of R-12 crammed in his car. Loyde-Guerrero made for an underwhelming first case, standing just five and a half feet tall, weighing 165 pounds, and with a history noticeably absent of any previous brushes with the law. "Many of these smugglers are people who never would consider breaking the law, but the money involved is too much of a temptation," Reils says. Brownsville-based border police nabbed one father-and-son smuggling team while they were sloshing across the Rio Grande on foot under cloak of darkness, two cases of R-12 apiece tucked under their arms. When they stumbled into the authorities' bright search beams they simply stopped wading and surrendered.

Despite the presence of some very unsavory types within the R-12 netherworld — the Russian mob, for instance, is a significant player in the worldwide R-12 trade — Reils's criminals tend to be small-timers and their apprehension not nearly as flashy as those in, say, Florida, where R-12 arrests by the undercover agents of Operation Cool Breeze can assume a Miami Vice-like Sonny-and-Rico-gonna-bust-some-heads feel. "Our arrests aren't the kind where we wear ninja suits and kick in doors," Reils explained as she tucked herself into her five-by-five-foot cubicle situated in a windowless corner of Brownsville's Customs office. "More likely, we work with informants, study bills of lading, and track sellers and buyers. Arrests are made quietly; some of the people who are caught seem genuinely surprised that we're making such a big deal out of this."

Criminals aren't the only ones expressing disbelief at the large and concerted CFC intervention effort — many politicians are, too, despite actions by Vice-President Al Gore and Attorney General Janet Reno to keep the program politically viable. The policing effort achieved its highest profile last January, when shortly after 5,000 tons of illegal R-12 were intercepted in Miami, Reno staged a press conference. "To CFC smugglers, we say: We will find you, we will shut down this black market, and we will not let you endanger our ecosystem and our children for a few dollars," she declared. Such displays — as well as Gore's continual invocation of the depleting ozone in his book Earth in the Balance, in talks with environmental groups, and in funding forays on Capitol Hill — have made this particular environmental cause one of the most acted upon green initiatives yet. The effort, and particularly the provisions of the Montreal Protocol, remains very controversial, however. Nevada's legislature is currently considering a bill that would attempt to override the Protocol and legalize production, sale, and use of R-12. The Arizona house passed a similar bill in 1995. Both bills are little more than symbolic, however, since neither the Clean Air Act nor international treaties can be set aside by the states. "Clearly, a small group of legislators was trying to make a point," says John MacDonald, director of government affairs in the Arizona attorney general's office. "And no, Arizona will not begin producing CFCs — that's a ridiculous notion."

WHEN THE HARM THAT CFCS ARE CAUSING IS SO TECHNICAL AND ABSTRACT, AND WHEN THE BENEFIT THEY PROVIDE IS SO BLANDLY AND SELFISHLY APPEALING, IT ISN'T ALWAYS EASY TO MAKE THE APPROPRIATE PEOPLE FEEL OUTRAGED. MIDWAY THROUGH ONE RECENT SMUGGLING TRIAL, THE JUDGE ASKED, "SO WHAT AM I SUPPOSED TO DO IF MY AIR CONDITIONER BREAKS DOWN?"

Even so, such political maneuvering unsettled Ozone Action's Passacantando enough that he fired off an anxiously aggrieved letter to Nevada's legislators. "If A.B. 163 were to become Nevada law, it would undermine years of international negotiations," he wrote. "Furthermore, production of CFCs in Nevada would make it a rogue state exporting a highly destructive product for short-term gain, not unlike Columbia's [sic] role in exporting cocaine." The letter did not find a generally receptive audience. "Anything that will undermine international negotiations in the area is OK with me," replied one legislator. "I believe the ozone scare is just a scare, with no scientific data."

As it happens, the suspected speciousness of ozone science is a common topic in Washington, perpetually debated by a familiar list of critics and quasi experts. In 1995, Representative Tom DeLay, a Texas Republican and the majority whip, joined Representative John Doolittle, a California Republican, in a failed attempt to withdraw the United States from the Montreal Protocol, and he continues to pooh-pooh the effect that CFCs have on the ozone. "The current hysteria is due more to media hype and unsound science that just doesn't add up," says John Feehery, DeLay's press secretary. Fred Singer, DeLay's science consultant and a founder of the proudly partisan Science and Environmental Policy Project, has suggested that CFCs have very little effect on the ozone level and that fluctuations are natural and the result of natural factors, like erupting volcanoes. Singer, however, admits that he hasn't conducted any actual research since the mid-1970s.

Perhaps the most often cited contrarian source is Sallie Baliunas's 1994 article, presented at the West Coast Roundtable for Science and Public Policy, "Ozone and Global Warming: Are the Problems Real?" Baliunas, a staff astrophysicist at the Harvard-Smithsonian Center for Astrophysics, has written that "there is currently no evidence to suggest that man-made chemicals, like CFCs, have significantly eroded the ozone over most of the world.... Rather than supporting federal regulation, scientific evidence leads to the conclusion that regulation is both economically devastating and scientifically irresponsible. Federal regulation...will cost the U.S. economy an estimated $2 trillion in the near term." Baliunas's figures are contested by environmentalists and other scientists, however, such as University of California-Irvine chemist Sherwood Rowland, who won a Nobel Prize in 1995 for discovering the connection between CFCs and the deteriorating ozone layer. The issue, says the 70-year old scientist, can't be reduced quite as neatly as Baliunas's dollars-and-cents equation renders it. "What," Rowland asks, "is the price tag on the future?"

Sharon reils parks her bright green Jeep Cherokee near the Gateway Bridge, one of three crossings from Brownsville into Mexico. We stand for a moment under the hot sun and watch as blue-suited customs agents do their efficient work, stopping and searching cars coming in from Mexico, casually evicting their occupants while other agents clamber inside for a more thorough search. A young couple, most likely runaway teenagers, is led to a waiting patrol car. An agent pokes around a load of textiles in the trunk of another car while the driver's baby wails from the backseat.

Reils heads over to the nearby clearing area to which all truck traffic is diverted. It's a football-field-size concrete slab lined with loading docks; forklifts hum about, lugging pallets spilling over with every item imaginable, from gunnysacks of seashells to boxes of Nike running shorts. After taking in the scene for a moment, Reils heads over to chat with Border Patrol Inspector Jesse Trevi˜o, a stocky man in his thirties with a close-cropped mat of black hair.

"Anything interesting happening?" Reils asks.

"Nothing much," says Trevi˜o. "It's pretty quiet. We had a circus that was on its way to Mexico with 14 white tigers. They had papers for the tigers, but the FDA was concerned about the 3,000 pounds of meat they had to feed them."

While the search for illegal drugs and contraband is workaday routine here, the relatively new R-12 trade has introduced some unique obstacles. Inspectors check documents and often search loads, but as Trevi˜o points out, "It's impossible to check every truck for Freon." Trained dogs, used to sniff out drugs, are useless when it comes to cans of CFCs. And even if suspect canisters are found, it isn't always easy to make the case for smuggling, since some loads of R-12 are ostensibly legal and simply passing through the United States on their way to somewhere else.

Thus Reils, with her vigilant interdiction effort, has to rely on sting operations and the enlisted help of several government agencies, including the IRS (illegal R-12 shipments reportedly cost the federal government more than $100 million a year in lost excise taxes and customs duties) and the EPA. And many of the larger-scale seizures have been accomplished not through these concerted efforts — or with high-tech gadgets such as massive, warehouse-size X-ray systems — but rather with the most time-honored of methods: One smuggler finks on another.

I wanted to get a little better sense of the sweep of Freon smuggling, so a few days after I left Matamoros, I spent some time with accounts of all the U.S. arrests from the past few years. Sitting in my office, with the windows wide open and the cool and damp northern California breeze drifting in, I monitored the ever-expanding black-market world of R-12. Charges have been filed by U.S. attorney's offices in San Diego, Los Angeles, Houston, Miami, and Savannah, Georgia. In Los Angeles, Dennis O'Meara, a 50-year-old owner of a refrigerator reclamation company, is on trial this month for sneaking more than 45 tons of CFCs into the United States through the Port of Los Angeles. In Georgia, 43-year-old Johnny Willis Simpson was nabbed with 250,000 pounds of CFCs; he was bribing border officials at the rate of $50,000 per load to get the gas into the country. In January 1995, two Floridians, who claimed to be professional wrestling promoters, were caught importing 126 tons of R-12, worth $2.5 million, from a port in southern England. Another Florida man tried to buy, with $115,000 cash, 500 30-pound cylinders of CFCs. Back in Brownsville, police have tracked illegal shipments of R-12 — like those couriered by my Matamorosan cabbie's cousin — to warehouses owned by car-parts distributors.

The stretch of the Texas border Reils patrols has inherited a larger share of the trade of late, mostly because of the success of a crackdown in Florida, where the bulk of illegal R-12 has been seized so far. Assistant U.S. attorney Tom Watts-FitzGerald, who coordinates Operation Cool Breeze, has convicted 19 smugglers, the biggest of whom have been sentenced to up to 57 months. There have been millions of dollars in fines. Since late 1994, government agents have targeted dozens of companies for investigation and impounded tons of CFCs. A batch of cases is currently being brought to trial, including ones based on a dozen indictments announced last January by the Justice Department.

Such showy arrests were considered major successes, but officials admit that it's impossible to measure the impact of the government's efforts to stop the smuggling. More than ten cargo ships arrive at the Port of Miami every day, bringing in or picking up 24,000 cargo containers. Along the Texas border, another 12,500 containers are moved each day by truck and train.

And even if the smuggler is unlucky, the literally ethereal nature of R-12 may come back to help him in court. When what you are smuggling can't be seen, when the harm it is doing is both technical and abstract, and when the service it provides is so blandly and selfishly appealing, it isn't always easy to make the appropriate people feel outraged. As one Texas judge asked in the middle of the trial of a smuggler Reils busted, "So what am I supposed to do if my air conditioner breaks down?"

The cabbie has returned me to the border, and his cousin is presumably back at his labors, readying his loads of R-12 for the midnight sneak into Texas. Earlier Reils drove me north of the border to a nondescript eight-story structure — a home for retirees, the tallest building in Brownsville. "That's where the Border Patrol has their lookout," she said, motioning down to the Rio Grande. "From there they can spot for suspicious crossings — smugglers or illegal aliens." Today the border appears quiet — a calm before the storm, Reils says. "By the middle of this summer, the legal sources for Freon will be pretty much dried up around here. We expect it to come pouring in then. Though they have to get past us first."

I left her there, on alert, and headed for home, where the weather had turned unseasonably warm. I rolled up the windows and snapped on my car's air-conditioning, enjoying the immediately frigid air that blasted out. Though my Honda is pretty new and doesn't use R-12, I still wanted to investigate the final stop for the gas, and I pulled off the freeway and drove along a road spotted with gas stations. At random I picked a three-car garage abutting what must have been an ersatz zoo, or maybe the holding pen for an ostrich rancher. Several of the birds stood at the fence, watching me, while a few dozen chickens danced at their feet. The mechanic slid out from under a Chevy.

"I need to get my AC recharged," I said. "How much will that be?"

"Probably about $175 or so," he said. "Depends if it's leaking, though."

"Why's that?"

"'Cause they're trying to outlaw R-12 because it's bad for the environment." He'd gotten to his feet now, a tall, balding man in blue coveralls.

"Can I get it cheaper somewhere? I heard I can buy Mexican R-12, or some bootleg stuff."
He looked at me a long moment. "I don't know anything about that. All I know is that I'm not getting it cheap. That canister over there cost me 600 bucks. Sometimes the price goes up three times in one day. From me, though, it's $175."

Though many garage owners wouldn't let a customer, never mind a stranger, poke around their shops, my recent introduction to the world of smuggled Freon made me suspicious, and I wondered if the illegal gas is so prevalent that I'd stumbled into some so easily. Reils had mentioned that the only way to know if you are buying legal R-12 is to check the cans the mechanics use; domestically produced gas, which would have been manufactured before January 1, 1996, is the only legal type and is distinguished by a date stamping and markings in English. I started to head over to where the mechanic had filled the larger canister, looking for signs of contraband R-12.

"Hey!" the mechanic shouted. "I can't have you over there."

I retreated to the entrance, looked the place over one more time, and started for my car. "Thanks," I yelled. "I might be back."

"You will if it gets hot enough," he said, and slipped back under his car.