ON horseback or in pale green Suburban trucks, the United States Border Patrol has clamped down on illegal immigration in this desert metropolis of 700,000.
Authorities are powerless, though, to stop another unwanted flow: air pollution from the sputtering cars, dirt roads, and home-grown industries of Juarez. That Mexican city of 1.5 million and El Paso, Texas, interlock like puzzle pieces, separated only by the Rio Grande.
Citizens of this essentially single, bi-national community have not waited for Washington and Mexico City to solve the air-quality problem. Instead, they have initiated action. ''The regulatory community wasn't going to clean up our air,'' says Danny Vickers, an El Paso businessman who chairs the Paso del Norte Air Quality Task Force.''The community has got to stand up and say, 'We're behind you.' It's a matter of survival.''
Scrubbing smog-filled skies
Mr. Vickers's bi-national task force is composed of businessmen, educators, environmentalists, local officials, and local representatives of state and federal regulatory agencies. Formed in 1993, it has launched pollution-reduction projects to scrub the smog-filled skies that now rest on the cities' shared airshed like a dingy sombrero.
Excessive amounts of carbon monoxide, fine dust particles, and ground-level ozone put El Paso on the US Environmental Protection Agency's (EPA) list of cities not in compliance with the Clean Air Act Amendments of 1990.
''The air quality here is awful,'' says Matthew Witosky, the EPA's new border liaison in El Paso.
One reason is that Juarez residents and those of El Paso own older cars that lack modern pollution-control equipment. ''We're the dumping ground for used vehicles in the Southwest,'' says Jesus Reynoso, supervisor of the El Paso City-County air-quality program. Vehicle ages average four years in the US, seven in El Paso, and 13 in Juarez.
Many Juarez residents buy a clunker in the US for a few hundred dollars, drive it till it drops, abandon it, and buy another. This ''disposable fleet,'' lacking documents and pollution controls, numbers more than 60,000, Mr. Reynoso says. (The peso devaluation has stalled the practice, though. Purchases at El Paso used-car lots have fallen 80 percent.)
In recent years, however, air quality has shown improvement. El Paso has had no violations for particulates or fine dust in two years and for carbon monoxide in a year. Heat causes ground-level ozone, or smog, to form, but last summer when temperatures topped 100 degrees F. for 24 days in a row, the city exceeded ozone limits on just five days.
Officials attribute the progress to wintertime sales of cleaner-burning oxygenated gasoline in El Paso, and to road-paving projects and vehicle-inspection programs in both cities. Changing the spark plugs and points in a Juarez vehicle, Reynoso says, can cut its emissions 99 percent.
Inspections programs lacking
But more needs to be done, say environmentalists. Seventy percent of Juarez's streets are unpaved, and traffic thereon launches dust particulates skyward. Both cities lack strong inspection programs, but their commitment is questionable.
For instance, in 1994 Juarez residents could not renew their automobile registration without first obtaining an inspection sticker. That led to scenes like one in December at a Juarez fairground that had been turned into a one-stop testing and registration center.
Hundreds of drivers, their vehicles idling smokily, waited in line more than five hours for the five-minute inspection. One was Joel Antillon, a maquiladora worker who huddled in the cab of his splotchy red 1975 GMC pickup with his mother, pregnant wife, and two sons.
Suddenly the truck, purchased in Texas for $600, began to spew water. Mr. Antillon climbed into the cavernous engine compartment and shut off the flow with a pair of pliers.
''It has a good engine,'' Antillon says, confident the truck would pass.
''But it's ugly!'' his mother laments.
Even if Antillon's truck passed, half of the 200,000 vehicles tested last year failed, and Juarez mechanics lack training in how to repair the problems.
Registration income dropped so drastically that the state of Chihuahua faced a cash crunch. This year, inspection enforcement is still mandatory but not a registration prerequisite. The state has turned over inspection enforcement to Juarez. Its success remains to be seen.
Meanwhile, the task force has attacked the Juarez knowledge gap. Using EPA grants and donated equipment, it helped arrange for Colorado State University to train mechanics instructors to diagnose and repair emissions problems. The instructors, in turn, will retrain Juarez mechanics.
''It's going to help clean the environment,'' says instructor Agustin Griego at a December ribbon-cutting ceremony for new diagnostic equipment at the Cecati No. 19, a technical school in Juarez.
North of the border, the future of vehicle inspections is in doubt. The inspection program that began in 1987 was riddled with fraud, says Archie Clouse, manager of the air program for El Paso at the Texas Natural Resources Conservation Commission (TNRCC). One of his own employees, needing an inspection sticker, had a relative simply buy one, Mr. Clouse says.
Texas had intended to implement a tougher inspection program in El Paso. But new computer models have convinced the TNRCC that, were it not for Juarez, El Paso would meet Clean Air Act standards with no inspection program at all. It has asked the EPA to grant the city a waiver.
Clean methods for brickmakers
After cars, the second-leading source of air pollution is the Juarez brickmaking industry. Scattered throughout the city are 266 primitive brick kilns fueled by sawdust and sometimes old tires or motor oil.
A Juarez-based nonprofit organization called FEMAP has established a school to teach brickmakers more efficient and environmentally friendly methods, such as using natural gas for fuel. Another goal, assisted by the task force, is to relocate the brickmakers to a common area with modern facilities. One advantage for brickmakers would be more bargaining power with customers and suppliers. Higher earnings would help make less-polluting practices more affordable.
A December visit to Pancho Villa, a Juarez slum where crude kilns intermingle with dwellings made from shipping pallets or broken-down buses, showed the difficulties of changing old ways.
''It's hard, and the weather is cold,'' says Gavino Filomeno Garcia as he waited for his kiln to cool. Mr. Filomeno had burned a recommended mixture of natural gas and sawdust until the government-set price for gas doubled. ''Forget it,'' was his reaction.
Now he burns only sawdust. That's now illegal, but he has learned how to control the burn so that it does not make the dark cloud that attracts attention.
''When they don't see dark, nobody bothers me,'' Filomeno says. Other brickmakers at Pancho Villa don't even trouble with that precaution, allowing black billows to escape.
The most ambitious aim of the task force is to nudge the US and Mexico toward creating the world's first ''international air quality management district.'' This entity would have the jurisdiction to set aside national and state laws and to impose and enforce a single set of environmental regulations.
''Only a cooperative joint strategy guarantees the lowest-cost solution,'' says Environmental Defense Fund senior scientist Peter Emerson, who helped found the task force to agitate for management district status. He says negotiations between the two countries could begin this spring. The optimum outcome would be an ''Annex Six'' to their 1983 La Paz agreement, which authorized joint efforts to solve border environmental problems.
A regionwide cleanup strategy
Meanwhile, Texas will be working to fulfill its Clean Air Act obligations for El Paso by developing an airshed-wide cleanup strategy by 1998, then seek to enlist Mexican support.
''That process is not going to solve the problem'' even by 2098, Dr. Emerson warns. ''We have to face that. Mexico doesn't have a real interest in this until you get them involved.''
A big advantage of an air quality management district would be local decisionmaking authority, free of the centralized bureaucracy of Mexico City. The district would also end embarrassing disparities in regulation, justified or not.
''The worst setback is the fact that the attitude in El Paso for environmental controls has gone out the window,'' Reynoso says, referring to the political efforts to end the city's vehicle-inspection program.
''That is being felt in Juarez,'' he adds. ''People there say if El Paso is relaxing environmental laws, why are the laws getting stronger in Juarez?''