Ten years ago, making methamphetamine meant a 72-hour "cooking" session that generated an intense odor similar to cat urine, which tended to limit the locations where the drug could be made.

But dealers have discovered a simpler way, removing one oxygen molecule from over-the-counter decongestant ephedrine or pseudoephedrine in a process that takes only 10 hours and can be done in locations as temporary as a motel room with only a box full of ingredients, authorities said.

Sgt. Jim Gerhardt of the North Metro Drug Task Foce said that's not good news for the innocent public, and officers have discovered such portable box labs in automobiles, apartments, storage units, an airplane hangar and, with increasing frequency, motel rooms and apartments (pictured left).

Investigators uncovered 83 such clandestine laboratories in the metro area in just the last three months, a rate of discover double that of just a year ago. Monday's discovery of a suspected drug lab at an Englewood apartment makes it 84.

Earlier this year, Denver police found two labs in one block.

"The last four years, we've doubled (the number of labs found) every year," said Sgt. Ray Booras of the West Metro Drug Task Force. "The only reason we won't double this year is that we flat run out of time to do them."

The smaller labs have changed the distribution pattern of the drug and its prosecution, said Tom Ward, assistant special agent in charge of the Denver office of the Drug Enforcement Administration.

In the past, dealers would make 5 kilograms of the drug at a time and distribute it through a network.

"Now there are guys making 2 ounces at a time, one of which is for their selves," he added. "They'll sell it to their friends 10 grams at a time. And nobody has the time to get involved in a 10-gram case."

Lt. John Costigan of the Denver police narcotics bureau said that even the smaller amounts, however, continue to pose a danger of explosion.

"We're concerned that one of these days we're going to have an explosion or a fire call to one of these motels," Costigan said.

The West Metro Drug Task force recently issued a flier to motel employees, describing tell-tale clues to people using rooms as makeshift labs.

They warned employees to be suspicious of guests who shun room service or bring in large quantities of glassware or cat box liner. The process also produces hazardous wastes, and officers have had to deal with this already too.

Denver narcotics investigator Marty Vanover was accidently exposed to some iodine during one investigation. It left him with a loss of hearing for several weeks.