There was a lot of smoke and ash in Monterey-area skies late Friday morning from a 170-acre prescribed burn in the Fort Ord back country.

The blaze, which was set about 8:15a.m., produced a towering column of smoke that cast a thick haze and deposited fine ash over much of the Peninsula until early afternoon.

Local air quality officials said they advised against doing the burn on Friday, but the Army decided to go ahead.

It was the second and final day this year of prescribed burning on Fort Ord, but Friday's blaze produced far more smoke than Thursday's fire because it consumed a bigger area and more vegetative fuel, Army spokesman Dan Carpenter said.

"The smoke got pretty thick," he said.

The Army hires contractors to set the blazes to burn off vegetation, which makes it safer for crews to detect and dispose of unexploded ordnance on former firing ranges.

On Thursday, about 100 acres were burned next to the site of Friday's fire.

But the difference between the two fires was obvious to anyone who saw the towering cloud of smoke that rose straight up from Friday's blaze before it flattened out and drifted over the Peninsula.

The Fort Ord cleanup office did field a number of calls from people who expressed concern about the blaze and wondered if it was out of control.

"We tell them it was conducted the way is was supposed to," Carpenter said.

Local air quality officials received 10 to 15 complaints about the smoky skies.

"We received a handful of calls from a number of concerned citizens, but we weren't overwhelmed," said Richard Stedman, air pollution control officer for the Monterey Bay Unified Air Pollution Control District.

One caller complained that ash was falling near the Monterey harbor, and another said the smoke was making his asthma worse, Stedman said.

Meteorological conditions were different Friday than Thursday, and Stedman said the district had recommended against burning Friday, but it was the Army's call because Fort Ord is a federal Superfund cleanup site.

"For a period of time, we know we had pretty poor quality, but it cleared out pretty quickly," Stedman said. "We don't see this as a continuing problem."

Carpenter said in an e-mail that there had been no objections to conducting the burn.

"We were well within our parameters to burn. The factors were a bit different from yesterday but within the limits we stringently set on ourselves to do these burns safely with as little impact as possible," he wrote.

The Fort Ord burns have generated criticism and controversy for a decade, during the lengthy cleanup of unexploded ordnance from hundreds of acres of former firing ranges.

Despite its dramatic appearance and the fine ash it dropped from the sky, Friday's smoke carpet didn't produce a poor air-quality day because those events are based on 24-hour averages of pollutant levels.

"For the most part, this will be a small blip in the 24-hour average," Stedman said.

The air district monitors air quality in Monterey, Santa Cruz and San Benito counties. The impacts from Friday's burn were evident in areas near Fort Ord, he said.

"We did deploy monitoring (equipment) and we will be assessing that data," Stedman said.

Carpenter said ground crews likely will go into the newly burned areas next spring to clean up ordnance. The next prescribed burns likely will be about a year from now, he said.

It costs about $250,000 a day to stage the burns, and completing them this year in two days "will save taxpayers' money," Carpenter said.

The Fort Ord cleanup website says there are still 4,000 acres in the "Fort Ord Impact Area" where vegetation must be removed over the next eight to 10 years.

The Army says it will announce the locations of 2011 prescribed burns in June.