A profound plunge in the number of single-family homes bought and sold in the Pittsburgh metropolitan area was most likely brought on by a severe combination of tighter lending standards that have made it more difficult to obtain mortgages and buyers who are being more cautious when job security is less certain.

September sales figures -- the most recent available -- reported by RealSTATs, a real estate information company, show area home sales fell 16.4 percent in the first nine months of this year compared with the same time frame last year, the steepest nose dive in at least 20 years.

"Banks are clearly looking at loans more closely than they did a year and half ago," said Fred Rock, a partner with Focus Investment Bankers, Downtown.

"Banks are not only looking at who meets the criteria, but at the market value of homes. There's no longer the perception that values can only go up."

Gone are the freewheeling practices that fueled no-money down mortgages, interest-only, stated-income and no-income home loans. Those and other creative financial products enabled people to obtain mortgages they might not have been able to afford.

Adjustable interest rate mortgages that were common earlier this decade are largely unheard of now. Debt to income ratios are no longer as flexible and banks are generally requiring higher down payments of around 20 percent.

Lenders acknowledge it's harder to get mortgages, but loans are still available for those who meet higher guidelines.

"The general economic downturn is causing us to look a lot closer at making loans, but we are still making loans," said Todd Brice, president of S&T Bank. "We are making sure we have an adequate down payment and an appropriate interest rate to mitigate our credit risk."

Robert Dye, senior economist for PNC Financial Services Group, said credit conditions have tightened for all types of loans, including mortgage loans.

"Lending institutions are very concerned about home buyers' ability to meet their obligations as labor market conditions continue to deteriorate and home prices continue to fall," Mr. Dye said. "These are two fundamental weights on credit markets now."

The Labor Department reported this week the number of people seeking unemployment benefits nationwide has reached 3.9 million.

Pennsylvania's unemployment rate of 5.7 percent in September still, however, fell below the national rate of 6.1 percent that month.

The nation's unemployment rate reached a 14-year high of 6.5 percent in October. Pennsylvania's unemployment rate for October is expected to be released this week.

"A lot of people have either been laid off or are concerned about job loss and are less confident about making a long-term mortgage commitment," Mr. Rock said.

Although home sales have tumbled throughout Pittsburgh, home prices keep inching higher.

The average price of a home in the five county area that includes Allegheny, Beaver, Butler, Washington and Westmoreland counties stands at $152,823, an increase of 36.3 percent since 2000.

With the exception of trendy real estate areas such as the South Side and Lawrenceville where annual home appreciation has hovered around 10 percent, Pittsburgh's relatively stable housing market continues to steadily appreciate around 2 percent to 3 percent each year.

But the declining number of Pittsburgh-area home sales in recent years could be yet another sign that this community is not entirely immune to the broad downturn in the overall economy and might be an early indication that negative price appreciation could be around the corner.

"Fewer sales mean the number of transactions aren't there, and it's only a matter of time before prices decline," said Michael Sichenzia, Chief Executive Officer of Dynamic Consulting Enterprises, a Deerfield Beach, Fla.-based firm that renegotiates mortgage debt for distressed owners. "Supply will eventually outstrip demand.

"Real estate lives and dies by the availability of cheap, readily available mortgage products," Mr. Sichenzia said. "When they are not present no matter where you live, prices will decline because sales will drop."

Many would-be home buyers also are on the sidelines holding out for prices to fall lower or have decided that their fear of losing a job in this unstable economy outweigh their aspirations for homeownership.

"There's no urgency for a lot of these folks, so they'll wait," said Bob Moncavage, owner of Priority Realty in Castle Shannon. "The normal first-time buyers are still there, and there's lots of activity. But the less urgent buyer is just sitting back."

Generally speaking, Pittsburgh also has an older population that doesn't move around as much. While the national average for a family living in one place is seven years, Pittsburghers tend to stay in their homes longer so there's not as much turnover in housing inventory.

Some housing data also could be deceiving.

Pittsburgh-area communities such as Shadyside, Squirrel Hill and Mt. Lebanon, where home prices have constantly gone up, are in stark contrast to poorer neighborhoods such as Homewood, Lincoln-Lemington and Belmar, which have either experienced no home value appreciation since 1997 or had declining prices.

Mark Price, a labor economist with Keystone Research Center in Harrisburg, said it might appear that home prices throughout the Pittsburgh area are rising when the majority of purchases are being made by affluent buyers.

"Folks with better jobs are able to weather the storms, which explains why home prices are increasing," Dr. Price said. "Those with lower priced homes may not be selling, and their home values may not be showing up in the data."

Nationwide, homeowners recently saw their real estate values drop for the seventh consecutive quarter.

According to the real estate Web site Zillow.com, home values fell 9.7 percent year-over-year in the third quarter and nearly one-third of Americans who sold homes in the past year lost money.

"The whole country has seen a huge decrease in sales," said Howard Hanna, chairman of Howard Hanna Real Estate. "It's not surprising with all that's going on in the economy and the housing industry throughout the country.

"Most markets are well off more than 16 percent. We are not in a free fall like some areas in Florida, Arizona, Nevada and California. With the kind of housing and financing market we have now, if there's a ray of light that's a ray of light."