With Americans still reeling from film footage of smoke-clogged streets in Lower Manhattan, fears about air quality have increased. And so has interest in Mine Safety Appliance (MSA) - Get Report, a Pittsburgh-based company whose gear can be found on thousands of rescue workers sorting through the rubble of the collapsed buildings of the World Trade Center. The company has quietly rallied in the past two weeks.

Mine Safety doesn't have any retail customers, nor does it have any plans to court them. But corporate and government demand for the company's products, which include a variety of respirators, protective clothing and helmets, is high. Meeting that demand, however, is a challenge.

For the past two weeks, Mine Safety has been in manufacturing overdrive, hiring hundreds of temporary employees and adding extra shifts in two of its factories. "We're going flat-out, 24-7," said Dennis Zeitler, Mine Safety's chief financial officer. "We're just now getting to a point where we can supply our regular customers."

Expecting a boom in safety equipment, investors flocked to the company, the only pure play in the industry, which competes with units of

3M

(MMM) - Get Report

and

Tyco International

(TYC)

. The day before the terrorist attacks, Mine Safety traded at $30.45. Since then, the stock has soared 47%, closing Wednesday at $44.91. Meanwhile, the stocks of both Tyco and 3M lost ground: 7.4% and 8.6%, respectively.

After such a run-up, Mine Safety's stock might not have much further to go. It's trading just shy of its 52-week-high of $47.92. But take another look. Despite the recent surge in interest, the company's stock is virtually overlooked by the professional investment community. None of the major brokerages cover the company.

In addition, it issues few press releases. Even Zeitler said not to expect many public statements from Mine Safety. With nobody touting the stock, which has a paltry average daily volume of about 6,000 shares, this just could be a hidden gem -- but perhaps only for short-term traders. Indeed, when rescue workers finish clearing ground zero, the demand for Mine Safety's supplies may subside.

Even the current demand for Mine Safety might not translate into earnings. If the company can't manufacture enough products to meet demand, then that potential is wasted. And with the exception of slight Y2K-related buying, Mine Safety isn't a growth company. As a result, it hasn't taken much initiative to push its products into new channels. According to the company's Web site, its five-year sales growth is 0.61%, while earnings per share have grown just 11% during the same period.

But this year could be very different. Earnings per share for the first and second quarters of 2001 are up 14% and 163%, respectively, year over year. And since 1998, Mine Safety's fourth-quarter revenue and earnings performance have always been the best of any given year. So the best for Mine Safety may be yet to come.