Morning Business Memo:

Reports that central banks around the world stand ready to prop up the financial system in case of a possible freeze up sent global stock market averages higher. Huh? Sounds strange, doesn't it? Global investors are said to be on edge as Greece prepares for its weekend election. Parties opposed to the tough terms of the financial bailout could take control of the Greek government. That might lead to a withdrawal from the single currency euro, threatening the failure of a number of banks. Markets have been dogged for weeks by worries about Europe. After steady gains in the first three months of the year, stock prices have been volatile. Now central banks appear to be talking to each other, standing by for coordinated action. "Obviously where there's smoke there's fire, and the confirmation of that news was actually positive to the market," Wall Street economist Carey Leahy says. Central banks "were telling us the obvious, and the obvious is that if things go very badly next week, central banks will be prepared to provide liquidity."

Soot from exhaust fumes has been linked to thousands of premature deaths each year, and the aggravation of respiratory illnesses, heart attacks and strokes. The U.S. Environmental Protection Agency is proposing new air-quality standards that would lower the amount of soot allowed from diesel trucks, buses, power plants and other sources. The long-delayed rule is expected to be made public today. Eleven states, including New York and California, filed suit earlier this year to force a decision. The states and the American Lung Association say current standards jeopardize public health.

A new study says U.S. retail sales of video-game hardware, software and accessories fell 28 percent in May, the 6th straight month of decline. Sales of console and portable software - the video games themselves - fell 32 percent from a year earlier, while sales of hardware fell 39 percent. Market tracker NPD Group tracks sales of new physical product, about 50 percent to 60 percent of the total spending. Excluded are sales of used games and rentals as well as digital and social-network spending.

Is this a big deal or not? Microsoft is being secretive about a "major" announcement it plans to make in Los Angeles Monday. The company invited media to an afternoon event, but it says it won't divulge the location until that morning. In an email, the company says, "This will be a major Microsoft announcement - you will not want to miss it."