If you are an American currently traveling in Europe, you may not be reading this, but you know about it all too well: The nearly 16-month slide in the value of the dollar against the euro and the British pound has touched new depths this week.

For a third consecutive day, the dollar has reached a record level of weakness against the euro. The euro was trading in London on Thursday as high as $1.3794, Bloomberg News reported. The pound was trading at $2.0338-- its highest since June 1981. A year ago the euro was at $1.266 and the pound was at $1.84.

The dollar has also been weaker against the Japanese yen.

The deterioration in the dollar intensified after the two big credit ratings agencies, Standard & Poor's and Moody's, said on Tuesday that they would consider lowering the ratings on U.S. securities tied to subprime mortgages. The subprime mortgage market has been whipsawed by defaults, late payments and a slump in the housing market.

"Currency markets have arguably been left focusing on just one point at the moment and that's concern over the possible collapse of the U.S. subprime lending market,"  David Jones, chief market analyst at C.M.C. Markets, told the BBC.  "The result has been to put the dollar under some sustained pressure."

At the same time, both the European Central Bank and the Bank of England have recently indicated that their interest rates are headed higher, while the United States Federal Reserve is expected to keep rates steady this year. Higher interest rates typically bolster a currency's value by making fixed-income securities denominated in that currency more attractive to investors.