When that happens, blood clots form more easily, which can block arteries and cause heart attacks.
If the Pentagon approves such a request, it notifies Congress, which can block the sale.
And just about everywhere, residents are fighting new cell-phone towers, which can block views or just look ugly.
So the run on potassium iodide pills, which can block the absorption of radioactive iodine, made little sense.
Any vents on the case or the back of the monitor should be kept unobstructed by dust or clutter, which can block air flow.
The head of the Assembly's Republican caucus, which can block any changes to the budget, has been handing out a book warning of the dangers of increasing taxes.
The technology makes use of an even greater number of small fields with tiny leaves, or collimators, which can block parts of the treatment field.
Second, above an SPF of 30, which can block 97 percent of UVB (if used in testing amounts), effectiveness increases by only 1 or 2 percent.
Some safety specialists offer glasses which can block the most common laser colours, but this can also change how the cockpit controls look to the pilot.
They also "wanted a sense of enclosure without perimeter planting," Ms. Joseph said, which "can block the view of the city".
At Cline Cellars, a Sonoma winery that has turned its rooftop solar, the only maintenance problem is dust, which can block out sunlight.
