Local residents have scooped up emergency-supply kits, water purifiers and potassium iodide in the aftermath of the Japanese earthquake, tsunami and radiation leak, storeowners said.

The rush for supplies, while common shortly after most disasters, has taken on more of a sense of urgency, as possible windblown radiation is expected to hit parts of California by Friday.

The Santa Clara County Department of Public Health issued a statement on Wednesday urging calm and advising that no danger is imminent.

But many residents are still preparing, buying up dried foods, 72-hour survival kits and bottles of kelp tablets, potassium iodide and seaweed. Potassium iodide can help keep radioactive iodine from being taken up by the thyroid gland, which normally stores the element, according to scientists.

At Mountain View's Orchard Supply Hardware on Charleston Road, several store shelves were nearly devoid of all emergency-supply backpacks and kits on Wednesday. Only two food kits remained. Quake Hold and furniture straps, while still in supply, were also moving briskly, an employee said.

Palo Alto Hardware sales associate Will Turpin also pointed to nearly empty emergency-kit shelves. People are buying up gas and water shut-off tools and larger family-style emergency kits ($89.99), he said. The store has ordered more kits and doesn't anticipate a shortage from suppliers, he said.

Other customers are making up their own kits, he said.

"A gentleman came in the other day with a small child. He spent $200," Turpin said.

But Turpin admitted he has yet to put together his own kit. "I need to get something together. I did have some supplies, but I ate the food and I didn't replace it," he said.

At Mountain View's REI on Charleston Road, manager Bill Dougherty said the surge began two days after the earthquake, and it hasn't let up. Emergency-supply kits have fairly flown off the shelves, but with radiation looming, the focus has somewhat changed in recent days.

"Water treatment is definitely on people's minds now," he said.

Large gaps remained where water purifiers and water filters costing upwards of $100 are usually displayed. A few emergency kits remained, including some 72-hour emergency-meal kits (six entrees, three vegetables and three breakfast meals). And freeze-dried foods were still in abundance: turkey Tetrazzini, spaghetti with meat sauce, chicken teriyaki and Himalayan lentils and rice, among dozens of others.

At Mountain View Surplus on El Camino Real, manager Abdi Masoudi said in the last three days people have rushed in for ration foods and ready-to-eat meals. And "hundreds are asking for potassium iodide. We're putting in new orders," he said.

REI's Dougherty said he has noticed a somewhat disturbing trend regarding the iodide products: Some people don't understand what they are purchasing and are confused between potassium iodide and iodine. The latter is used for water purification, Dougherty said.

Country Sun Natural Foods on California Avenue and Whole Foods Market on Homer Avenue in Palo Alto were sold out of iodine-containing products.

"We've sold out of kelp tablets and seaweed," Eric Davidson, Whole Foods supplements buyer, said on Wednesday afternoon.

"Forty-eight bottles came in and they were gone this morning. We're getting many calls. It's like, 'pick up line one' or 'pick up line two' and it will pretty much be for potassium iodide," he said, hanging up the phone after turning away yet another customer. Whole Foods does not carry potassium iodide because it is more like a pharmaceutical than a natural product, he said.

At Country Sun, Addie Klein, assistant vitamin buyer, said the store has a waiting list for kelp products and is getting in only small shipments. Customers seeking to ship the supplements to families affected in Japan are at the top of the list, she said.

But residents shouldn't panic if they come away empty-handed, the Santa Clara County Public Health Department noted.

"In the unlikely event of radiation contamination in our community, California has a response plan for radiological emergencies and would have access to the national stockpile of potassium iodide, which would be recommended for those at highest risk of illness," the department said in a statement on its website.

"Distance is our friend. Given the thousands of miles between us and Japan, we do not expect to find any harmful levels of radioactivity in our state. The Santa Clara County Public Health Department is in contact with the state, and the state will let us know if the situation changes. If that were to happen, the public would be notified immediately about any precautionary measures that should be taken."

Potassium iodide can be harmful for some people, particularly those with a thyroid disease and who are allergic. People with seafood or shellfish allergies can be allergic to potassium iodide. For those with an undiagnosed condition, taking potassium iodide may cause health problems, the department noted.

Country Sun's Klein said she understands the sense of desperation some people feel. It's an urge she has suppressed herself, after seeing news about the radiation leaks, she admitted.

"I was a little frantic the first day, but then I started listening to NPR," she said. That provided better perspective and in-depth discussion on the relative risks to California, she said. "It's still a scary thing to deal with, no matter what or where you are."

More information about any radiation threat or about taking potassium iodide can be found at the Santa Clara County Public Health Department website, www.sccgov.org.