Rainfall that dampens houses over and over can foster potentially unhealthy mold and bacterial growth in walls, carpets and elsewhere.
"The crucial time for de-watering flooded areas is 48 hours," said Cole Landowski, head of Occupational Health Services for the Los Angeles County Health Department. "These microbe colonies are already in existence, and the water is one of the ingredients they need (in order) to grow."
Landowski said he has received several dozen calls about mold and bacteria problems resulting from the recent storms--more than last year.
"We have gotten an increase of calls regarding these kinds of conditions since the rains have started," he said. "We've had people report allergic, upper respiratory problems (associated with) conditions where the wetness is not taken care of and allowed to continue."
Drying or removing wet items is crucial to keeping microbes in check, he said.
Sodden carpets, furniture, drywall and insulation materials can breed bacteria within a few hours of a flood, according to a newsletter from the U.S. Public Health Department's Office of Environmental Hygiene. Fungi may start to grow within 24 hours.
Mold and bacteria growth is common in buildings damaged by rain and can lead to health problems ranging from allergies to liver problems, said Rich Byrd of Machado Environmental Corp. in Glendale, an environmental cleanup company.
Byrd said that about 10% of the population is allergic to mold. Symptoms include coughing, runny nose, watery eyes and bronchitis, he said. But unlike symptoms of a flu or cold, these allergies often improve when the person is away from the contaminated site.
A 1987 study of rain-damaged homes found that 3% harbored a type of fungus that produces toxins that cause skin rashes, and, in rare cases, can lead to liver damage, Byrd said.
The Health Department newsletter recommends removing damaged ceiling tiles and drywall within 24 hours, soaking up excess water in carpets with a "wet vacuum," and cleaning carpets, wood and upholstery with a bleach solution.
In addition, the pamphlet suggests using air conditioners or dehumidifiers to dry the home or office, and testing the building for microorganisms.