There is nothing more glorious than an Israeli spring when after the rainy season, flowers bloom in riotous color, trees take on new green clothing and hybernating lawns come back to life. But it's not such a celebration for the 10 percent or so of the population who suffer from pollen allergies. Their runny noses, itchy eyes, sneezing, headaches and scratchy throats can make life a misery. Their bodies' immune system - meant to protect them against foreign invaders such as bacteria and viruses - overreact to repel tiny intruders. Each spring (and for some species in the fall), round or oval microscopic particles called pollen are released from trees, flowers, weeds and grasses. In some species, the plant uses pollen from its own flowers to fertilize itself; other types must be cross-pollinated; that is, pollen must be transferred from the flower of one plant to that of another of the same species.Insects do this for certain flowering plants, while others rely on wind. Pollen particles hitch rides on currents of air and on animals and objects that come in contact with them. Although they were created to fertilize parts of other plants, many never reach their targets but instead enter human noses and throats, triggering a type of seasonal allergic rhinitis called hay fever. Of the 20% of Israelis (or any population) who are allergic to something (including food, drugs, latex, the detritus of dust mites, pets, metals or other substances that cause their immune systems to protest), about one-half to three-fifths of them are allergic to pollen, making it the most common allergen. The chemical makeup and weight of pollen are the characteristics that decide whether they cause hay fever. For example, pine tree pollen is produced in large amounts by trees that grow all over Israel, and this would ordinarily make it a good candidate for causing allergy. But because pine pollen is heavy, it tends to fall straight down rather than scatter, so it rarely reaches human noses. But pollen from the olive tree - indigenous to Israel - is lighter and widely disseminated by wind currents. Samples of ragweed pollen have been collected 600 km out to sea and three or four km high, and ragweed pollen is produced in huge quantities; a single plant can generate a million grains of pollen a day. ALLERGY SUFFERERS often claim they are affected by colorful or scented flowers such as roses, but allergy experts note that only gardeners, florists and farmers who have long and close contact with flowers are likely to become sensitized to pollen from these plants; most people have little contact with the large, heavy and waxy pollen grains of many flowering plants because this type of pollen is not carried by wind but by insects such as butterflies and bees.Thus plainlooking trees, grasses and weeds that lack attractive flowers most commonly produce light, dry and tiny pollen grains that are carried by the winds cause the most allergic reactions. Short of remaining indoors when the pollen count is high - and even that may not help due to the lack of good insulation - there is no easy way to evade windborne pollen. PROF. MEIR SHALIT, head of the allergy and clinical immunology unit at Hadassah University Medical Center in Jerusalem's Ein Kerem, toldThe Jerusalem Post that allergenic species vary from country to country and continent to continent. "It is very well known that new immigrants, after a few years in Israel, suddenly get allergic symptoms to plants they weren't exposed to in their home country, such as olive. It also happens to Israelis who go and live abroad; in the US, for example, there are poison ivy and cedar that don't grow in Israel." Pollen counts tend to be highest early in the morning on warm, dry, breezy days and lowest during chilly, wet periods. Although a pollen count is an approximate and fluctuating measure, it is useful as a general guide for knowing when to stay indoors. For some reason, according to family doctors this reporter has spoken to and from the significant amount of e-mail from readers, the pollen allergy season seems to have come earlier this year. One such reader, who lives in Kedumim in Samaria, wrote that she never had a spring allergy when growing up in the US. But after moving to Israel as a teenager, she wrote, "I began to have allergy symptoms every spring from Passover to Shavuot. How can one find out what is blooming now?" She noted that numerous commercial Web sites in the US and elsewhere offer allergy alerts according to geographic locations and even predicting where the worst spots will be in the coming year, but that she hasn't found any sites that provide this service. Shalit says Israel is a small country, and issuing regular pollen alerts in advance or in real time costs money that nobody has allocated. Thus he knows of no service comparable to that easily available on USbased Web sites. However, the suggestion could be made to Dr. Shlomo Bar-Sela, chairman of the Israel Association of Allergy and Clinical Immunology, who works at Kupat Holim Meuhedet's allergy clinic in Jerusalem and at the occupational and environmental unit of the Hadassah-Hebrew University Braun School of Public Health and Community Medicine in Jerusalem's Ein Kerem. Shalit says allergies definitely have a genetic connection, but "we still don't know what gene is involved. It is probably several genes, rather than one. If both your parents are allergic to pollen or other substances, there is a 70% likelihood that you will be allergic as well. If one parent is allergic, the risk is about 40%. But even if you know of no allergies in your immediate family, the trait can skip generations." The environmental influences are still being debated. "Some researchers claim that if you were born on a farm and were exposed to animals and dust during the critical time of up to a few months old, you have a lower risk of developing allergies, but if your exposure began after that, your risk is greater," says Shalit. "Some say that if you have one dog or cat, you have no protection against allergies, "and that you need to have several at home to get any benefit. While some researchers have claimed that being raised in a very clean environment results in a higher risk of allergies, others don't agree at all." In addition, some scientists have claimed that the month in which you were born determines your risk (September, October and November are considered to be the most risky), but others deny a connection. There is even a dispute about whether having been breastfed protects you; some say it does, while others claim the opposite, says Shalit. However, there is little disagreement on the allergic process. Structures called mast cells are located mostly in connective tissues in the skin, tongue, the lining of the nose and intestinal tract, the lungs and upper respiratory tract. Immunoglobulin E (IgE) - an allergic antibody that is a type of protein made by the immune system to recognize and fight specific "invaders" - coats the surface of the mast cell. When an allergy-prone individual is first exposed to an allergen such as pollen, large amounts of the corresponding IgE antibodies are released, causing mast cells to release inflammatory chemicals that cause swelling of tissues, as well as histamine and other chemicals that cause itching, engorgement of blood vessels, increased secretions and bronchospasm (tightening of muscles that surround the airways). Some of these chemicals attract white blood cells known as eosinophils, which supply additional inflammatory chemicals. There is also unanimity on how to reduce your exposure: Avoid going outdoors between 5 a.m. and 10 a.m. Go outdoors instead in the late afternoon or after a heavy rain, when pollen levels are lower. Keep home and car windows closed to lower exposure, and rely on air conditioners (if you have them). Dry your clothes in an electric or gas dryer rather than hanging them outside. Take a shower, wash your hair and change your clothing after working or playing outdoors during pollen season. Keep pets that spend time outdoors - and that may have pollen stuck to their fur - out of the bedroom. Shalit notes that in the past, many people suffering from severe pollen allergies and resultant asthma moved to Arad near the Dead Sea because of the few allergenic species there. Today, breathing in the development town is still easier for such people, but it is not as allergen-free as it was 30 years ago. And since pollen can travel long distances, it is really impossible to avoid it completely. BUT WHILE there is not yet a cure to pollen allergy, there is a reliable diagnostic process, as well as effective treatment. Prick tests, in which small amounts of possible allergens are introduced under the skin, are used most commonly. If skin tests can't be performed, a radioallergosorbent blood test (RAST) - which evaluates the number of antibodies produced by the immune system - may be taken, although its results are not as accurate. Medications such as antihistamines, decongestants or a combination of both are available over-thecounter or by prescription. Nasal sprays such as topical steroids are also prescribed. But although they can really help, many people don't even bother to go to their family doctor or allergy specialist because they hold the old-fashioned notion that all these drugs make you sleepy. "This may have been true for some of the old-generation drugs, but the new generation of allergy medications don't pass the brain-blood barrier and don't cause drowsiness," Shalit asserts. "Some are approved even for pilots, which says something. And these newer drugs are included in the basket of health services." Local steroids, as in spray form, do not cause any systemic problems, so they can be taken over long periods, he adds. Asked about reports that eating yogurt at least three times a week can significantly reduce allergy attacks from pollen, Shalit says that some articles have suggested probiotics can prevent allergies or reduce their severity, but "I wouldn't say this is accepted mainstream treatment." Immunotherapy - or allergy shots with small amounts of allergens to get the immune system used to them - is recommended for relief needed over a long period of time, the Hadassah expert continues. Other recent developments are anti-IgE vaccines to prevent the development of antibodies in the allergic individual, but Shalit says that while these are readily available abroad, in Israel they are provided through the basket of services only to those who have severe allergic asthma, because of budgetary limitations. The shot is given once every two weeks or monthly, depending on dosage. Allergy vaccines of molecularly modified allergens (such as different peptides or DNA segments) are a major field of research, Shalit notes, as conventional immunotherapy can cause side effects. Sublingual therapy (allergens placed under the tongue) has been accepted in Europe for a decade, he says, but has not yet been approved by the US Food and Drug Administration or Israel's Health Ministry. Shalit concludes that although a cure to pollen allergy is not yet available, promising research is being carried out that eventually could lead to one. In the meantime, go to your doctor and don't suffer in silence.