Pollinating Trees

• In North America, the tree pollens typically responsible for seasonal allergies include the alder, American sycamore, ash, birch, cedar, cypress, elm, hickory, oak, poplar, Western red and walnut tree species. Depending on location, other tree varieties may be the cause of hay fever symptoms. Most people with hay fever suffer from just one type of tree pollen, although some experience cross-reactivity among the alder, beech, birch and oak tree families. While certain male cultivars, such as ash, box elder and cottonwood, produce pollen, the female trees of these species do not.
  
  

Regional Duration

• Tree pollen production varies within each region of the United States (ref. 3). In the northeast, the tree pollen season ramps up in February and runs all the way through June. For the southeast, it's February through April while the south-central region has theirs January through April. In the midwest, tree pollen production takes place in during April and May. The west coast starts their tree pollen season a month earlier than the east coast in January and finishes up a month earlier in May.
  
  

Weather

• As noted by the Weather Channel, weather conditions increase or decrease tree pollen seasons or the pollen count for a particular day. Mild winters produce earlier tree pollination and an earlier allergy season. A continuation of mild, warm weather into spring increases daily pollen counts. A mild winter followed by a late-season freeze decreases pollen production. Windy weather elevates allergy symptoms, as more pollen is distributed. While heavy rains cleanse the air of pollen for several hours during and after a storm, too little rainfall won't. Fall and winter rains increase the following spring's tree pollen count.
  
  

Preventative Action

• Pollen levels are elevated in the morning, so avoid going outdoors between 5 and 10 a.m. Perform outside activities later in the afternoon or after a heavy rain. Keeping your home and car windows closed and opt for air conditioners to keep cool lowers pollen exposure. If you hang laundry outside, use an automatic dryer during pollen season to avoid bringing those pollen particles inside the home.