i appreciate your input. you are obviously an observant and aware person. it's not hard to seperate the men from the boys on this board. the cities you list are mostly east of the mississippi. i would postulate that there is a forest type in the east that we dont have in the west. there are no oaks in the west to speak of and they are a major contibutor to pollen. the east is more industrialized, the east has more dense cities in terms of population per square mile. they say the major cause of asthma in NYC is cockroach dust. seems so many die that the dust from dead roaches permeates NYC.