Coming into contact with poison ivy, oak, or sumac is common for those living near Downingtown, PA. More than likely, you have encountered one of these plants. All three of these poisonous plants contain urushiol. This odorless and colorless oil causes the itching rash people get when they come in contact with it. About 25% of the population can have a severe reaction to this oil, which can cause severe symptoms. 15% of the population ...
