The study, "Air pollution from industrial swine operations and blood pressure of neighboring residents," was conducted from 2003 to 2005 with 101 adults living within 2 miles of industrial pig farms. They sat outside for 10 minutes twice a day to record measurements of blood pressure. Air pollution monitors near their homes measured levels of hydrogen sulfide, a chemical in decomposing manure, and particulate matter, dust that comes from the farms.
Results showed that diastolic blood pressure increased by 2 millimeters of mercury during periods when odors were strong. High hydrogen sulfide levels increased systolic blood pressure, with a 10 part per billion rise of the chemical increasing systolic pressure by 3 millimeters of mercury. These effects were highest in men and those over 54 years old. The study found that these small increases in blood pressure could have "important public health implications," Guidry and Hessler report. It increases the risk of hypertension, stroke and heart disease. (Read more)