As part of an immune response to foreign pathogens, histamine is produced by basophils and by mast cells found in nearby connective tissues. Histamine increases the permeability of the capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues.
Where vegetation is sparse, temperature is hot. (Image: NASA) An urban heat island (UHI) is a metropolitan area which is significantly warmer than its surroundings. According to the EPA, many U.S. cities have air temperatures up to 10Â°F (5.6Â°C) warmer than the surrounding natural land cover.
trees help to reduce the urban heat island effect which contributes to increased levels of such things as higher ambient temperatures air pollution higher demands on cooling systems and health problems related to heat and pollutionrees help to reduce the urban heat island effect which contributes to increased levels of such things as higher ambient temperatures air pollution higher demands on cooling systems and health problems related to heat and pollution