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.
the heat island effect may generate urban temperatures 2 to 10 degrees f 1 to 6 degrees c higher than non urban areas elevated temperatures can impact communities by increasing peak energy demand air conditioning costs air pollution levels and heat related illness and mortalityrban parks cool and clean the air improve and modify local wind circulations and better regulate precipitation patterns well vegetated parks in a variety of forms and sizes mitigate the impact of the urban heat island and minimize local climate change