in humans to the development of coronary disease and angina. Environmental abundance Most production, use, and emissions of HFC-152a have occurred within Earth's more industrialized and populated northern hemisphere following the substance's introduction in the 1990s. Its concentration in the northern troposphere reached an annual average of about 10 parts per trillion by year 2011. The concentration of HFC-152a in the southern troposphere is about 50% lower due to its removal rate (i.e. lifetime) of about 1.5 years being similar in magnitude to the global atmospheric mixing time of one to two years. See also List of refrigerants IPCC list of greenhouse gases Canned air References Fluoroalkanes Refrigerants Greenhouse gases Organic compounds with 2 carbon atoms