<P> In New Zealand, nearly half of (anthropogenic) greenhouse gas emission is associated with agriculture, which plays a major role in the nation's economy, and a large fraction of this is assignable to the livestock industry . Some fraction of this is assignable to meat production: FAO data indicate that meat accounted for about 7 percent of product tonnage from New Zealand's livestock (including poultry) in 2010 . Livestock sources (including enteric fermentation and manure) account for about 3.1 percent of US anthropogenic greenhouse gas emissions expressed as carbon dioxide equivalents, according to US EPA figures compiled using UNFCCC methodologies . Not all forms of meat and animal--based foods affect the environment equally . One study estimates that red meats are 150% more greenhouse gas intensive than chicken or fish . According to another research group, the ranking of some food products in relation to greenhouse gas emissions is lamb (#1), beef (#2), cheese (#3), and pork (#4). However, such ranking may not be broadly representative . Among sheep production systems, for example, there are very large differences in both energy use and prolificacy; both factors strongly influence emissions per kg of lamb production . </P> <P> Meat production is one of the leading causes of greenhouse gas emissions and other particulate matter pollution in the atmosphere . This type of production chain produces copious byproducts; endotoxin, hydrogen sulfide, ammonia, and particulate matter (PM), such as dust, are all released along with the aforementioned methane and CO2 . Furthermore, elevated greenhouse gas emissions have been associated with respiratory diseases like asthma, bronchitis, and COPD, as well as increased chances of acquiring pneumonia from bacterial infections . </P> <P> In addition, exposure to PM10 (particulate matter 10 micrometers in diameter) may produce diseases that impact the upper and proximal airways . However, farmers aren't the only ones at risk for exposure to these harmful byproducts . In fact, concentrated animal feeding operations (CAFOs) in proximity to residential areas adversely affect these individuals' respiratory health similarly seen in the farmers . Concentrated hog feeding operations release air pollutants from confinement buildings, manure holding pits, and land application of waste . Air pollutants from these operations have caused acute physical symptoms, such as respiratory illnesses, wheezing, increased breath rate, and irritation of the eyes and nose . That prolonged exposure to airborne animal particulate, such as swine dust, induces a large influx of inflammatory cells into the airways . Those in close proximity to CAFOs could be exposed to elevated levels of these byproducts, which may lead to poor health and respiratory outcomes . </P> <P> Data of a USDA study indicate that about 0.9 percent of energy use in the United States is accounted for by raising food - producing livestock and poultry . In this context, energy use includes energy from fossil, nuclear, hydroelectric, biomass, geothermal, technological solar, and wind sources . (It excludes solar energy captured by photosynthesis, used in hay drying, etc .) The estimated energy use in agricultural production includes embodied energy in purchased inputs . </P>

What is the environmental impact of eating meat