The intensive agriculture of the province of Almeria, Spain, is a model of agricultural exploitation of high technical and economic yield based on the rational use of water, use of plastic greenhouses, high technical training and high level of employment of inputs, on the peculiar characteristics of the environment. The greenhouses (invernaderos) are located between Motril and Almeria. Especially the area of El Ejido is well known to be an agricultural hotspot. History The first greenhouse was built in 1963 and the technique was extended by the Campo de Dalías or Poniente Almeriense and later by the Campo de Níjar, in the east. The use of polyethylene as a substitute for glass had already been tested in the Canary Islands and Catalonia before. The plastic was spread over wooden posts or metal structures and secured by wire. The transparent plastic intensifies the heat and maintains the humidity. This allows harvests to be harvested one month earlier than in the open field and more ahead than in other regions, starting harvesting in December and allowing the plant growth of the autumn-winter plantings until March, doubling and sometimes tripling the number of harvests. Migrant agricultural workers Beginning in the 2000s in the El Ejido region of Andalusia, African (including large numbers of Moroccan) immigrant greenhouse workers have been documented as being faced with severe social marginalization and racism while simultaneously being exposed to extremely difficult working conditions with significant exposure to toxic pesticides. The El Ejido region has been described by environmentalists as a "sea of plastic" due to the expansive swaths of land covered by greenhouses, and has also been labeled "Europe's dirty little secret" due to the documented abuses of workers who help produce large quantities of Europe's food supply. In these greenhouses, workers are allegedly required to work under "slave-like" conditions in temperatures as high as 50 degrees Celsius with nonexistent ventilation, while being denied basic rest facilities and earning extremely low wages, among other workplace abuses. As of 2015, out of 120,000 immigrant workers employed in the greenhouses, 80,000 are undocumented and not protected by Spanish labour legislation, according to Spitou Mendy of the Spanish Field Workers Syndicate (SOC). Workers have complained of ill health effects as a result of exposure to pesticides without proper protective equipment. Groundwater pollution and drilling of water wells Groundwater is being polluted with fertilisers and pesticides. Some 5200 tons of chemical waste