<P> Real or cut trees are used only for a short time, but can be recycled and used as mulch, wildlife habitat, or used to prevent erosion . Real trees are carbon - neutral, they emit no more carbon dioxide by being cut down and disposed of than they absorb while growing . However, emissions can occur from farming activities and transportation . An independent life - cycle assessment study, conducted by a firm of experts in sustainable development, states that a natural tree will generate 3.1 kg (6.8 lb) of greenhouse gases every year (based on purchasing 5 km (3.1 miles) from home) whereas the artificial tree will produce 48.3 kg (106 lb) over its lifetime . Some people use living Christmas or potted trees for several seasons, providing a longer life cycle for each tree . Living Christmas trees can be purchased or rented from local market growers . Rentals are picked up after the holidays, while purchased trees can be planted by the owner after use or donated to local tree adoption or urban reforestation services . </P> <P> Most artificial trees are made of recycled PVC rigid sheets using tin stabilizer in the recent years . In the past, lead was often used as a stabilizer in PVC, but is now banned by Chinese laws . The use of lead stabilizer in Chinese imported trees has been an issue of concern among politicians and scientists over recent years . A 2004 study found that while in general artificial trees pose little health risk from lead contamination, there do exist "worst - case scenarios" where major health risks to young children exist . A 2008 United States Environmental Protection Agency report found that as the PVC in artificial Christmas trees aged it began to degrade . The report determined that of the 50 million artificial trees in the United States approximately 20 million were 9 or more years old, the point where dangerous lead contamination levels are reached . A professional study on the life - cycle assessment of both real and artificial Christmas trees revealed that one must use an artificial Christmas tree at least 20 years to leave an environmental footprint as small as the natural Christmas tree . </P> <P> The Christmas tree was first used by German Lutherans in the 16th century, with records indicating that a Christmas tree was placed in the Cathedral of Strassburg in 1539, under the leadership of the Protestant Reformer, Martin Bucer . In the United States, these "German Lutherans brought the decorated Christmas tree with them; the Moravians put lighted candles on those trees ." When decorating the Christmas tree, many individuals place a star at the top of the tree symbolizing the Star of Bethlehem, a fact recorded by The School Journal in 1897 . Professor David Albert Jones of Oxford University writes that in the 19th century, it became popular for people to also use an angel to top the Christmas tree in order to symbolize the angels mentioned in the accounts of the Nativity of Jesus . </P> <P> Under the Marxist - Leninist doctrine of state atheism in the Soviet Union, after its foundation in 1917, Christmas celebrations--along with other religious holidays--were prohibited as a result of the Soviet anti-religious campaign . The League of Militant Atheists encouraged school pupils to campaign against Christmas traditions, among them being the Christmas tree, as well as other Christian holidays, including Easter; the League established an anti-religious holiday to be the 31st of each month as a replacement . With the Christmas tree being prohibited in accordance with Soviet anti-religious legislation, people supplanted the former Christmas custom with New Year's trees . In 1935 the tree was brought back as New Year tree and became a secular, not a religious holiday . </P>

When do christmas trees need to be taken down