甲醛
Formaldehyde

context: zh_tw: 在高層大氣過程中貢獻環境中總甲醛的 90％。甲醛是在甲烷以及其它碳化合物氧化 (或燃燒) 的中間體，例如在森林火災，汽車尾氣和菸草煙霧。透過陽光和氧氣的大氣作用，在大氣中產生的甲烷和其他碳氫化合物，成為煙霧的一部分。甲醛也已在外層空間檢測到。
en: Processes in the upper atmosphere contribute up to 90% of the total formaldehyde in the environment. Formaldehyde is an intermediate in the oxidation (or combustion) of methane, as well as of other carbon compounds, e.g. in forest fires, automobile exhaust, and tobacco smoke. When produced in the atmosphere by the action of sunlight and oxygen on atmospheric methane and other hydrocarbons, it becomes part of smog. Formaldehyde has also been detected in outer space (see below).
qas: question: zh_tw: 與爆炸意思相似的是？
en: What is synonymous with combustion?
answers: zh_tw: text: 氧化
en: text: oxidation

context: zh_tw: 甲醛若在空氣中的濃度超過 0.1 mg/m3，會導致眼睛和黏膜細胞的傷害。在體內，甲醛可能導致蛋白質不可逆的與 DNA 鍵結。動物實驗顯示暴露在大劑量的甲醛中會使得鼻子與喉嚨致癌的機率增加。然而在大部份的建築內甲醛含量濃度不足以產生致癌性。美國國家環境保護局將甲醛分類為可能致癌物質，國際癌症研究機構（IARC）則將其分類為人類致癌物質。
en: The formaldehyde theory of carcinogenesis was proposed in 1978. In 1987 the U.S. EPA classified it as a probable human carcinogen, and after more studies the WHO International Agency for Research on Cancer (IARC) in 1995 also classified it as a probable human carcinogen. Further information and evaluation of all known data led the IARC to reclassify formaldehyde as a known human carcinogen associated with nasal sinus cancer and nasopharyngeal cancer. 2009 and 2010 studies have also shown a positive correlation between exposure to formaldehyde and the development of leukemia, particularly myeloid leukemia. Nasopharyngeal and sinonasal cancers are relatively rare, with a combined annual incidence in the United States of < 4,000 cases.  About 30,000 cases of myeloid leukemia occur in the United States each year. Workplace exposure to inhaled chemicals is among the most important risk factors for sinonasal cancers. Professionals exposed to formaldehyde in their occupation, such as funeral industry workers and embalmers, showed an increased risk of leukemia and brain cancer compared with the general population. Other factors are important in determining individual risk for the development of leukemia or nasopharyngeal cancer.In the residential environment, formaldehyde exposure comes from a number of different routes; formaldehyde can off-gas from wood products, such as plywood or particle board, but it is produced by paints, varnishes, floor finishes, and cigarette smoking as well. In July 2016, the EPA released a prepublication version of its final rule on Formaldehyde Emission Standards for Composite Wood Products. These new rules impact manufacturers, importers, distributors, and retailers of products containing composite wood, including fiberboard, particleboard, and various laminated products, who must comply with more stringent record-keeping and labeling requirements.The United States Environmental Protection Agency (EPA) allows no more than 0.016 ppm formaldehyde in the air in new buildings constructed for that agency. A U.S. Environmental Protection Agency study found a new home measured 0.076 ppm when brand new and 0.045 ppm after 30 days. The Federal Emergency Management Agency (FEMA) has also announced limits on the formaldehyde levels in trailers purchased by that agency. The EPA recommends the use of "exterior-grade" pressed-wood products with phenol instead of urea resin to limit formaldehyde exposure, since pressed-wood products containing formaldehyde resins are often a significant source of formaldehyde in homes.
qas: question: zh_tw: 甲醛被歸為什麼類別？
en: what is formaldehyde classified as?
answers: zh_tw: text: 可能致癌物質
en: text: a probable human carcinogen