Ozone layer; wato Lemar sararin samaniya ko (Layer) garkuwa ne a yanki na Duniyar (stratosphere) cewa garwaya da mafi yawan (Sun's ultraviolet radiation). Ya ƙunshi babban taro na ozone (O 3) dangane da sauran sassan sararin samaniya, kodayake har yanzu ƙarami ne dangane da sauran iskar gas a cikin stratosphere. Layer na ozone ya ƙunshi ƙasa da kashi 10 a cikin miliyan na ozone, yayin da matsakaicin taro na sararin samaniya a cikin sararin duniya gaba ɗaya shine kusan kashi 0.3 a cikin miliyan. Ana samun mafi girman lemar ozone a cikin ƙananan ɓangaren stratosphere, daga kimanin kilomita 15 zuwa 35 (9 to 22 mi) sama da Duniya, kodayake kaurinsa yana bambanta da yanayi da yanayinƙasa. Masanin kimiyyar lissafi na Birtaniya Sydney Chapman ya gano hanyoyin photochemical da ke haifar da lemar ozone. Ozone a cikin stratosphere na duniya an halicce shi ne ta hanyar hasken ultraviolet wanda ke bugun kwayoyin halittar iskar oxygen da ke ɗauke da ƙwayoyin iskar oxygen guda biyu (O 2), ya raba su zuwa mafi kankantar iskar oxygen (atomic oxygen); da atomic oxygen sa'an nan hadawa da tsinke Yã 2 don ƙirƙirar lemar sararin samaniya, yã 3.