the thinner air, which provides less air resistance. In theory, the thinner air would also make breathing slightly more difficult (due to the partial pressure of oxygen being lower), but this difference is negligible for sprint distances where all the oxygen needed for the short dash is already in the muscles and bloodstream when the race starts. While there are no limitations on altitude, performances made at altitudes greater than 1000 m above sea level are marked with an "A". 10-second barrier The 10-second mark had been widely considered a barrier for the 100 metres in men's sprinting. The first man to break the 10 second barrier with automatic timing was Jim Hines at the 1968 Summer Olympics. Since then, numerous sprinters have run faster than 10 seconds. Ethnicity Only male sprinters have beaten the 100 m 10-second barrier, the vast majority of them being of West African descent. Namibian (formerly South-West Africa) Frankie Fredericks became the first man of non-West African heritage to achieve the feat in 1991 and in 2003 Australia's Patrick Johnson (an Indigenous Australian with Irish heritage) became the first sub-10-second runner without an African background. In 2010, French sprinter Christophe Lemaitre became the first Caucasian to break the 10-second barrier. In 2017, Azerbaijani-born naturalized Turkish Ramil Guliyev followed and in 2018, Filippo Tortu became the first Italian to run under 10s. In the Prefontaine Classic 2015 Diamond League meet at Eugene, Su Bingtian of China ran a time of 9.99 seconds, becoming the first East Asian athlete to officially break the 10-second barrier. On 1 August 2021, Su improved his Asian record at the Olympic semifinal in Tokyo with a time of 9.83. On 9 September 2017, Yoshihide Kiryū became the first man from Japan to break the 10-second barrier in the 100 metres, running a 9.98 (+1.8) at an intercollegiate meet in Fukui. British sprinter Adam Gemili, an athlete with an Iranian-Moroccan ethnic background, became the first sprinter of Middle-Eastern and North African ancestry to legally break the barrier on 7 June 2015, having done so earlier in the same season with an excessive wind reading. On 3 July 2022, Yupun Abeykoon became the first Sri Lankan as well as first South Asian sprinter in history ever to break 10 second barrier when he won the Resisprint International 2022 title in Switzerland. Yupun's achievement also meant Sri Lanka became the 32nd country in the