Geography of Uzbekistan Kazakhstan, also yielded about 60% of the total volume of Central Asia's emissions of harmful substances into the atmosphere. Because automobiles are relatively scarce, automotive exhaust is a problem only in Tashkent and Farghona. The reduction of water in Uzbekistan has resulted in soil degradation, and the spread of the salt from the evaporated Aral Sea has contaminated the surrounding soil. The soil has lost much of its water due to the increased surface irrigation. The irrigation of farmlands with water from the Aral Sea has resulted in increased salinization of the soil, causing the farmland to be less productive
Science and technology in Uzbekistan 14.1 "Note: PhD graduates in science cover life sciences, physical sciences, mathematics and statistics, and computing; PhDs in engineering also cover manufacturing and construction. For Central Asia, the generic term of PhD also encompasses Candidate of Science and Doctor of Science degrees. Data are unavailable for Turkmenistan." In 2014, Uzbekistan had a population of 29.3 million, compared to 16.6 million for Kazakhstan. The two most populous countries of Central Asia logically count the most researchers: just over 30 000 for Uzbekistan and 17 000 for Kazakhstan (in head counts), compared to a little over 2 000 for each of Kyrgyzstan