RESUMO
<p><b>OBJECTIVE</b>To make an epidemiological analysis of the effect of environment on extremely severe road traffic crashes (RTCs).</p><p><b>METHODS</b>Epidemiologic data of extremely severe RTCs associated with environmental factors, including weather, topography, road conditions and other traffic conditions in Mainland China during 2000-2001, were collected and analyzed.</p><p><b>RESULTS</b>(1) During 2000-2001, there were 3365 extremely severe RTCs with 13666 deaths, 12204 injuries and a direct economical loss of 136 million RMB. (2) Most extremely severe RTCs occurred in fine weather days and in the daytime. The high occurrence sites were plain areas, horizontal and straight roads, Grade B and C roads, ordinary road segment, and asphalt, smooth and mixed roads. (3) Compared with other RTCs, extremely severe RTCs were more likely to happen under following conditions: on cloudy, snowing, misty and blustering days; in hill and mountainous areas; on crooked and sloping roads; on freeway, Grade A, B, and C roads; mixed roads; ordinary, bridge, narrow and transitional roads; sand and dirt-roads; without traffic control measures; night without lighting. (4) Extremely severe RTCs of mountainous area or crooked and sloping roads were most severe in terms of deaths and injures per crash.</p><p><b>CONCLUSIONS</b>Extremely severe RTCs are closely related with environmental factors. Rational road programming, enhancing road establishment and improving road conditions are probably effective measures to reduce the road traffic injuries.</p>