BEIJING (AP) — Schools in Beijing were ordered to keep students indoors Tuesday after record-breaking air pollution in the Chinese capital soared to up to 35 times the safety levels. The pollution spike is a reminder of China's severe environmental challenges as President Xi Jinping joins other world leaders at the Paris climate conference. Factories and construction sites were told to reduce work after the city government on Sunday issued its first orange alert — the second highest of four warning levels — in almost two years. On Monday, concentrations of airborne particles smaller than 2.5 microns in diameter, or PM2.5, peaked at 900 micrograms per cubic meter in southern Beijing.Read more on NewsOK.com