China's smog closes schools and highways China, which emits 6 billion tons of greenhouse gases per year, is the largest producer of emissions in the world.

Oren Dorell | USA TODAY

Show Caption Hide Caption China smog climbs to perilous levels Northern China choked under some of the worst smog this year, with Beijing's pollution soaring to 22 times healthy limits, triggering the city's second-highest air alert.

China is dealing with a blanket of smog so thick that authorities Tuesday ordered schools to keep students indoors.

A day after Chinese President Xi Jinping met in Paris with other world leaders at a climate change conference, Beijing grappled with its fifth consecutive day of air pollution. The smog blocked views across the capital, closed highways because of low visibility and caused parents to cough while worrying about their children.

"It's the worst day so far this year," Liu Feifie, 36, a mother and Internet company employee, told the Associated Press. "I feel my throat totally congested with phlegm and it feels very itchy. But I'm more concerned about the health of my 7-year-old kid."

Beijing's No. 2 Experimental Primary School told students they could study from home if they wanted, and Beijing Digital School is running classes online, China's state-run Xinhua News Agency reported.

China, which emits 6 billion tons of greenhouse gases per year, is the largest producer of emissions in the world, according to Reuters. China's president said Monday that his country would "strive to achieve" reductions in its emissions "as soon as possible."

"Tackling climate change is a shared mission for mankind," Xi said, according to Bloomberg News.

The smog will continue Wednesday in most parts of north China, Xinhua said.

Readings of tiny poisonous particles, known as PM2.5, reached into the high 600s micrograms per cubic meter in Beijing on Tuesday. A safe level is 25, according to the World Health Organization. Some suburban neighborhoods logged levels up in the 900s Monday, according to the AP.

Outside a Beijing children's hospital that was full of patients, parents and grandparents complained about the smog harming their children and worried the youngsters would become more vulnerable to illnesses, such as throat infections and the flu.

"The government is supposed to be tackling the pollution, so we need to see the effects," said Yin Lina, who brought her 5-year-old daughter to the hospital with a stuffed nose. "If in a few years the situation does not change, we will consider leaving."

China's ruling Communist Party has tightened emissions standards and invested in solar, wind and other renewable energy. But the country still depends on coal for more than 60% of its power. China plans to build hundreds of nuclear reactors to reduce its dependence on coal.

China's government-run newspapers posted articles Tuesday promising improvements — in five to 10 years.

Emissions of major air pollutants will begin to decline in five to 10 years as part of government mandates to reduce total emissions, but more time will be needed for significant improvement in China's environment, the China Daily reported.

"Volatile organic pollutant emissions" will continue to climb in the coming year and will peak in 2020, together with levels of ammonia and lead in the air, the newspaper said, citing a study by the Research Institute of Resources and Environment Policies at the State Council's Development Research Center.