As China’s economy continues to grow at an incredibly rapid rate, so are its pollution levels. The U.S. embassy said earlier this week that the thick smog covering Beijing had gone “beyond” measurable pollution levels.

The assessment by the embassy found that the pollution levels were or “beyond index,” which essentially means that air quality in the city had dropped below the worst level on the scale.

In fact, a Chinese official at the Beijing Environmental Bureau, who refused to be named, even warned people to stay indoors and avoid outdoor activity. “Obviously elderly people and children should not go outside,” she told AFP.

Air quality in Beijing had reached level five — the worst rating — according to the Bureau. Particle pollution, a lack of wind and high temperatures had added to the problem, a report said. Visibility in some parts was down to just 200 meters.

China has already surpassed the U.S. when it comes to the worst pollution levels in the world, and considering its rapid rate of growth — that number is only going to grow before it comes down. Currently over 70 percent of China’s electricity comes from coal plants, and the country is continuing to build more of them. As a result, China is now responsible for 24 percent of the global fossil emissions of CO2.

Even building seemingly green infrastructure initially produces emissions and China’s investment into large-scale infrastructure projects has led to the biggest increase in pollution.

“When China invests in roads or buildings, this causes large emissions, as industries like cement and steel industries are very emission intensive”, Glen Peters, a senior research fellow at CICERO, told Green Car Congress.

China is also supposed to see a surge in vehicular traffic to more than 1.2 billion by 2025, from 750 million today. Even as the country is giving out huge stimulus funds to see an increase in electric vehicles on the road, for now those are most likely to be powered by electricity produced from coal-plants.

For any true dent in China’s emissions standards, the reliance on coal is going to have to decrease. As more of their green-projects get completed — and as electricity starts getting produced from renewable sources — China will hopefully see a drop in emissions.