To tackle air pollution in the Jing-Jin-Ji urban region, a new control model called HCML was applied. It involves different levels of government working together to fight pollution. Monitoring six different pollutants in 13 cities showed that pollution levels dropped significantly over two years. Except for O3, the concentrations of pollutants like PM2.5, PM10, SO2, NO2, and CO decreased. Measures like regulating industries, energy use, and even car ownership contributed to the improvement. More days now meet air quality standards, showing progress. Looking forward, actions like joint laws on pollution and public awareness campaigns will be essential for continued improvement.