The HD campus is equipped with Carrier and York fresh air purification system and upgraded the filtration system .The fresh air purification system can make the indoor room full of high clean fresh air and able to absorb formaldehyde, ammonia and other harmful gases, ensures that indoor PM2.5 index is below 10 μ g / m3. The school will monitor the air quality every day. When the outdoor air pollution is serious, the doors and windows of the classroom will be closed, and the fresh air system will be opened to ensure that the indoor air quality is always healthy and in good condition.