ventilation level

基本解释

For level ventilation network, parallel doubles drifts and upwards…
阶段通风网络采用两翼平行双巷双上下行通风。
Sufficient exhaust ventilation to keep dust level as low as possible.
良好的排风设施，尽可能降低环境中的粉尘。
From street level, ventilation void is now completely hidden by this inclined landscape, which also helps protectingpeople from falling down.
从街道看去，通风空间如今完全被隐藏在绿地景观后面，同时绿地景观也起到了防止行人不慎坠落的作用。