In the simplified depiction of an ice rink with an ice resurfacing machine operating shown in Figure 4-22, points 1 and 3 represent the ventilation air intake and exhaust for the entire ice rink, and point 2 is the resurfacing machine exhaust. Conditions at each point are (C indicates the concen-tration of carbon monoxide, CO):
![1423_48ef3b7d-85eb-4343-af4c-badabb2d04bc (1).png](https://secure.tutorsglobe.com/CMSImages/1423_48ef3b7d-85eb-4343-af4c-badabb2d04bc (1).png)