I work in a factory where we process frozen broccoli, we receive the raw material from fields and it is in storage about 4 or 5 days before we process it. I need information about the consequences of presence CO2 (around 800 ppm) and CO (around 100ppm). The temperature in the cold storage is around 10 C and the humidity around 85%. (A.A.)
The CO2 and CO levels will not detrimentally affect the quality of the broccoli, however storage at 10C for 4-5 days will result in some loss of nutrients even if yellowing is not yet visible. Dropping the temperature to 5C or lower would be beneficial. See the graphs below to put temperature into perspective. The humidity is of importance only if you are getting dehydration of some of the product during that period. Often the top crates in a room will suffer dehydration and may need to be covered (with empty containers or carton covers). Slight dehydration is not an issue if the broccoli is frozen. I am mainly thinking about the quality of the product for fresh market.
Also since CO is toxic to humans, there are guidelines about worker exposure in relation to concentration. Although you are no doubt aware of this, here is a link to an about CO. I hope this is helpful.