Why car chrome rusts more when in garage?

[Me22]

While not using it, I stored my W124 in a locked garage for few years to protect it from the weather. The chrome trim has rusted while similar cars spent the same period outside in the rain and extreme temperatures and did not rust. Why?

 

[SL63 Mark]

Humidity

 

[peterws1957]

Humidity

This and lack of air circulation. Dehumidifier and a car bubble is a good way to protect chrome. If these are not an option, spraying the chrome with a thick coat of car wax/polish works, but always best to regularly wipe the chrome and respray, even if just storing over the winter.

 

[rifiki]

The humidity in a closed garage is often more than out side. Get a dehumidifier, the standard compressor type is OK to about 10degC