export - Remove subscript from string

I have a list that I am using for the legend of a plot

gases = {"Air", "He", "Ar", "\!\(\*SubscriptBox[\(N\), \(2\)]\)", "\!\(\*SubscriptBox[\(CO\), \(2\)]\)"};

However, I also want to Export the data as a CSV table. When I do this the header gets all wacky:

ExportString[Join[{gases}, RandomInteger[{0, 1}, {2, 5}]], "CSV"]

"Air,He,Ar,\"N \"

  2,\"CO \"
   2
0,0,0,1,1
1,1,0,1,1"

This is obviously because of the SubscriptBox. So how can I remove these so that

Foo[gases]
    {"Air", "He", "Ar", "N2", "CO2"}

Answer

A slightly more general version of JasonB's solution:

deSubscript[string_] := StringReplace[string,
  "\!\(\*SubscriptBox[\(" ~~ Shortest[x__] ~~ "\), \(" ~~ 
    Shortest[y__] ~~ "\)]\)" :> x <> y
  ];

which also works if the string contains something other than a single SubscriptBox:

In[243]:= subscriptBoxToString["\!\(\*SubscriptBox[\(aH\), \(2\)]\)\!\
\(\*SubscriptBox[\(123\), \(3\)]\)"]
subscriptBoxToString["\!\(\*SubscriptBox[\(C\), \(2\)]\) \
\!\(\*SubscriptBox[\(NH\), \(3\)]\)"]

subscriptBoxToString["\!\(\*SubscriptBox[\(CO\), \(2\)]\)"]

Out[243]= "aH21233"

Out[244]= "C2 NH3"

Out[245]= "CO2"