Word meaning vulnerable to the elements

I would like to see what is the closest word I can get that means vulnerable to the elements. One word is preferred, as opposed to a phrase. Here is a basic example:

Steel is ____________, but titanium is not ____________.

Ideally the word is not only relevant to corrosion like in the above example, but also other elements, whatever they may be (sunlight, wind, cold, ect)

Chemlights are ____________, but flashlights are not ____________.

(in the 2nd example the element implied is sunlight. Sunlight will degrade the chemlight, but will not impact the flashlight's performance -- not that you would use a flashlight on a sunny day, assumed you used at a later date at night after exposure to sunlight)

could you be looking for pervious and impervious?

As adjectives the difference between pervious and impervious is that pervious is admitting passage; capable of being penetrated by another body or substance; permeable while impervious is unaffected or unable to be affected by.

or simply

Weatherproof

Resistant to the effects of bad weather, especially rain.

susceptible works, although that doesn't exclusively refer to susceptibility to the elements.

From Merriam Webster:

susceptible - adjective - sus·cep·ti·ble \ sə-ˈsep-tə-bəl \ - 1 : capable of submitting to an action, process, or operation a theory susceptible to proof

2 : open, subject, or unresistant to some stimulus, influence, or agency susceptible to pneumonia

3 : impressionable, responsive a susceptible mind

— susceptibleness noun

— susceptibly adverb