@CleanAirStars @eswillwalker @JimRosenthal4 Why would it do that if it weren't actually getting dirty (from dirty outside air I assume is what you are suggesting)?
@CleanAirStars @eswillwalker @JimRosenthal4 如果它实际上没有变脏，为什么会这样做（我认为这是您的建议）？
@CleanAirStars @eswillwalker @JimRosenthal4 Why would it do that if it weren't actually getting dirty (from dirty outside air I assume is what you are suggesting)?
@CleanAirStars @eswillwalker @JimRosenthal4 如果它实际上没有变脏，为什么会这样做（我认为这是您的建议）？