If the job is even close to being "comparable" in terms of total compensation to the job you'd left (e.g. if 30 hours at this rate is within, say, around 70% or 80% of your prior compensation package, including benefits), then if you turn the job down, you will technically become ineligible for unemployment benefits, since you can't receive unemployment if you refuse comparable employment. (Of course, that only becomes an issue if the unemployment office somehow becomes aware that you turned down a comparable job.)