I'm not exactly sure what your end goal is, but I'm going to assume you format your x,y variables in a nx2 matrix, so z = [x,y] where x:= nx1 and y:= nx1 vectors.
So what you are asking is for a way to separate out data points where y is outside of 10-35 range? For that you can use a conditional statement to find indexes where that occurs:
index = z(:,2) <= 35 & z(:,2) >= 10; %This gives vector of 0's & 1's length nx1
z_inliers = z(index,:); %This has a [x,y] matrix of only inlier data points
z_outliers = z(~index,:); %This has a [x,y] matrix of outlier data points
If you want to do this according to standard deviation then instead of 10 and 35 do:
low_range = mean(z(:,2)) - std(z(:,2));
high_range = mean(z(:,2)) + std(z(:,2));
index = y <= high_range & y >= low_range;
Then you can plot your pdf's or whatever with those points.