You don't need to purchase an air purifier for your house. You have a built-in air purifier called the respiratory system.
If you think that your dishwasher is sterile, you're wrong. In fact, it's not even that clean. New research finds that both bacteria and fungi are growing in there. And even though it's very unlikely that they'll hurt you, it's still pretty gross. 
Ancient parchments decay over time, showing purple spots. The cause appears to be a succession of microbial communities: First, purple, salt-loving microbes grow. Then, other environmental microbes invade.
What happens when we die? This question is both existential and biological. While scientists cannot address the first, they certainly can address the second. What happens to your body after you die is not pretty. Alas, there is no such thing as death with dignity when the microbial Grim Reaper arrives.