For odors you need to use an activated charcoal filter. For the price the best i have found are the 3m disposable organic vapor filter. It is smaller than a gas mask and light weight, but it is still not small enough to fit in your back pocket. These also have OSHA approved dust filters that are replaceable. You should be able to purchase one at an automotive paint and body supply for less than $20 US. I have not tried one for problem bathroom odors but i believe that it would work, i have used it for other things that smell and it works really well.