I use vinegar and water when washing out their cage or a bleach solution that I then wipe down again with water after 10 minutes. I also have had success cleaning with vinegar mixed with young living thieves oil when dealing with a rat that had chronic respiratory issues but there's really no science to back this up in rats just personal trial and error on my part. Any perfumes, Febreze's or candles in the room can also cause sneezing for a few days. Bedding can also be a source, using liners has been the only thing to help sneezy rats. And any source of steam in the room can be as well. If they don't have a wire cage ammonia from urine will build up as well.
Sneezing without any other signs of illness is most likely like not a respiratory disease but definitely watch for funny breathing noises or mycoplasm. Honestly, once you've had one rat pass from respiratory disease you tend to know what to watch out for so I think you will be fine. Its best to avoid antibiotics if not actually necessary as these can repeatedly damage a rats immune system over time.