Dust mite allergies are remarkably common, with more than 20 million Americans suffering from them. Chances are, there are at least a few dust allergy sufferers in your office, and if you're not careful about keeping the place clean, they probably find work rather grueling as they sneeze their way through the day. If you want to keep your employees healthy (and decrease the number of sick calls you get), then make sure you're cleaning these often-overlooked dusty areas in the office.

Above the hung ceiling.

In most offices, the hung ceiling is put into place and then never messed with again. When the dust accumulation gets pretty severe after a few years, dust particles start slowly trickling down from between the panels, or they might get dislodged when someone needs to adjust a light or a vent. Since the ceiling is located above everyone, when these dust mites and dust particles tumble down, they are dispersed easily through the air and breathed in by everyone.

Arrange to have your maintenance team or an outside cleaning company clean above the hung ceiling at least once a year. This will be a pretty big project if it has never been done before, so plan it for a weekend when no one will be around, and if your own cleaning crew is tackling the work, make sure they have dust masks to wear.

Behind computers and stacks of files.

Stacks of files that have not been moved in months and desktop computers that were plopped into place and never shifted are sure to be hiding some dust. When a draft blows through, that dust will become airborne. Cleaning behind these items should not be a major project; have your cleaning crew start at one end of the office and tackle a little each day until they're done. Then, keep up with the issue by moving files and desktops and cleaning behind them on a monthly basis.

Behind and under furniture.

Desks and cabinets that have been in the same place for years are likely also concealing dust. Even if your cleaning staff tries to periodically vacuum behind them with a wand attachment, you'll be surprised how much dust is still back there when you pull the furniture out. Maybe it's time to completely re-arrange the office. Pull all of the furniture out, clean behind it, and then experiment with a new furniture arrangement. Of course, if you and your employees like things the way they are, you can always put things back in their original places, too.

Inside the ducts.

Many duct systems are filled not only with dust, but with mold growth, which is another common allergen. Cleaning the ducts is not a job you can tackle yourself. You will need to hire an experienced cleaning team or HVAC specialist to do so, since specialized tools are needed. Try to do this on the weekend, so any dust that gets dislodged has time to settle out of the air before your employees return. Don't be surprised if everyone feels a whole lot better once the ducts are cleaned, since when they are dirty, they spew dust mites through the air every time the air conditioning or heat turns on.

Along baseboards.

In many offices, the cleaning staff does a quick job of vacuuming the floors. They don't use a separate attachment and remove dust from along the baseboards. Talk to the cleanings staff and ensure they are doing this once a month or so. Otherwise, the dust accumulation can get pretty bad, and the second someone opens a window or turns on a fan, that dust ends up all over the room.

If you focus on cleaning the areas above, your office will be a more comfortable environment for those with dust mite allergies. Once the place is clean, be sure to keep it that way. A healthy work environment is a happy work environment, and happy workers make your company stand out amongst the competition.