Rapid technological advances in the pharmaceutical industry have focused attention on a vast number of moisture control issues. For example, the presence or absence of a specific amount of moisture in the processing area may be required to grow certain organic cultures. Or, the presence of moisture may be absolutely necessary for the manufacture of a particular drug. Similarly, the absence of moisture may be equally imperative for the production of some other drug. Strict control of moisture is a key factor in the manufacture of most drugs and medicines.

As with foodstuffs, many materials used to produce pharmaceuticals have a physical affinity for moisture. This can cause lumping or caking of powdered material. Further, some powders that are bound into a capsule or formed into a tablet under high pressures will adhere only when in a dry state, Humidity can cause a tablet to crumble, and in some cases, it can cause the drug to decompose and diminish in its therapeutic value.

To assure consistently high quality drugs, the processing area and machinery must be surrounded by air whose dryness is accurately known and controlled.

Pharmacy is the science and technique of preparing and dispensing drugs. It is a health profession that links health sciences with chemical sciences and aims to ensure the safe and effective use of pharmaceutical drugs.

Now, most of the substances used in medicine are hygroscopic and moisture absorption during the manufacturing process will affect the final weight, quality and durability.

Dry environment generally allow for faster production, better quality product and longer shelf life. Most Tablet-making process require moisture control beetween 20-35% RH at 21-24' C.

Moisture sweating, particularly on moving parts, can be very detrimental. For example sweating occurs as equipment is being cooled in polymer injection molding operations. Because molds are artificially chilled, dehumidified air must be used to surround them, or condensation will form… and water is one item that must be avoided here.
Another example is the water pumping station whose numerous valves, fittings and other parts may become rusty and need periodic painting or replacement. In a large facility, a major effort of repainting, replacement, and mopping up may be necessary to deal with condensed water.
Insulating the pipes helps reduce the amount of dripping condensate. However, valves and other such fittings that remain uninsulated present a constant maintenance problem. Dry air in the pumping station and pipe gallery provides a solution.

When a nuclear power plant is shut down for refueling-a process that can take a whole year dehumidified air can keep such non-nuclear components as boilers, condensers, and turbines rust free. For fossil fuel power stations, the laying-up process is usually part of putting power production on hold. Here the reason may be for furnace or boiler repair or the lay-up might be due to less expensive power becoming available from a nearby source. During these periods, a flow of dehumidified air in the facility is used to prevent
rust or other harmful, moisture-related problems.

Ships can also be layed-up. Some are “mothballed” for indefinite storage. Many such vessels are later reactivated, cleaned-up, and set
to sea. During the interim, dehumidified air keeps rust, mildew, and corrosion from ruining the engine room, cargo holds, and living or working quarters. Other ships are part of the “ready fleet”-anchored at sea, fully equipped, and ready for a crew to come on board and set sail almost immediately. These, too, are protected by a steady flow of dehumidified air that is continuously pumped throughout the vessel.

As air is compressed, the dew-point or temperature at which water will condense is raised. Therefore, to get dry air we need to find a way to cool the compressed air. But costs can be prohibitive because equipment, space, and auxiliary equipment are necessary for the process. However, if compressed air is already used in the primary operation and only very small amounts of dry air are needed for humidity control, compression may be a feasible route to dry air.

When air at extremely high pressure (over 200 lb/sq in) is needed, small quantities of high pressure air may be used to maintain small enclosures at the required moisture level. It is also possible to use small amounts of the high pressure air with a smaller air facility to control moisture on a limited scale.