The Air We Breath
Over the years, you've heard people screaming about air pollution. Most consider it isolated to the outdoors, but studies have shown that the air you breathe indoors has been found to be about 70 times more polluted than outdoor air. This is true because newer homes and buildings are better insulated and more tightly constructed. This creates energy efficiency, but at the sake of your INDOOR AIR QUALITY.
PLEASE READ SOME OF THE FOLLOWING STATISTICS
Relative Humidity in Sahara Desert = 25%
Relative Humidity in average heat at home = 13-16%
People on average spend 90% of their time indoors
Medical experts have ranked poor indoor air quality as one of the highest risks to human health among all types of environmental problems.
50% or more of all illnesses are either caused or aggravated by poor INDOOR AIR QUALITY
Children are more susceptible to the effects of poor INDOOR AIR QUALITY because they breathe in air faster and inhale more air per unit at body weight. Additionally, they are usually closer to the ground where concentrations of polluted air are generally higher.
One out of every six people suffering from allergies is as a direct result to bacteria and fungi in their duct systems and vents
90% of all heating, ventilating, and air conditioning systems fail due to dirt and dust buildup
A buildup as small as .050 inches of dirt on a cooling or heating coil can result in a decreased functioning efficiency of 21% which is money out of your pocket
Clean systems maintain their given efficiency by lessening running time. This is money in your pocket.
Most common fiberglass furnace filters only realize about a 7% efficiency in stopping dust, dirt, and pollen for example. While letting the other 93% pass through for distribution throughout your house. 
IMPROVING INDOOR AIR QUALITY BY HUMIDIFICATION
HUMIDIFICATION - when you heat your home, the air's Relative Humidity - which is the percentage of water vapor the air is holding, in relation to the amount it is capable of holding at a given temperature - can drop to only a fraction of what is recommended. This "desert dryness" that makes you feel uncomfortable, can cause phsyical aggravations, taking moisture from your home, and decreasing the energy efficiency of your home. Adding a humidifier can cost effectively accomplish many things.
1.   Eliminate dry nose, throat, and itchy skin and reduce static electricity
2.   Help repel respiratory problems caused by dry air
3.   Protect your home and furnishings from damaging dryness and shrinkage
4.   Reduce heating costs because you'll feel warmer at lower temperatures
5.   Even the largest residential units use less than $15 of water per heating season