Where would the world be right now without the filter? First of all, we never would have developed the way to purify plus remove dangerous materials from drinking water. Though, you can boil water to destroy bacteria, you still need to filter it. Learning how to clean large amounts of water plus filter them for public consumption played a huge role in humanity growing as large and fast as it did. But as our cities became larger and more populated because of access to water, there emerged a need for a different kind of filtration system, but air filters were needed at factories and cities to purify the air and keep disease from spreading rapidly due to bad air quality. This is not an air conditioner we are talking about here. It was not designed for cooling off the buildings or businesses. This was just an air filtration unit provide purification and ventilation for the air. These early systems were far from perfect; however, they were all based on the right idea of filtration, and over the years, air filter technology has gotten better. HEPA air filters remove over 99% of particles, dander, and pollen from the air. Cleaner, fresher air helps promote higher air quality which gives us better cardiovascular health. All current Heating, Ventilation and A/C units come with air filters, and most come with dehumidifiers as well. Who knows what Heating, Ventilation and A/C systems will be featuring in the next 30 years.