Filters have a efficiency rating called MERV, ( Minimum Efficiency Reporting Value). The higher the MERV rating , the cleaner the air and the better the equipment protection. Control dust, dirt, and pollen with high quality filters and/or air cleaners.
Control direct sun through windows, depending on the season and local climate. During cooling season, block direct heat gain from the sun shining through glass on the East and especially West sides of the facility. Depending on your facility, options such as "solar screens," "solar films," awnings, and vegetation can help keep facilities more cool. Over time, trees can attractively shade the facility, and help clean the air. Interior curtains or drapes can help, but it's best to prevent the summer heat from getting past the glass and inside