Other causes have been attributed to contaminants produced by outgassing of some types of building materials , volatile organic compounds ( VOC ) , molds ( see mold health issues ) , improper exhaust ventilation of ozone ( byproduct of some office machinery ) , light industrial chemicals used within , or lack of adequate fresh-air intake\/air filtration ( see Minimum Efficiency Reporting Value ) .
Other causes have been contaminants produced by outgassing of some types of building materials , volatile organic compounds ( VOC ) , molds ( see mold health issues ) , improper exhaust ventilation of ozone ( byproduct of some office machinery ) , using light industrial chemicals in the building , or lack of adequate fresh-air intake\/air filtration ( see Minimum Efficiency Reporting Value ) .