Human inhalation exposure to fine particulate matter (PM2.5), including the PM2.5 of outdoor origin, predominantly occurs indoors. To limit penetration into buildings, ventilation standards often require filtration air with a minimum efficiency. Nevertheless, filter selection recommended by is based on annual average concentrations without considering seasonal or diurnal f...

Condenser r-meter thimble chambers of various types have been calibrated against a standard free-air ionization chamber to indicate the wavelength dependance of their readings after exposure to X-rays excited by potentials ranging from 10 to 200 kilovolts. X-ray tubes with low inherent filtration are used. Calibrations are conducted for minimumfilter conditions, and the effect of added filtrati...

The corona-charged fibrous electrets are dielectric materials exhibiting quasi-permanent electrical charge imparted by means of corona discharge process. The electrical charge in the electret fibrous materials has been utilized to capture hazardous particles from complex air streams. Air filters of this kind are widely used as respirators and face masks in personal protective equipments, dust c...

Inhaling indoor air is the primary means by which humans are exposed to bioaerosols. Considering bacteria, fungi, and viruses, this study reviews the dynamic processes that govern indoor concentrations and fates of biological particulate material. Bioaerosol behavior is strongly coupled to particle size; this study emphasizes the range 0.1-10 μm in aerodynamic diameter. The principle of materia...

Higher-efficiency HVAC filters generally have a higher pressure drop and are widely assumed to increase energy consumption in smaller air conditioning systems. To explore the effects of filters in real buildings, we monitored 17 residential and light-commercial forced air cooling systems in Austin, TX. Measurements were made once per month for one year at each site with filters from three diffe...

Bioterrorism is an area of increasing public health concern. The intent of this article is to review the air cleansing technologies available to protect building occupants from the intentional release of bioterror agents into congregate spaces (such as offices, schools, auditoriums, and transportation centers), as well as through outside air intakes and by way of recirculation air ducts. Curren...