Using two Plantower PMS7003 sensors, one inside and the other outside a closed apartment, the author conducted a 5-day experiment to evaluate the isolation of PM2.5 and PM10. The preliminary findings indicated a minimal reduction of a closed environment of 13-17% of PM(s) with a distinct diurnal pattern of I/O ratios. The I/O ratios are consistently higher during late afternoons and lower during the early mornings. The PM(s) transport across the internal and external environments are not conclusive. The temperature shows a strong correlation with I/O ratios, in which a higher temperature in the inside environment coincides with a higher I/O ratio. The delay between PM(s) of the inside to the outside suggested the transport mechanism is slower than advection. The author concluded that with 2-3 years old buildings and considered to be well-built only provides marginal isolation to PM(s).