In urban and suburban settings, indoor ozone exposures can represent a significant fraction of an individual's total exposure. The decay rate, one of the factors determining indoor ozone concentrations, is inadequately understood in residences. Decay rates were calculated by introducing outdoor air containing 80-160 parts per billion ozone into 43 residences and monitoring the reduction in indoor concentration as a function of time. The mean decay rate measured in the living rooms of 43 Southern California homes was 2.80 +/- 1.30 hr-1, with an average ozone deposition velocity of 0.049 +/- 0.017 cm/sec. The experimental protocol was evaluated for precision by repeating measurements in one residence on five different days, collecting 44 same-day replicate measurements, and by simultaneous measurements at two locations in six homes. Measured decay rates were significantly correlated with house type and the number of bedrooms. The observed decay rates were higher in multiple-family homes and homes with fewer than three bedrooms. Homes with higher surface-area-to-volume ratios had higher decay rates. The ratio of indoor-to-outdoor ozone concentrations in homes not using air conditioning and open windows was 68 +/- 18%, while the ratio of indoor-to-outdoor ozone was less than 10% for the homes with air conditioning in use.

Estimating personal exposures to air pollution is a crucial component in identifying high -risk populations and determining efficient control strategies. Because of the difficulty of comprehensively measuring personal exposure, data on air pollution patterns in homogenous microenvironments linked with activity data are often used as surrogates. In this study, we focus on strengthening the available information about nonresidential microenvironmental exposures to particulate matter and other combustion pollutants. During the summer of 2000, we measured ultrafine particles, fine particulate matter ( PM 2.5 ), and particlebound polycyclic aromatic hydrocarbons ( PAHs ) outdoors and in indoor microenvironments in Boston, Massachusetts. In indoor microenvironments averaged across sample days, mean ultrafine particle concentrations ranged from 3800 to 140,000 particles / cm 3 , with 7 -200 g / m 3 of PM 2.5 and 5 -12 ng / m 3 of particle -bound PAH. PM 2.5 indoor -outdoor ratios generally exceeded 1 in settings with high levels of human activity, with lower ratios for ultrafine particles. Cooking activities contributed significantly to elevated levels of all three pollutants. Using Linear Mixed Effects models with AR -1 autoregressive correlation structures, 10 -min average outdoor concentrations were generally weak predictors of indoor levels, with stronger relationships in an apartment without mechanical ventilation than in air -conditioned nonresidential settings. Although further study would be needed to determine whether these patterns could be generalized beyond the monitored sites, these data support previous findings and enhance our knowledge about nonresidential exposure patterns.

Two surveys of commercial transportation environments were conducted. In the spring of 1994, environmental conditions on a variety of aircraft over 22 domestic routes were monitored. In 1996, an expanded survey of 27 travel segments was performed on Boeing 777 aircraft, interstate trains, interstate buses, short-distance commuter trains, and subways. A wide variety of environmental measurements were performed including standard Indoor Air Quality (IAQ) parameters of temperature, relative humidity and carbon dioxide (CO2). Aircraft cabin air pressure was continuously measured. Contaminants including carbon monoxide, particles, and volatile organic compounds (VOC) were monitored or sampled. Surface dust was collected using modified hand vacuums, sifted and the fine particles analyzed for fungi, bacteria, endotoxin and cat and dust mite allergens. Reasonable correlation between CO2 levels and passenger loads was observed for travel segments with variable passenger loads, such as trains and subways, which is consistent with fixed volume ventilation. CO2 levels were stable for the cruise portion of flight segments, but were significantly higher during preflight and post-flight periods, suggesting lower ventilation at times of increased passenger activity. No significant differences in total fungal concentrations were noted between any transportation modes measured in 1997 or between concentrations in transportation environments and those from living room samples collected during early spring in Boston. Cat allergen was detected in most dust samples with the highest dust mite concentrations recovered from a train. Particle concentrations were highest in subways and generally higher on all ground transportation environments than on aircraft. VOC s associated with mobile sources were higher for ground transportation than for aircraft as were many other VOCs. Exceptions were acetone and ethyl alcohol, which were higher on aircraft.

No abstract

No abstract

No abstract

We conclude that although ambient PM(25) measurements provide an adequate indicator of outdoor air quality for use in epidemiologic studies, they may not be adequate for studies on relationship between non-ambient pollution and health effects. Since only about 20% of variability in personal B[a]P exposure could be explained by personal PM(25) level, the extrapolation of personal exposure to B[a]P from personal PM(25) data may be greatly underestimated.

No abstract