A pilot investigation of the relative toxicity of indoor and outdoor fine particles: in vitro effects of endotoxin and other particulate properties.

Abstract

In this study we assessed the in vitro toxicity of 14 paired indoor and outdoor PM(2.5) samples (particulate matter < or =2.5 microm in aerodynamic diameter) collected in 9 Boston-area homes. Samples were collected as part of a large indoor particle characterization study that included the simultaneous measurement of indoor and outdoor PM(2.5), particle size distributions, and compositional data (e.g., elemental/organic carbon, endotoxin, etc.). Bioassays were conducted using rat alveolar macrophages (AMs), and tumor necrosis factor (TNF) was measured to assess particle-induced proinflammatory responses. Additional experiments were also conducted in which AMs were primed with lipopolysaccharides (LPS) to simulate preexisting pulmonary inflammation such as that which might exist in sick and elderly individuals. Significant TNF production above that of negative controls was observed for AMs exposed to either indoor or outdoor PM(2.5). TNF releases were further amplified for primed AMs, suggesting that preexisting inflammation can potentially exacerbate the toxicity of not only outdoor PM(2.5) (as shown by previous studies) but also indoor PM(2.5). In addition, indoor particle TNF production was found to be significantly higher than outdoor particle TNF production in unprimed AMs, both before and after normalization for endotoxin concentrations. Our results suggest that indoor-generated particles may be more bioactive than ambient particles. Endotoxin was demonstrated to mediate proinflammatory responses for both indoor and outdoor PM(2.5), but study findings suggest the presence of other proinflammatory components of fine particles, particularly for indoor-generated particles. Given these study findings and the fact that people spend 85-90% of their time indoors, future studies are needed to address the toxicity of indoor particles.

Particle concentrations in inner-city homes of children with asthma: the effect of smoking, cooking, and outdoor pollution.

“…This would tend to produce misclassification and result in a weaker relationship between outdoor particle exposure and health effects than might actually exist. Indoor air particle exposures could thus contribute to morbidity and mortality if the toxicity of indoor air particles is comparable with that of outdoor air, as has been found in one study (Long et al 2001).…”

Personal exposure to PM2.5, black smoke and NO2 in Copenhagen: relationship to bedroom and outdoor concentrations covering seasonal variation

“…It implies that there are other sources than the outdoor traffic that contribute to the personal exposure. This is important, as particles generated indoors might be at least as bioactive as ambient particles and therefore important when investigating impact on health effects (Long et al, 2001b). The fact that we found 'time exposed to burning of candles' to be a significant predictor of personal PM 2.5 , BS and NO 2 exposure, and 'time exposed to ETS' to be associated with personal PM 2.5 exposure helps explain why the bedroom concentration is such a strong predictor, together with the fact that the subjects spend most of their time indoors.…”

Analysis of Fungal Spore Mycotoxin and the Relationship Between Spore Surface Area and Mycotoxin Content Utilizing a Protein Translation Inhibition Assay

“…It has been estimated that humans spend between 80 -90% of their time in the indoor environment [1,2]. With such a large portion of time spent in the built environment it is accepted that a significant portion of unhealthy personal exposure to airborne contaminants can take place indoors [2].…”