AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Indoor and Outdoor Endotoxins at Santiago, Chile: Spring 2012 Results
HECTOR JORQUERA, Francisco Barraza, Gonzalo Valdivia, Lupita Montoya, Pontificia Universidad Catolica de Chile
Abstract Number: 293 Working Group: Indoor Aerosols
Abstract Endotoxins are biopolymers belonging to the cell wall of Gram-negative bacteria and as such are present in indoor and outdoor environments as part of airborne particulate matter (PM); they are thought to induce inflammatory response to inhaled PM and have been found associated to asthma, lung inflammation and oxidative stress.
We carried out a simultaneous indoor and outdoor PM2.5 campaign at Santiago, Chile between mid-October and mid-December, 2012. We used Partisol 2000i samplers (Thermo Scientific, USA, 16.67 L/min) and TAS Minivol samplers (Airmetrics, Eugene OR, USA, 5 L/min) to sample outdoor and indoor PM2.5 for 24-h and 48-h integrated filter samples, respectively. Endotoxins in PM2.5 were measured following a kinetic chromogenic LAL assay. We measured a total of 44 households, including three socioeconomic statuses, and conducted a household survey as well.
Average endotoxin concentrations were 0.12 and 0.10 [EU/m$^3] for indoor and outdoor samples, respectively. Indoor endotoxin concentrations showed no significant differences across socioeconomic status (p=0.783). Average indoor/outdoor ratios had a mean and standard deviation of 1.56 and 1.59, respectively. When we plot indoor against outdoor concentrations we find that roughly half of the households present indoor sources of endotoxins while the other half do not.
We analyzed the database to understand indoor endotoxin variability in terms of household features such as presence/absence of pets, moisture, ventilation, cleaning and cooking practices and the ratio of indoor to outdoor endotoxin concentration. The presence of household pets explained the largest I/O ratio of 12, but median endotoxin concentrations did not show a statistically significant difference between pets/no pets households (p=0.563). We also found that as household ventilation increases (measured by the time windows are kept opened) I/O ratios decrease, as expected.