Elemental analysis of infant airborne particulate exposures.

Air pollution is hypothesized to have negative impacts on infant pulmonary health because of infants' increased rates of respiration and ongoing lung development. The severity and type of impact may differ depending on elemental concentrations. We conducted a study of 21 infants <6 months old whose parents carried a small personal particulate monitoring device (RTI MicroPEM) and GPS unit with the infant for 7 days in January and February 2015. The study area was Utah County, UT, USA. Real-time particulate exposure levels, as well as optical density and elemental analysis of the particulate matter (PM), were compared with levels from an outdoor stationary monitor. Infants spent an average of 87.4% of their time indoors. PM levels varied widely by infant and time of day (average=19.07 µg/m3, range=0.63-170.25 µg/m3). Infant particulate exposures were not well approximated by the outdoor monitor. Infants had lower exposures to Sb, Mn, Pb, W and Fe than the outdoor monitor and higher exposures to Cd, Ni and Na. Differences were most pronounced for Na. Brown carbon was only detected by personal monitors and not by the outdoor monitor. Further research is needed to understand the potential implications of indoor elemental exposures on early respiratory development.

Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate.

Concerns about energy consumption and climate change make residential evaporative coolers a popular alternative to central air conditioning in arid and semi-arid climates. However, evaporative coolers have been shown to significantly increase indoor relative humidity and dust mite allergen levels in some studies, while showing no association in other studies. Improved measurement of temporal fluctuations in indoor relative humidity may help identify factors that promote mite growth in homes in dry climates. Dust samples and continuous indoor relative humidity measurements were collected from homes with central air conditioning and homes with evaporative coolers in Utah. Samples were collected over two seasons, winter/spring (Jan-Apr) and summer (July-Sept), 2014. Dust samples were analyzed for Der p 1 and Der f 1 using a two-site monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) analysis. Housing characteristics including age of home, occupant density, and age of mattresses, furniture, and carpeting were also measured. Positive Der p 1 or Der f 1 samples were found in 25.0% of the homes and there was no difference in mean allergen levels by type of air conditioning. Indoor relative humidity was significantly higher in homes with evaporative coolers compared to those with central air conditioning during the summer. Homes with evaporative coolers also spent significantly more time during summer above 55.0% and 65.0% relative humidity compared to central air homes, but not above 75.0%. Findings from this study suggest that increased humidity from evaporative coolers may not be sufficient to exceed the critical equilibrium humidity or maintain humidity excursions for sufficient duration in relatively larger single-family homes in semi-arid climates to support mite growth and reproduction.