Thrust 2. 0: Effect of Human Activity on Exposure PM Pollutants T2 Thrust 2.0: Effect of Human Activity on Exposure PM Pollutants T2.A: PM Source Characterization Jing Qian, Clarkson University Andrea Ferro, Clarkson University Jensen Zhang, Syracuse University

Health Concerns for Indoor PM Exposure to PM contaminants indoors can constitute a potential health hazard. Resuspension events due to mechanical forces tend to result in short-term, elevated PM concentrations (Long et al., 2000, Ferro et al., 2004). Short-term (1-8 h) PM exposures have been associated with asthma symptoms, chronic obstructive pulmonary disease, and decreased heart rate variability (Delfino et al., 1998; Morgan et al., 1998; Gold et al., 2000).   Resuspended soil and dust contain pollutants and biological agents of concern, including PCBs, PAHs, phthalates, molds, pet allergens, dust mites, bacteria, lead and other heavy metals (Roberts and Dickey, 1995; Rudel et al., 2003).

Motivation for T2.A Resuspension is a major source of indoor airborne particles (Thatcher and Layton, 1995, Ferro et al. 2004) Indoor particle concentrations most sensitive to resuspension rate and track-in rate (Schneider et al., 1999). Very few field data exist for estimating resuspension rates. A wide range of resuspension rate from human activity: 10-5 -10-4 hr-1 for supermicron particles and 10-7 hr-1 for 0.4 -1 µm particles (Thatcher and Layton, 1995; Qian et al., 2006). The resuspension rate depends on many factors, such as the type of surface covering material (Thatcher et al., 2002), and the strength and pattern of activity (Ferro et al., 2004)

Objectives for T2.A Task 2.A designed to provide data for better estimates of resuspension rates from human activity and to characterize flow and PM movement Chamber study provides more control to determine impacts of factors such as particle loading, flooring type, ventilation conditions, RH, and person-to-person variability.

Hypotheses Exposure to PM2.5 in a mixing ventilation is higher than that in a displacement ventilation. Resuspension of particles is greater from old and fabric flooring material than from hard flooring. Lower relative humidity correlates with higher resuspension rate.

Experiments Conducted (n = 54) Mixing Displacement Unseeded Seeded H N O N* O* 1 4 7 9 3 5 Notes: H = hard floor; N = new carpet; O = old carpet * Experiments failed QC criteria due to the detachment of return air duct

Experimental methods Experimental Methods Floorings seeded with Arizona Test Dust (0.1-10 mm) Participant performs prescribed activities in a chamber Measure airborne particle concentration and size distribution using array of optical counters Measure vibration frequency and amplitude on raised floor Measure airflow velocity and temperature in space using an array of hot sphere probes

Chamber Instrumentation Temp = 23oC RH = 30-50% ACH = 0.5 h-1 : Probes measuring airflow velocity at 1 m and 1.5 m high. : Color index for the distance particle samplers are above the elevated floor Black: 3 cm; grey: 1.0 m; white: 1.5 m. Legend p: pDR-1000AN R: pDR-1200 G: Grimm

Prescribed Activities 30-minutes background measurement … Sitting motionless Seated, tapping feet Seated, tapping feet, upper body motions walking

Particle Distribution in Carpet Fibers by SEM Pile overall middle top bottom

Particle Concentration: Unseeded New Carpet

Particle Concentration: Seeded New Carpet

Particle Concentration: Unseeded Old Carpet

Particle Concentration: Seeded Old

Particle Concentration: Seeded Hard Floor

Two-compartment Model (1) (2) (3)

Time-dependence of Resuspension Rate

Time-Dependence of Resuspension Rate (Jian et al., 2006)

Distribution of Resuspension Rate - Log Scale (n = 48) Tukey’s Multicomparision (a = 0.05)  The mean resuspension rates among the size ranges of 0.4 - 5 mm are not statistically different from each other, but are all different from that in the range of 5 -10 mm.

Comparison of Seeded Floorings: Mixing Ventilation Other conditions: RH = 30%; Vibration Freq. = 1.0 Hz No significant difference among the flooring types. No significant size effect for resuspension from hard floor.

Comparison of Seeded Floorings: Displ. Ventilation Other conditions: RH = 40%; Vibration Freq. = 0.5 Hz Significant difference among the flooring types (2-way ANOVA gives p = 0.0038) Size effect found between 1-2 and 5-10 mm for new carpet; 5-10 and 0.4-5 mm for old carpet.

Results for Old Seeded Carpet, Displ. Vent., Rep. = 3 Two-way ANOVA (a = 0.05) p-value = 0.97 No significant difference between r for 30% and 40% RH

Exposure to PM2.5 for Various Exp. Conditions

Measured Amplitude of Vibration during Walking Nydist

Vibrational Frequency Comparison Seeded old carpet; Disp. Ventilation; RH = 44%; 52 vs. 50 kg Frequency is the Nyquist frequency found to be 0.52 ± 0.42 from 42 people’s walking (at which the signal produces the strong peaks.) Two-way ANOVA  p-value = 0.15, only 2 expt.s are compared, no conclusion drawn

Conclusions Resuspension varied under different experimental conditions, varied from person-to-person Size-resolved resuspension rates in size ranges of 0.4-1, 1.0-2.0, 2.0-5.0, and 5.0-10 mm were found ranging from 10-6-10-5 hr-1, with highest resuspension rates associated with 5.0-10 mm particles. Difference observed among carpet types, but not statistically significant. No significant effect from the two types of ventilation, or RHs of 30% and 40%.

Future work Complete data analysis. Collect real carpet fibers and compare dust loading with the test carpets (analyze 10 samples using SEM). EPA 04: Test resuspension of real dust particles from real floorings