Fluorescent biological aerosol particles: Concentrations, emissions, and exposures in a northern California residence

Abstract

Residences represent an important site for bioaerosol exposure. We studied bioaerosol concentrations, emissions, and exposures in a single-family residence in northern California with 2 occupants using real-time instrumentation during 2 monitoring campaigns (8 weeks during August-October 2016 and 5 weeks during January-March 2017). Time- and size-resolved fluorescent biological aerosol particles (FBAP) and total airborne particles were measured in real time in the kitchen using an ultraviolet aerodynamic particle sizer (UVAPS). Time-resolved occupancy status, household activity data, air-change rates, and spatial distribution of size-resolved particles were also determined throughout the house. Occupant activities strongly influenced indoor FBAP levels. Indoor FBAP concentrations were an order of magnitude higher when the house was occupied than when the house was vacant. Applying an integral material-balance approach, geometric mean of total FBAP emissions from human activities observed to perturb indoor levels were in the range of 10-50 million particles per event. During the summer and winter campaigns, occupants spent an average of 10 and 8.5 hours per day, respectively, awake and at home. During these hours, the geometric mean daily-averaged FBAP exposure concentration (1-10 μm diameter) was similar for each subject at 40 particles/L for summer and 29 particles/L for winter.

Indoor emissions of total and fluorescent supermicron particles during HOMEChem

“…Figure 1e shows that indoor fluorescent particle concentrations were positively correlated with the number of occupants in the UTest House (light green line) during the staggered occupancy experiments. This observation is consistent with previous studies investigating the effect of human occupancy on fluorescent particles and airborne bacteria concentrations 11,13,32 .…”

“…The fluorescent portion of coarse particulate matter has been measured in some studies as a proxy for viable airborne biological particles in ambient air and in the built environment. [6][7][8][9][10][11][12][13] These studies have mainly been undertaken using the ultraviolet aerodynamic particle sizer 4 (UVAPS) or the wideband integrated bioaerosol sensor (WIBS). Previous studies have observed autofluorescence from living cells (biofluorophores: riboflavin and NAD(P)H) [14][15][16] and from abiotic materials such as polycyclic aromatic hydrocarbons, humic-like substances, some secondary organic aerosol material, soot, optical brightening agents, fabric fibers, and mineral dust [17][18][19][20] .…”

Characterizing sources and emissions of volatile organic compounds in a northern California residence using space‐ and time‐resolved measurements

“…The second period (winter campaign) spanned 5 weeks from late January to early March 2017. A detailed description of the studied house and of the two observational campaigns has been reported . We provide a brief recap here of aspects essential for understanding and interpreting the VOC data.…”

Detailed investigation of ventilation rates and airflow patterns in a northern California residence

“…Ozone and carbon dioxide (CO 2 ) were measured simultaneously using an ozone monitor (Thermo Scientific, 49i) and a CO 2 monitor (LI‐COR, LI‐820), respectively. In addition, size‐resolved bioaerosol particles were measured using an ultraviolet aerodynamic particle sizer (TSI, 3314), as reported elsewhere …”

“…In addition, size-resolved bioaerosol particles were measured using an ultraviolet aerodynamic particle sizer (TSI, 3314), as reported elsewhere. 23 The gas-analysis instruments were situated in a detached garage about 5 m from the house. Air was continuously drawn through Figure S1).…”