Ultrafine Emissions from Heated Dust

Research Question•To study and characterize UFP emissions from heated dust, and its behavior in the indoor environment.

•The relationship between total emissions and:(i) Temperature up to which the dust sample is heated(ii) Mass of dust used (iii) Existence of an aging effect for heated dust

Results

Materials and Methods

• A small, high resolution chamber with a water-based condensation particle counter was used to measure particle number emissions. Experiments were conducted at indoor temperature and RH, with a 6 lpm flow corresponding to an air exchange rate of 33 hr -1.• Dust sample (sourced from a Davis Hall vacuum cleaner) is placed in a hemispherical bowl (made from Al foil and heating element) of diameter = 4 cm, connected to a rheostat (variable power source) and temperature probe.• The chamber was characterized to ensure:

- The bowl temperature is close to actual interior temperature of the dust- No emissions were produced from a heated, empty sample bowl and heated mineral test dust

Conclusions• Confirmed the hypothesized positive relationship between:

1. Mass of the dust being heated and emission factors (EF) 2. EF and heated dust temperature

• Emissions are generally short-lived at small dust quantities and low temperatures, but can persist for long periods of time (~22 hours) for larger quantities. Long term emissions indicate dust may be a persistent source of UFP, though not a significantly large one.

Next Steps• Further analyze and quantify the effects of these parameters on UF particle emissions• Better isolate reinforcing effects (i.e. increased mass and increased temperature) • Redesign the dust heating container to allow for more uniform heating and tighter temperature control Planar/Tube structure instead of a bowl

References1 Donaldson, Kenneth, et al. "Ultrafine particles." Occupational and environmental medicine 58.3 (2001): 211-216.

AcknowledgementsProf. William Nazaroff, fellow URAP Apprentice Ada Shaw, Negassi Hadgu and the Environmental Teaching Lab in Davis Hall.

Vineet Jagadeesan Nair, Matthew VannucciDepartment of Civil and Environmental Engineering, University of California at Berkeley, Berkeley, CA 94720

Introduction/Motivation• Ultrafine particles (UFP), which have a diameter < 100 nm, impact indoor air quality and have been linked to adverse effects including COPD, cardiovascular diseases, increased asthma incidence, strokes, heart attacks and respiratory illnesses1.• Dust has been shown to emit particles when on a hot surface, >140 °C• VOC’s from the air will deposit on indoor sources over time, causing increased emissions with time left out, known as an aging effect.

Calculations & Equations

•Emissions Rate (#particles s-1) = Concentration (# cm-3) * Volume Flow Rate (cm3 s-1)•Emissions Factor (EF): Total UFP emission per mass of dust heated = #particles, total / Mdust

Temperature (T) 145°C

168.7°C 152.2 °C 165°C 172.8°C 185°C

Mass 2.71 g 1.5 g (1.5 h) 0.15 g 1 g 2.5 g -

Total particles emitted

8.7e7 1.4E+09 7.2E+07 6.1E+08 1.5E+09 2.1E+09

Emissions Factor 3.2E+07 9.2E+08 4.8E+08 6.1E+08 5.9E+08 -

Summary of total emissions and emission factors

Photo showing (from the left): (1) Temperature Probe (2) Source of airflow (3) Sealed Airtight Chamber(4) MSP UF Particle counter