Data from: Should we use ceiling fans indoors to reduce the risk of transmission of infectious aerosols?
Data files
Jul 25, 2024 version files 440.30 KB
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Data_and_R_code.zip
436.40 KB
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README.md
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Abstract
The effects of ceiling fans on the transmission of infectious aerosols remain poorly understood, leading to conflicting recommendations. We conducted repeated experiments in a well-controlled chamber with a typical mixing ventilation system at three different ventilation rates with and without ceiling fans. We evaluated airborne infection risks for short- and long-range transmission routes based on size-resolved tracer particles measured at various locations. We found that the mixing ventilation without fans only effectively diluted the airborne particle concentration for the long-range route but not for the short-range. By using ceiling fans to enhance air mixing, tracer particles were distributed more homogeneously throughout the room, leading to up to 77% reduction in short-range particle exposure while a slight increase of less than 14% in long-range exposure. Based on the dilution-based Wells-Riley model, the changes in particle concentration translated to a maximum 47% reduction in short-range infection risk and a marginal 4% increase for long-range transmission. Based on the dilution factors obtained from the experiments, we developed a decision-making tool that uses the ventilation rate, the number of individuals at short- and long-range, and the disease's transmissibility to decide whether the use of ceiling fans is beneficial. Deploying ceiling fans always reduces the concentration of particles in the short range and, assuming a relationship between particles and pathogens, this directly translates to a diminished short-range risk. Based on the modeling of the overall risk, the benefits of fans are highest when the room is ventilated according to code, when masking measures are in place, and when the pathogen is not highly contagious.
https://doi.org/10.5061/dryad.fqz612k0w
Authors: Jiayu Li, Sultan Zuraimi, Stefano Schiavon
Contact Information
Name: Jiayu Li
Institution: Center for the Built Environment, UC Berkeley, Berkeley, CA, USA
Address: 390 Wurster Hall #1839, Berkeley CA 94720
Email: jiayu.li@berkeley.edu
Date of data collection: 2021-12-03 to 2022-01-13
Description of the data and file structure
There are two main folders: data and R. data contains all the data files that have been used to generate the results in the work. R contains the R script files that are used to generate the results provided in the original work.
- Files in
data.raw_data.csvcontains raw data of tracer particle number concentration measured by the TSI OPS 3330 at different locations.n_conc: measured number concentration of the tracer particles.location: sampling locations refer to Figure 1 in the manuscript.bin: the size range of the particle diameters in µm.Da: the geometric mean of the particle diameters of the size range in µm.lower: the lower boundary of the size range of the particles in µm.upper: the upper boundary of the size range of the particles in µm.fan_1: condition of the ceiling fan 1.fan_2: condition of the ceiling fan 2.supplied_airflow_rate: the ventilation rate of the chamber in cubic meters per hour.z: sampling height in m.point_type: classification of the sampling point regarding if it is at the occupants (dummies) or in the room.loc_name: name of the sampling point.loc_type: the classification of the sampling point regarding the transmission routes.test_id: random number to differentiate different scenarios.sampling_seq: the order of sampling for each instrument.datetime: the date and time that measured the value.unit: the serial no. of TSI OPS 3330 units that were used for particle sampling
quanta_emission.csvcontains the quanta emission rates used in the manuscript.pathogen: name of pathogen.lower: the lower boundary of the quanta emission rate in quanta/h.upper: the upper boundary of the quanta emission rate in quanta/h.
em_dt.csvcontains the emission rates of tracer particles used in the manuscript.bin: the size range of the particle diameters in µm.lower: the lower boundary of the size range of the particles in µm.upper: the upper boundary of the size range of the particles in µm.e_rate: the mean of the tracer particle emission rates.e_rate_sd: the standard deviation of the tracer particle emission rates.
beta_dt.csvcontains the decay rates of tracer particles used in the manuscript.bin: the size range of the particle diameters in µm.lower: the lower boundary of the size range of the particles in µm.upper: the upper boundary of the size range of the particles in µm.fan_on_off: the conditions of ceiling fans.beta: the decay rates of the particle.r_squared: the r.squared value when fitting the decay curve.
- Files in
R.read_data.Rcontains the script that read all the data into R.ploting_themes_and_functions.Rcontains the themes and functions that need to run the R codes. Users need to install the packages mentioned in the file if they haven't done so.analysis_conc.Rcontains code for Figures 2 and 3.analysis_dilu.Rcontains code for Figure 4.anlysis_risk.Randanalysis_risk_modelling.Rcontains code for Figures 5 and 6.