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. 2021 Aug 10;298:113522. doi: 10.1016/j.jenvman.2021.113522

Table 1.

Sample statistics for air quality measures, transportation variables and explanatory variables in the air quality dataset.

Variable Outcome 2017–2020
 2020
 2017–2019
 DiD DiD %
Full sample
 Before 1/22
 After 1/22
 Before 1/22
 After 1/22
Mean S.D. Mean S.D. Mean S.D. Mean S.D. Mean S.D.
Panel A. Measures of air quality and transportation in Taipei and New Taipei City
COa Concentration of carbon monoxide (ppb). 0.47 0.22 0.47 0.19 0.46 0.22 0.47 0.20 0.48 0.23 −0.02 −3.6 %
O3a Concentration of ozone (ppb). 32.60 10.78 29.98 7.45 33.42 10.49 28.20 9.49 33.85 11.16 −2.21 −6.8 %
SO2a Concentration of sulfur dioxide (ppb). 2.05 1.05 1.61 0.75 1.71 0.82 2.19 1.12 2.18 1.09 0.11 5.3 %
NO2a Concentration of nitrogen dioxide (ppb). 16.15 8.92 14.78 7.98 14.94 8.96 15.94 8.17 16.80 9.14 −0.70 −4.3 %
PM10a Concentration of particular matter <10 (ug/m3). 34.03 17.58 26.24 11.22 28.75 13.67 29.76 16.08 36.02 18.70 −3.74 −11.0 %
PM2.5a Concentration of particular matter <2.5 (ug/m3). 16.96 9.09 14.30 6.73 15.81 8.00 14.12 8.46 17.47 9.52 −1.84 −10.9 %
Carb No. of hourly cars per station (100). 3.02 6.23 3.00 2.79 3.22 6.55 3.07 7.97 2.94 5.76 0.35 11.6 %
Van/truck/busb No. of hourly vans/trucks/buses per station (100). 0.64 5.69 0.51 0.94 0.62 5.78 0.63 7.72 0.72 5.21 0.02 3.1 %
Scooterb No. of hourly scooters/motorcycles per station (100). 1.11 10.95 0.93 7.16 1.20 13.02 1.11 12.68 0.96 9.88 0.42 38.0 %
Metroc No. of daily departures & exits per station (10,000). 1.87 1.82 2.08 1.96 1.58 1.43 1.93 1.83 1.92 1.90 −0.49 −26.1 %
U-biked No. of daily departures & exits per station (100). 1.99 2.87 2.34 3.23 2.02 2.78 1.96 2.88 1.94 2.85 −0.30 −15.3 %
Panel B. Measures of air quality in mainland China
CO_China Concentration of carbon monoxide (ppb). 0.36 0.10 0.40 0.09 0.33 0.09 0.40 0.11 0.36 0.09 −0.02 −5.9 %
O3_China Concentration of ozone (ppb). 41.21 10.62 35.76 7.88 41.32 10.42 34.08 10.26 43.79 9.89 −4.14 −9.5 %
Variable Outcome 2017–2020
 2020
 2017–2019
 DiD DiD %
Full sample
 Before 1/22
 After 1/22
 Before 1/22
 After 1/22
Mean S.D. Mean S.D. Mean S.D. Mean S.D. Mean S.D.
Panel B. Measures of air quality in mainland China, con't
SO2_China Concentration of sulfur dioxide (ppb). 2.61 0.98 2.03 0.44 1.84 0.59 3.20 0.87 2.79 0.96 0.21 7.7 %
NO2_China Concentration of nitrogen dioxide (ppb). 9.01 3.96 9.64 3.04 7.80 4.61 10.94 3.95 8.83 3.56 0.27 3.1 %
PM10_China Concentration of particular matter <10 (ug/m3). 49.84 22.96 39.34 13.17 36.99 18.55 53.42 24.08 54.63 22.78 −3.55 −6.5 %
PM2.5_China Concentration of particular matter <2.5 (ug/m3). 27.40 12.05 23.17 9.94 23.06 12.26 28.64 13.01 29.07 11.38 −0.54 −1.9 %
Panel C. Other explanatory variables in the air quality dataset
COVID-19 (0/1) If 1/22/20 - 3/31/20 (0/1). 0.07 0.26 0 0 0.36 0.48 0 0 0 0 – –
COVID-19 cases Daily cumulative number of COVID-19 cases. 0.24 1.04 0 0 1.15 2.05 0 0 0 0 – –
Visitors No. of daily inbound visitors (100,000 person). 1.26 0.45 1.48 0.13 0.58 0.55 1.34 0.15 1.47 0.17 −1.03 −70.1 %
Wind Wind speed in district (km/hour). 2.37 1.40 2.38 1.36 2.19 1.32 2.52 1.46 2.39 1.41 −0.06 −2.5 %
Coal Coal use (1 million mt/day). 0.07 0.01 0.05 0.00 0.06 0.00 0.07 0.00 0.07 0.01 0.01 14.4 %
Area District area (km2). 39.20 31.22 40.20 30.95 40.23 30.89 38.65 31.05 38.87 31.43 −0.18 −0.5 %
Population District population density (10,000 person/km2). 1.33 1.12 1.27 1.12 1.27 1.11 1.34 1.13 1.35 1.13 −0.01 −0.7 %
Rainfall Rainfall in district (mm/hour). 0.69 1.26 0.62 0.70 0.75 1.77 0.75 1.14 0.64 1.07 0.23 36.3 %
Non-working day Weekend day or holiday (0/1). 0.36 0.48 0.34 0.47 0.37 0.48 0.34 0.47 0.36 0.48 0.02 5.9 %
NꞏT 5741 354 1190 932 3265

Note: The sample period is January 1 - March 31 in each year.

a

Drawn from the air quality dataset.

b

Drawn from the motor vehicle traffic dataset (see Table A5).

c

Drawn from the metro use dataset (see Table A7).

d

Drawn from the U-bike rental dataset (see Table A8).