Table 2 Changes to particle and ozone concentrations associated with variation in the gasoline-ethanol fuel mix

Column number:	(1)	(2)	(3)	(4)	(5)
Dependent variable:	BC	PM2.5	PM 100–800 nm	UFP 7–100 nm	Ozone
Unit:	µg m⁻³	µg m⁻³	cm⁻³	cm⁻³	µg m⁻³
Mean over hour window:	08:00	24-h	08:00	08:00	12:00–16:00
Sample period:	Oct/2010 to Apr/2011	Nov/2008 to	Jan/2011 to	Jan/2011 to	Nov/2008 to
	& Oct to Nov/2012	May/2013	May/2011	May/2011	May/2013
Number of sampling sites:	1	3	1	1	12
Source:	Own	CETESB	Own	Own	CETESB
Share of Gasoline E20/E25 in the flex fleet rises from 30 to 80%	−0.3 ± 1.9	0.2 ± 3.9	−1,249 ± 1,669	8,713 ± 4,559	−8.3 ± 5.0
Equivalently, share of Ethanol E100 in the flex fleet falls from 70 to 20%
Control variables (to correct for the influence of other determinants of particles)
Site-specific linear trend	Yes	Yes	Yes	Yes	Yes
Week-of-year fixed effects	No	Yes	No	No	Yes
Day-of-week fixed effects	Yes	Yes	Yes	Yes	Yes
Radiation (+100 W m⁻²)	0.5 ± 0.7	−0.4 ± 2.2	4 ± 825	235 ± 1,798	4.2 ± 0.7
Temperature (+1 ^oC)	0.0 ± 0.2	1.2 ± 0.5	236 ± 235	−847 ± 836	3.1 ± 0.4
Humidity (+10%)	0.1 ± 0.7	−1.0 ± 1.6	349 ± 721	−1,020 ± 1,712	−4.9 ± 1.3
Wind speed (+1 m s⁻¹)	−3.2 ± 1.2	−6.5 ± 2.8	−2,102 ± 1,410	−4,217 ± 3,489	−13.2 ± 2.1
Other meteorological and road traffic conditions (see notes)	Yes	Yes	Yes	Yes	Yes
R ²	62.0%	73.4%	76.0%	69.8%	70.7%
Number of observations	129	511	80	80	13,203
Number of regressors	18	74	19	19	96
Mean value of dependent variable	6.0	13.8	3,577	18,659	72.2

Coefficients and 95% confidence intervals, i.e., point estimate ± 2 standard errors. An observation is a date (columns 1, 3, 4) or a date-site pair (columns 2, 5). Samples exclude the colder months of June to September, and include all days of the week (columns 2, 5) or non-holiday weekdays only (columns 1, 3, 4). Radiation, temperature, humidity, and wind speed in the recorded unit. All columns additionally include several precipitation, thermal inversion and road traffic congestion indicators. Columns 1 to 4 further control for wind direction and column 5 follows Supplementary Table 4. Since the longer samples encompass 2010, columns 2, 5 include site-specific intercepts indicating the opening of the Greater São Paulo beltway’s southern section on March 31, 2010. The effect of raising the gasoline share in the flex fleet is scaled for in-sample variation from 30 to 80%. The corresponding variation in the ethanol share is one minus variation in the gasoline share. Ordinary Least Squares (OLS) estimates, with standard errors calculated by bootstrapping (200 samples each): (i) the consumer-level fuel choice data, to account for sampling variation in the predicted gasoline share in a first-step consumer demand model, and (ii) the pollutant-meterology-traffic data in the second-step particle regression, clustering by date

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