Clouded Judgment? Air Pollution, Cognition, and Invalid Voting
With Diego Martin and Dario Salcedo
Abstract
Air pollution impairs cognition, and voting is a cognitively demanding task, yet the link between the two has received little attention. Using mayoral elections in Bogotá and an instrument based on election-day wind blowing from the diesel corridors of the TransMilenio bus system, we estimate the effect of exposure to pollution on invalid voting. A one-standard-deviation increase in NOx during voting hours raises the share of invalid votes by 0.7 percentage points on average. This effect is concentrated among older voters, for whom it reaches 1.3 points, and is absent among younger ones. Turnout does not mediate this effect. Placebos varying the timing, direction, and pollutant of the instrument confirm that the effect arises only when wind carries pollution toward voters. Decomposing the ballot reveals a single cognitive shock with two sides: on the simple mayoral ballot, pollution increases blank votes, while on the more complex city-council ballot, it increases spoiled votes. These results identify a cognitive channel through which environmental conditions shape elections, distinct from the emotional and turnout channels documented in prior work, and suggest that air quality shapes the accuracy with which citizens, especially vulnerable ones, record their preferences.