Politicians use less complex speech on polluted days. "We apply textual analysis to convert over 100,000 verbal statements made by Canadian MPs from 2006 through 2011 into—among other metrics—speech-specific Flesch-Kincaid grade-level indices. This index measures the complexity of an MP’s speech by the number of years of education needed to accurately understand it. Conditioning on individual fixed effects and other controls, we show that elevated levels of airborne fine particulate matter reduce the complexity of MPs’s speeches. A high-pollution day, defined as daily average PM2.5 concentrations greater than 15 µg/m³, causes a 2.3% reduction in same-day speech quality. To put this into perspective, this is equivalent to the removal of 2.6 months of education." Heyes et al 2019.