Patents, Pollution, and Pot

In recent years, new research has significantly increased my belief that air pollution has substantial negative effects on productivity, IQ and health (see previous posts). Research in the field is exploding which means that there must also be more false positives. Consider two recent papers. The first, The Real Effect of Smoking Bans: Evidence from Corporate Innovation by Gao et al. finds that smoking prohibition increased patenting!

We identify a positive causal effect of healthy working environments on corporate innovation, using the staggered passage of U.S. state-level laws that ban smoking in workplaces. We find a significant increase in patents and patent citations for firms headquartered in states that have adopted such laws relative to firms headquartered in states without such laws. The increase is more pronounced for firms in states with stronger enforcement of such laws and in states with weaker preexisting tobacco controls. We present suggestive evidence that smoke-free laws affect innovation by improving inventor health and productivity and by attracting more productive inventors.

But the second, Do Firms Get High? The Impact of Marijuana Legalization on Firm Performance, Corporate Innovation, and Entrepreneurial Activity by Wang et al. finds that marijuana legalization increased patenting!

We find that state-level marijuana legalization has a positive financial impact on firms, likely by affecting firms’ human capital. Firms headquartered in marijuana-legalizing states receive higher market valuations, earn higher abnormal stock returns, improve employee productivity, and increase innovation. Exploiting firm level inventor data, we directly test the human capital channel and find that post legalization, firms retain inventors that become more productive and recruit more innovative talents from out of state. We also find that marijuana-legalizing states experience an increase in the number of new startups and venture capital investments.

Would anyone have been surprised if these two papers had shown exactly the opposite results? Indeed, there is some evidence that nicotine is solid cognitive enhancer and Tyler recently argued, on the basis of good evidence, that pot makes people dumb. Is it a coincidence that anti-cigarette and pro-pot papers appear as the country moves in this direction? Social desirability bias also applies to research. So no knock on either paper but I am unconvinced. As I like to say, trust literatures not papers.

Hat tip: The excellent Kevin Lewis.


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