Wow. That paper made no effort to even contemplate whether the improvement was related to reduced particulate matter or to reduced organic gasses. The filters

Wow. That paper made no effort to even contemplate whether the improvement was related to reduced particulate matter or to reduced organic gasses. The filters were installed in response to a gas leak — one would imagine they were carbon filters. Sadly, the literature on the effect of gas concentrations on human intellectual function is incredibly muddy.