With fewer people getting cold and therefore less of the common cold going around even some people who don't eat Booming Berries or produce the berries will benefit from not getting sick. So, from an economics perspective, the market for Booming Berries has an impact on people who do not buy or sell the berries. That is correct; the market for Booming Berries contains a: 1) Negative externality 2) Positive externality