The conditions are correlated with the changing seasons so it's only logical to consider things on the other side of the equator. I suspect that all the effects

The conditions are correlated with the changing seasons so it's only logical to consider things on the other side of the equator. I suspect that all the effects will be gone around the equator where the differences between the months are quite small. I'm not sure about the city connections but I think there have been studies showing people in big cities suffer from more asthma and so on.