On 14 August 2003, 50 million people were left without light for 30 hours in the US and Canada.
Researchers have now published the data collected in the low atmosphere on August 15 and the conclusions are surprising. For example, air pollution decreased much more than expected: ozone concentration decreased by half, sulfur dioxide decreased by 90% and the typical fog of the Pennsylvania area disappeared.
Therefore, even though the blackout made the night even blacker, during the day the light increased. In fact, visibility in some places was 40 km higher than otherwise.