seasonal

There isn't a single cause behind the problem, but a mix of factors like low wind speeds, industrial emissions, vehicle exhaust, dropping temperatures and the seasonal burning of crop stubble in neighbouring states.

Every year, hundreds of thousands of U.S. workers take on seasonal jobs during the holidays.

Earlier this month, the seasonal effect was neutered by stock-market weakness.

It said the data was not directly comparable to annual figures, with the possibility of seasonal effects on releases and late recordings.

Recent U.S. data are undermining the crude excess story, with even last week’s big stock build in line with seasonal patterns, he says.