These winter blue days must not be taken for granted

SO FAR THIS WINTER, the masks that used to be a common sight at this time of year have been less evident as the number of days with blue skies in Beijing and its surrounding regions has been much higher than in the recent past. China Youth Daily comments:

It is good news that we can enjoy the blue winter sky in Beijing. It is even better news to see breathing masks and air cleaners, once deemed necessities for residents in Beijing, are losing their appeal.

That's why some media outlets have been hailing the improvement in Beijing's air quality. However, it is still too early to celebrate because the improvement has multiple causes, including natural conditions.