BEIJING - Even for a city used to polluted winters, this month has been awful for Beijing.
The first day of December was marked by PM2.5 levels soaring to 634 micrograms per cubic metre, more than 25 times above the safe limit mandated by the World Health Organisation.
Air was hazardous for long stretches in the following two weeks. It was the worst pollution the city had suffered in more than a year.
But you don't have to cite numbers to Beijing's residents. After living here for a while, you will know what hazardous air looks and feels like.
Can't see the building across the road? Check. Have to turn on the lights during the day? Check. Coughing? Throat dry all the time? Double check.
What is hazy for folks living in the capital is the criteria behind the system of pollution alerts instituted by the government in 2013.
The red alert issued last Monday (Dec 7) was Beijing's first ever. Red is the highest level in a four-tier system which triggers emergency measures such as driving restrictions and factory closures.
But locals were left scratching their heads.
Just a week earlier, when pollution was worse, authorities kept the alert level at orange, the second-highest level. The apparent refusal to upgrade it to red upset many people.
The question on everyone's mind was: Why issue a red alert when the air quality index (AQI) was below 300, but only an orange one when AQI went beyond 500?
Authorities were forced to defend their red alert call on the day it was issued, saying that these statuses are based on duration and not severity.
Environment officials said heavy pollution has to be forecast for three days for a red alert to be issued. The most recent bout of bad air to hit Beijing was expected to last from Dec 8 to 10 and hence fit the criteria, unlike the earlier spell.
But the answer did not appease critics, who pointed out that firstly, the earlier spell had in fact lasted close to five days, from Nov 27 to Dec 1.
They also noted that since the red alert would expire at noon last Thursday, the forecast pollution did not actually meet the full three-day criteria of 72 hours.
This prompted another statement from the environmental agency. It insisted that the 72-hour critieria for red alert was met, because the spell of pollution actually began on Dec 7, not Dec 8.
Indeed, authorities had first issued an orange alert saying that smog would hit the city on Dec 7, before upgrading it to a red alert. So the whole period must be considered together, it said.
It is unclear why they did not specify this in their earlier statement.
As for the five-day spell which saw AQI levels go beyond 500, the agency said that there were two days in between when the pollution was not that heavy, hence it could not have issued a red alert then.
It was all rather confusing and unconvincing. The alert statuses seemed as if they were issued piecemeal, with justifications shaped to fit a decision.
To the average person, the earlier spell of pollution this month was undoubtedly worse than the one last week. While pollution levels were hazardous last week, these were readings that have been seen in Beijing throughout this year.
One also has to question if it makes sense to issue alert statuses on the basis of duration and not severity - surely both factors are at least equally important?
A more refined system is needed because the alerts trigger measures that can wreak havoc on people's routines. When the red alert was issued on Monday evening, parents had to scramble to look for caregivers for their children, as schools were urged to close the following day.
And because half the private cars in Beijing were ordered off the roads, the public transport network was strained.
Netizens did not buy this "better late than never" red alert move, with many speculating online that it was a knee-jerk reaction by politicians.
The government has cause to worry because Beijing residents have, with rising affluence, become intolerant of the choking smog they and their children have to put up with.
Although the local government in Beijing thanked the public for their understanding and cooperation during the red alert period, Chinese reports say more locals are choosing to leave the city - either temporarily or permanently - when serious smog hits.
There is also a widespread belief that the government - despite pledges to curb emissions - is closing an eye to polluting factories that surround Beijing.
The authorities can try to repair their credibility by refining their pollution alert statuses to be more rigorous and sensible.
Given that we are at the start of winter - typically Beijing's most polluted season - the opportunity for doing so should be coming up very soon.