Capital answers pollution questions

Beijing issued a red alert for air pollution that took effect at 7 am on Tuesday and will remain in force until noon on Thursday. The Beijing Environmental Protection Bureau and the Beijing Environment Monitoring Center have answered some of the public's questions.

Q. The red alert was issued only 13 hours before it took effect, instead of 24 hours in advance. Why?

A: Under the capital's updated emergency response plan on air pollution, released in March, Beijing has to issue a red alert 24 hours before it comes into effect.

However, we first issued an orange alert, second to red, 31 hours in advance and then upgraded it to the highest level, red, which is in compliance with the regulation.

Q: Why has Beijing issued a red alert, considering it will last less than three days after taking effect?

A: Based on the updated emergency response system, the government can issue a red alert if severe air pollution is forecast to last for at least three days.

On Saturday, Beijing issued the orange alert, as severe air pollution was coming. Then the weather and environmental protection bureaus in Beijing, and its neighbors Tianjin and Hebei, got more detailed, accurate information on the smog on Monday saying the air quality would deteriorate gradually, with the pollution peaking on Tuesday and Wednesday.

The severe air pollution is forecast to last for 84 hours from midnight on Monday to Thursday at noon, meeting the terms of the regulation. So, Beijing upgraded to the red alert.

Q: When will the smog reach its peak?

A: From noon on Monday, the temperature inversion intensified, keeping the pollutants near ground level and making them harder to disperse. The smog would reach a peak on Tuesday and Wednesday. Southern areas would have the most severe air pollution in the capital.

Beijing will give timely updates to the public on the smog situation.

Q: Why was no red alert declared during the most severe smog the capital experienced this year, from Nov 27 to Dec 1?

A: Beijing issued an orange alert at 2 pm on Nov 27 through Dec 1, lasting for 106 hours, to curb the air pollution. No red alert was issued because the duration of the severe smog lasted for less than 72 hours, failing to meet the regulation.

From the afternoon of Nov 29 to early morning on Nov 30, a weak cold front improved the air quality, reducing the pollution from severe, thus breaking the severe smog's duration.

Q: What's the difference between the current smog situation and the earlier one considered the worst this year in the capital?

A: The current smog is forecast to not be as severe as the recent event from Nov 27 to Dec 1. But the current air pollution is expected to last for four days, until noon on Thursday, and to cover a broader area. Besides, the government has more detailed information and has taken tougher measures earlier to control emissions this time.