Changes to city's air pollution alert system

Shanghai's adjusted four-tier air pollution alert system, which lowered the criteria for alarm activation, was formally introduced by the environment authority yesterday.
SHINE

Shanghai's adjusted four-tier air pollution alert system, which lowered the criteria for alarm activation, was formally introduced by the environment authority yesterday.

Under the new criteria, the lowest blue alarm will be activated when both slight pollution (Air Quality Index reading between 101 and 150) and short-term heavy pollution (AQI over 200) are forecast for the coming 24 hours. Previously, a blue alarm was issued when moderate pollution (AQI between 151 and 200), and short-term heavy pollution were predicted for the following 24 hours.

The second-level yellow alarm will be triggered when the AQI is forecast for between 201 and 300 during the coming 24 hours, down from the previous 48 hours.

An orange alarm will be issued when the AQI is predicted for between 301 and 400, indicating severe pollution, over the coming 24 hours, or between 201 and 300 in the coming two days — down from three days previously.

The criteria for the highest-level red alarm remains unchanged. It will be activated when the AQI is forecast to top 400 in the following 24 hours.

Each alarm involves specific measures, like how often construction sites and streets shall be washed. The list of the industrial companies that should suspend operations or control waste discharge under the alarms has also been adjusted.

The Shanghai Environmental Protection Bureau said the lowered criteria might lead to more frequent activation of the alarms, but this doesn’t mean Shanghai’s air quality is getting worse.


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