The first full day back at work/school, combined with the tightening of the national daily air quality index four days ago, resulted in nitrogen dioxide being recorded as ‘high’ this morning on Putney High Street. The lower index thresholds now in force are likely to mean that this will now be a more common occurrence. This morning’s peak of 468 ugm-3, now an index level 8 (high), would previously have been classified as index level 6 (moderate).
The new air quality index came into force on 1st January with tighter thresholds reflecting increasing concern by health experts as to the adverse effects of exposure to air pollution. The high banding threshold for nitrogen dioxide is now at 400ugm-3 as an hourly mean, compared to 573 ugm-3 previously.

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Item date 04/01/2012 12:00:00