Ozone in the Royal Borough

Monitoring

Ozone is monitored using ultra violet absorption spectrophotometry. The concentration of ozone is determined by the amount of light absorbed at a wavelength of 254 nanometres. It is monitored at one site in the Borough at the North Kensington monitoring station.

You can get the latest readings and or historical data for the North Kensington site at www.airquality.co.uk

Long term trends

Ozone is monitored at one location in the Borough; some additional central London monitoring locations are included for comparative purposes.

annual mean levels have shown an overall increase at North Kensington, Bloomsbury and Marylebone Road
levels are higher at background locations when compared to roadside locations.

Annual mean ozone levels

Annual mean ozone levels - micrograms/cubic metre (mg/m³)
Year	North Kensington	Marylebone Road	Bloomsbury
1995	33		21
1996	30		19
1997	26	12	19
1998	31	12	21
1999	35	13	24
2000	33	13	22
2001	36	15	24
2002	32	14	22
2003	37	16	23
2004	36	15	24

The objective set by government is that the maximum 8 hour level should not be exceeded more than 10 times. This objective was breached in 1996, 1999, 2001, 2003 and 2004 since monitoring began in 1995. This corresponds to years with high hot summers.

Number of periods above the ozone 8 hour objective at North Kensington monitoring station

Number of periods above the ozone 8 hour objective at North Kensington monitoring station
Year	North Kensington
1995	5
1996	16
1997	10
1998	7
1999	24
2000	7
2001	12
2002	7
2003	29
2004	18

For information on the sources and health effects of ozone pollution go to Sources and health effects of air pollution