| Year |
Mean (DU) |
Max. ozone in DU (stations) |
Month (maximum) |
Min. ozone in DU (stations) |
Month (minimum) |
% variability |
| 1998 |
258.925 |
276.7 (Kano & Maiduguri) |
August |
235.6 (Calabar & PH) |
January |
14.85 |
| 1999 |
265.877 |
279.2 (Kano) |
June |
242.8 (Kano) |
January |
13.04 |
| 2000 |
263.813 |
281.9 (Maiduguri) |
May |
242.7 (Calabar & PH) |
December |
13.91 |
| 2001 |
263.079 |
281.9 (Kano) |
May |
243.1 (Calabar & PH) |
January |
13.74 |
| 2002 |
262.462 |
276.8 (Kano) |
June |
243.2 (Kano) |
January |
12.14 |
| 2003 |
260.079 |
280.4 (Kano) |
May/June |
243.0 (PH & Calabar) |
January |
13.34 |
| 2004 |
263.476 |
281.1 (Kano) |
June |
238.9 (Kano & Maiduguri) |
January |
15.01 |
| 2005 |
257.836 |
274.3 (Kano) |
May |
240 (Kano) |
December |
12.50 |
| 2006 |
262.469 |
280.5 (Kano) |
July |
238.3 (Kano & Maiduguri) |
January |
15.05 |
| 2007 |
257.954 |
275.0 (Kano) |
May |
241.3 (Calabar) |
January |
12.26 |
| 2008 |
263.881 |
278.8 (Kano & Maiduguri) |
July |
238.3 (Maiduguri) |
January |
14.53 |
| 2009 |
259.668 |
276.2 (Kano) |
May |
237 (Calabar & PH) |
December |
14.19 |
| 2010 |
260.419 |
274.7 (Kano) |
July |
237 (Calabar & PH) |
January |
13.72 |
| 2011 |
262.249 |
275.1 (Kano) |
May |
248.3 (PH) |
December |
9.74 |
| 2012 |
260.804 |
283.8 (Kano) |
May |
238.5 (Kano & Maiduguri) |
December |
15.96 |