Table 1 | PM2.5 annual concentrations..

Year	Pedregal		Xalostoc
Year	Mean	SD	Mean	SD
1997	21.6	16.6	71.3	34.1
1998	29.3	16.8	64.9	25.4
1999	24.4	9.2	71	26.6
2000	24.7	11.3	54.8	25.3
2001	23.6	10.1	41.1	17.2
2002	23.1	9.7	38	13.7
2003	23.4	11.3	41.8	14.4
2004	18.4	9.4	35.5	14.7
2005	20.9	11.5	30.4	17.1
2006	17.8	8.4	29.8	15.6
2007	16.2	8.5	25.3	11.3
2008	18	8.3	26.3	10
2009	18.4	8.7	26.4	10.7
2010	14.4	7.4	24.9	13.2
2011	16.7	8.3	24.7	11.5
2012	17	7.5	25.9	11.7

Table 1: PM_2.5 annual concentrations in μg/m³ for North and South Metropolitan Mexico City area selected monitoring stations.