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	Annual Toxics Summary San Francisco-Arkansas Street FAQs Silicon nanograms per cubic meter

Year	Months Present	Minimum	Median	Mean	90th Percentile	Maximum	Standard Deviation	Number of Observations	Detection Limit
2023		*	*	*	*	*	*	0	*
2022		*	*	*	*	*	*	0	*
2021		*	*	*	*	*	*	0	*
2020		*	*	*	*	*	*	0	*
2019		*	*	*	*	*	*	0	*
2018		*	*	*	*	*	*	0	*
2017		*	*	*	*	*	*	0	*
2016		*	*	*	*	*	*	0	*
2015		*	*	*	*	*	*	0	*
2014		*	*	*	*	*	*	0	*
2013		*	*	*	*	*	*	0	*
2012		*	*	*	*	*	*	0	*
2011		*	*	*	*	*	*	0	*
2010		*	*	*	*	*	*	0	*
2009		*	*	*	*	*	*	0	*
2008		*	*	*	*	*	*	0	*
2007		*	*	*	*	*	*	0	*
2006		*	*	*	*	*	*	0	*
2005		*	*	*	*	*	*	0	*
2004		*	*	*	*	*	*	0	*
2003		1400	*	*	*	4500	1140	6	2
2002		270	1600	2200	4500	9000	1860	30	2
2001		320	1300	2200	5800	7200	1920	31	3
2000		600	2100	*	5300	5700	1800	19	3
1999		400	1500	*	2900	3200	791	20	3
1998		340	1300	1440	2700	3800	855	26	3
1997		250	1400	1860	3900	6700	1510	28	3
1996		130	1400	2110	3700	7100	1700	26	3
1995		200	1600	1950	4200	6800	1710	30	3
1994		180	1400	1920	4600	8500	1810	30	3
1993		240	1400	2360	4700	7300	1780	27	3
1992		470	1300	*	2700	3800	968	16	3
1991		550	1700	*	3900	12000	2490	25	3
1990		400	1600	*	3700	5800	1500	14	3
1989		*	*	*	*	*	*	0	*

	Notes:	Values below the Limit of Detection (LoD) assumed to be ½ LoD. Means and risks shown only for years with data in all 12 months. "*" means there was insufficient or no data available to determine the value.