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	Annual Toxics Summary Concord-2975 Treat Blvd FAQs Silicon nanograms per cubic meter

Year	Months Present	Minimum	Median	Mean	90th Percentile	Maximum	Standard Deviation	Number of Observations	Detection Limit
2025		*	*	*	*	*	*	0	*
2024		*	*	*	*	*	*	0	*
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		*	*	*	*	*	*	0	*
2002		*	*	*	*	*	*	0	*
2001		*	*	*	*	*	*	0	*
2000		180	*	*	*	2500	1000	4	3
1999		630	1600	1950	3200	9100	1670	27	3
1998		67	1000	*	2300	2700	760	19	3
1997		570	1700	*	2600	5300	1110	22	3
1996		450	1700	1780	4000	5500	1390	26	3
1995		180	1600	2900	6800	19000	3850	27	3
1994		200	1900	1880	3500	3900	1090	29	3
1993		230	1500	2300	4800	7900	1840	27	3
1992		500	1800	*	2300	2600	638	22	3
1991		530	2100	2470	4100	7000	1530	27	3
1990		480	2000	*	4600	6200	1670	16	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.