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	Annual Toxics Summary Concord-2975 Treat Blvd FAQs Zirconium 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		*	*	*	*	*	*	0	*
2002		*	*	*	*	*	*	0	*
2001		*	*	*	*	*	*	0	*
2000		1	*	*	*	4.0	1.50	4	2.0
1999		1	2.0	1.97	3.0	7.0	1.33	27	2.0
1998		1	1	*	3.0	4.0	1.05	19	2.0
1997		1	1	*	2.8	5.0	1.10	22	2.0
1996		1	1	1.85	4.0	5.0	1.26	26	2.0
1995		1	1	1.71	3.4	5.0	1.27	27	2.0
1994		1	1	1.57	3.0	6.0	1.23	29	2.0
1993		1	2.0	2.92	5.0	16	3.06	27	2.0
1992		1	1	*	2.0	3.0	0.65	22	2.0
1991		1	2.0	2.26	4.0	5.0	1.24	27	2.0
1990		1	1	*	4.5	6.0	1.60	16	2.0
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.