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

Year	Months Present	Minimum	Median	Mean	90th Percentile	Maximum	Standard Deviation	Number of Observations	Detection Limit
2024		0.435	0.435	*	3.0	3.6	1.04	13	0.87
2023		0.65	1.6	1.70	3.5	3.9	1.07	26	1.3
2022		0.65	0.65	1.52	2.8	6.7	1.43	31	1.3
2021		0.65	0.65	*	1.9	4.8	0.95	23	1.3
2020		0.65	*	*	*	4.2	1.37	9	1.3
2019		0.65	1.9	2.00	3.4	7.5	1.57	29	1.3
2018		0.65	1.4	1.87	3.7	7.3	1.68	30	1.3
2017		0.65	1.5	2.00	3.2	6.6	1.46	28	1.3
2016		0.65	1.5	1.59	3.4	5.0	1.16	30	1.3
2015		0.65	1.5	1.56	2.6	3.5	0.84	30	1.3
2014		0.75	0.75	1.30	2.5	4.6	0.90	30	1.5
2013		0.75	0.75	*	2.1	2.5	0.53	28	1.5
2012		0.75	0.75	0.86	0.75	1.9	0.35	30	1.5
2011		0.75	0.75	0.84	0.75	3.2	0.48	29	1.5
2010		0.75	0.75	*	2.4	25	4.68	27	1.5
2009		0.75	0.75	0.75	0.75	0.75	0.00	31	1.5
2008		*	*	*	*	*	*	0	*
2007		0.75	0.75	*	2.7	8.9	1.75	26	1.5
2006		*	*	*	*	*	*	0	*
2005		*	*	*	*	*	*	0	*
2004		*	*	*	*	*	*	0	*
2003		5.0	*	*	*	8.0	1.05	6	2.0
2002		1	3.5	3.93	7.1	11	2.52	30	2.0
2001		1	3.0	3.60	7.0	12	3.10	31	2.0
2000		1	3.0	*	5.2	8.0	1.81	19	2.0
1999		1	2.0	*	4.1	5.0	1.39	20	2.0
1998		1	1	1.86	3.5	8.0	1.66	26	2.0
1997		1	1	2.11	5.3	11	2.40	28	2.0
1996		1	1	2.33	4.0	7.0	1.58	26	2.0
1995		1	1	1.88	4.0	5.0	1.35	30	2.0
1994		1	1	1.83	3.1	6.0	1.38	30	2.0
1993		1	2.0	2.58	5.0	7.0	1.74	27	2.0
1992		1	1	*	3.0	5.0	1.20	16	2.0
1991		1	1	*	4.0	7.0	1.84	25	2.0
1990		1	3.0	*	4.7	5.0	1.33	14	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.