Ozone and childhood respiratory disease in three US cities: evaluation of effect measure modification by neighborhood socioeconomic status using a Bayesian hierarchical approach

Table 2 Summary of respiratory ED visits⁺ among 5–18 year-olds in Atlanta, Dallas, and St. Louis

	Complete ED Database (data from all ZCTAs)		Analytical ED Database (data from ZCTAs with ≥50 ED visits)
						ED visits per ZCTA
City	Number of ZCTAs	ED visit Number^a	Number of ZCTAs	ED visit Number^b	% of total ED visits^c	Min	Mean	Max
Atlanta	191	211 530	179	211 207	99.8%	54	1 180	4 883
Dallas	253	96 983	205	96 108	99.1%	51	469	2 237
St. Louis	256	113 285	151	111 949	98.8%	55	741	5 052

⁺primary diagnosis of respiratory disease (ICD-9 codes 460–486,493,786.07)
^atotal number of respiratory ED visits from all ZCTAs
^btotal number of respiratory ED visits from ZCTAs with ≥ 50 ED visits over the study period of each city
^c‘total ED visits’ are represented by the ED visit number from the ‘Complete ED Database’
Abbreviations: ED Emergency Department, ICD-9 International Classification of Diseases, 9th Revision, Max maximum, Min minimum, ZCTA Zip Code Tabulation Area

ISSN: 1476-069X