CDKN2A and acute lymphoblastic leukemia: With the exception of ALL with IKZF1 deletion, these observations appeared to be driven mostly by the population characteristics, PM2.5 burden, and ozone burden, with statistically (or closely) significant HRs equal to 5.11, 2.68, and 2.59, respectively for high-hyperdiploidy negative ALL, and HRs for ALL with CDKN2A deletion equal to 3.56 for PM2.5 and 2.52 for ozone.