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8. B. - Page 182 I�� calcL�lating the 70 year exposL�re dose atid ca��cer rislc, sta�ldard BAAQIVID methods are used�. As discussed in the Final EIR (Response 0-41, page 62), the BAAQNID Health Risk Screeiung Analysis (HRSA) gL�idelines specify that "where a su�gle ca��cer risk value for a residential receptor is needed or pn�dent for risk ma�7agement decision-mal�ing, the potential ca�lcer rislc estimate for the inhalation exposure pathway be based on the breathulg representing the gp percentile valL�e of the breatlung rate ra�lge of values (302 Ukg-day)". Thus, using BAAQMD methods, the 70 year exposL�re dose shoL�ld be calculated using the 80 percentile value of the breathing rate. Had BAAQIVID intended to use child breathing rates for the first 16 years of exposure in the yea�-by-year calculations described above, the child breatlung rate would have been incoiporated u�to the calculations for the a�u�ual SWF weighted emission rate for each of the first 16 years and the adi�lt breathulg rate for the remainder of the 70 year period. As noted above, however, the 70 year exposure dose is calculated usu7g the 8p percentile vali�e of the adult breathing rate over the entire 70 year period. For the City's a��alysis of cancer rislcs from roadways, a simplified calcl�lation was L�sed that is consistent with the BAAQMD inethod which overestiinates the potential ca�lcer risks. Specifically, r«tlier tliafi c�aleul�ite ro«�liv«y TAC emissions for each ye«r over « 70 year perio�l, efyiissions ivere c�cicul�ate�l by the City for fou� ficture ye�ars ivitliin the 70 ye�a� perio�l (201=1, 201�, 2020, afi�1202�). Emissions for 2014 were used to represent the enussions during 2014, enussions for 2015 were used to represent enussions during the period from 2015 to 2019, enussions for 2020 were used to represent enussions during the period from 2020 to 2024, a��d enussions from 2025 were used to represent enussions from 2025 L�ntil the end of the 70 year period. These enussions for each time period were then used ul the air dispersion model, along with the estimated traffic volumes, to calculate a�erage TAC concentrations over fl�e periods of time represented by the enussions calculations. These concentrations were then used to calcL�late exposure doses for each time period, which were then mi�ltiplied by the period-specific SWFs, and the ca�lcer potency factor to obtain the ca�lcer rislc contribution for each period. Ca�lcer risks from each time period were then sununed to obtain a total 70 year ca�lcer rislc. Since vehicle einissions, particL�larly from diesel vehicles, a�e expected to decrease fromyear to year in the futl�re, use of these periodic enussions will overestimate the actual average enussions during the period between the years with calculated enussions. For example, in the City's calculations for the contribL�tion to the total 70 yea� ca�lcer risk between 2015 and 2019, the emission rate froin 2015 was nsed to represent the einissions for eveiy year in this period. Whereas, it is expected that the actual emissions, if calculated on a year-by-year basis during tlus time period, would decrease between 2015 a��d 2019 rather than be constant at the 2015 level as assLUlled by the City and the associated ca�lcer risks for this time period woL�ld actually be lower tha�1 what was reported by the City. Therefore, the City i�sed a conservative approach that is consistent with the BAAQMD methods, but likely resL�lts in an overall higher estimate of potential ca��cer risks tha�� if the calculations were performed on a yea�-by-year basis. ' BAAQNID. 2011. Recommended Methods for Screeiuna and Modelin� Local Risks and Hazards. Bay Area Air Qualin-• Management Disriict. Ma��, 2011, page 88. � BAAQNID. 2010. BAAQNID Air To�ics NSR Pro�am, Health Risl� Screeiun� Ai�l��sis (HSRA) Guidelines. Ba� Area Air Qt�alin- Management District January, 2010, page 2. 2580 El Cainino Real Residenrial Project 1� Response to Conmients Recei��ed on Final EIR Cin� of Red��ood Cin� Jannai� 2012