I concur in part III.B. of the majority opinion, which holds that the decision of the Regents of the University of California (hereafter Regents) not to recirculate the final environmental impact report (hereafter EIR) is subject to review under the substantial evidence standard, and in part III.C., subparts 2-5, which hold that substantial evidence supports the Regents’ decision not to recirculate the revised EIR on the basis of that document’s inclusion of new information regarding the proposed Laurel Heights facility’s toxic air emissions, loading docks, night-lighting glare, and project alternatives. (Maj. opn., ante, at pp. 1132-1135, 1137-1143.)
I respectfully dissent, however, from part III.A. of the majority opinion, interpreting Public Resources Code section 21092.1,1 and part III.C., subpart 1, analyzing whether substantial evidence supports the Regents’ decision not to recirculate the final EIR on the basis of that document’s inclusion of new information describing other attributes of the proposed facility, including its round-the-clock operations and the additional noise that this would generate.
In my view, the majority errs in holding that the addition of “significant new information” to an EIR requires recirculation of an EIR under section 21092.1 only where “the EIR is changed in a way that deprives the public of a meaningful opportunity to comment upon a substantial adverse environmental effect of the project or a feasible way to mitigate or avoid such an effect (including a feasible project alternative) that the project’s proponents have declined to implement.” (Maj. opn., ante, at p. 1129, original italics.) The majority’s specification of a “substantial adverse environmental effect” departs from the plain language of section 21092.1, which provides only that the inclusion of “significant new information” in an EIR suffices to require recirculation of that document for public comment. The majority’s unduly narrow interpretation is fundamentally at odds with the legislative intent and public policies underlying the California Environmental Quality Act (CEQA) (§ 21000 et seq.) as described in our decisions, cited post, next page.
*1144Furthermore, although I agree with the majority’s conclusion that the new information set forth in the final EIR relating to toxic air emissions, loading docks, night-lighting glare, and project alternatives does not rise to the level of “significant new information” within the meaning of section 21092.1, I agree with the Court of Appeal that the final EIR in other respects does contain “significant new information”—insofar as it discloses the Regents’ intention to conduct round-the-clock operations at the proposed Laurel Heights facility, resulting, among other effects, in an increase in noise. Accordingly, the Regents should have recirculated the final EIR for public comment.
The majority interprets section 21092.1 to refer only to new information that, in the opinion of the lead agency, describes or will produce “substantial adverse environmental effects.” Yet, this clearly is not what the statute commands.2 More accurately, section 21092.1 requires recirculation of an EIR when that document includes new information as to which additional public comment would (1) substantially advance the core informational purpose of the document, and (2) assist the lead agency in identifying potential significant adverse effects of the project, as well as alternatives and mitigation measures that substantially would reduce these effects. (See Citizens of Goleta Valley v. Board of Supervisors (1990) 52 Cal.3d 553, 564 [276 Cal.Rptr. 410, 801 P.2d 1161]; Laurel Heights Improvement Assn. v. Regents of the University of California (1988) 47 Cal.3d 376, 390-391 [253 Cal.Rptr. 426, 764 P.2d 278] [hereafter, Laurel Heights I]; No Oil, Inc. v. City of Los Angeles (1974) 13 Cal.3d 68, 79 [118 Cal.Rptr. 34, 529 P.2d 66]; Cal. Code Regs., tit. 14, §§ 15021, 15064, 15121, 15204.) In holding otherwise, the majority departs from the plain meaning of section 21092.1, the public policies underlying CEQA, and this court’s own admonition that the Legislature intended CEQA “ ‘to be interpreted in such manner as to afford the fullest possible protection to the environment within the reasonable scope of the statutory language.’ ” (Laurel Heights I, supra, 47 Cal.3d at p. 390, quoting Friends of Mammoth v. Board of Supervisors (1972) 8 Cal.3d 247, 259 [104 Cal.Rptr. 761, 502 P.2d 1049].)
The majority holds “it is appropriate to look to [section 21166 and its implementing guidelines] for guidance in interpreting section 21092.1.” (Maj. opn., ante, at p. 1129.) I believe, however, that the majority’s reliance *1145upon these sources is inappropriate. It is axiomatic that this court’s task in interpreting a statute is to ascertain the Legislature’s intent, turning first “to the words themselves for the answer,” giving effect to statutes “according to the usual, ordinary import of the language employed in framing them.” (Palos Verdes Faculty Assn. v. Palos Verdes Pennisula Unified Sch. Dist. (1978) 21 Cal.3d 650, 658 [147 Cal.Rptr. 359, 580 P.2d 1155], internal quotation marks omitted.) The majority ignores these fundamental rules, however, by interpreting section 21092.1 in a manner contrary to the statute’s actual language. “[Significant new information,” the phrase contained in section 21092.1, and “substantial adverse environmental effects,” the interpretation embraced by the majority, constitute distinct standards. The statutory standard of “significant new information” clearly is prospective and explanatory in nature, emphasizing the function of an EIR as an informational document prepared for the benefit of a concerned citizenry. (See Laurel Heights I, supra, 47 Cal.3d at p. 391 [the purpose of an EIR is to provide public agencies and the public in general with “detailed, information”].) The majority’s standard of “substantial adverse environmental effects,” in contrast, focuses upon anticipated results, requiring that new information set forth in a revised EIR suggest previously undisclosed and substantial environmental impacts, before recirculation is required. As aptly observed by the Court of Appeal in this case, had the Legislature intended that the standard for recirculation hinge upon an EIR’s inclusion of information describing significant new “impacts,” it easily could have said so.
In addition to finding unsupportable the majority’s statutory analysis, I believe the majority’s application of its analysis to the circumstances of the present case is seriously flawed in several respects.
The majority holds it was unnecessary for the Regents to recirculate the final EIR, because that document simply provides “additional noise data[,] . . . studies [that] merely serve to amplify, at the public’s request, the information found in the draft EIR.” (Maj. opn., ante, at pp. 1136-1137.) Yet, as I explain below, the majority’s emphasis on the purported insignificance of the additional noise data contained in the final EIR mischaracterizes the fundamental difference between that document and the draft EIR: the draft (nearly 900 pages in length, including appendices) includes only a few vague, inadequate references to the heightened activity anticipated at the proposed Laurel Heights project, yet the final EIR describes a facility, the major components of which would operate on a round-the-clock basis. In my view, this difference in the contents of the two documents is statutorily “significant” (§ 21092.1) and thus in itself warrants recirculation of the final EIR for public comment.
*1146The draft EIR in the present case describes a proposed facility that, not unlike typical commercial establishments (such as the insurance offices that previously occupied the site), would operate primarily during normal business hours. The draft EIR further states, rather vaguely, that “[t]he research use would likely result in more evening and weekend activity at the site than at present, although most occupants would probably leave by about 7 p.m.” The draft EIR also notes that the facility “would be used more heavily in evening hours and on weekends than at present . . . .” These two general comments constitute the draft EIR’s only references to the round-the-clock activity subsequently described in the revised EIR.
In contrast, the final EIR indicates that the biomedical research programs (slated to occupy approximately 80 percent of the 352,800-square-foot facility) actually would remain open and operating throughout the night, with concomitant increases in noise (from rooftop exhaust fans and increased traffic), and other effects. This new information, describing an environmental impact of great significance to residents in the Laurel Heights neighborhood, extends well beyond “simply clarif[ying], amplif[ying], or mak[ing] insignificant modifications to an adequate EIR.” (Marin Mun. Water Dist. v. KG Land California Corp. (1991) 235 Cal.App.3d 1652, 1667 [1 Cal.Rptr.2d 767].) Indeed, the final EIR—unlike the draft EIR—describes an all-night operation located in the heart of a “predominant[ly]” residential neighborhood. For this reason alone, the final EIR should have been recirculated.
The draft EIR further states that, in addition to the facility’s proposed occupancy of 1,530 persons, “[visitors associated with the proposed uses are projected to number about 340 people on an average daily basis.” The draft EIR estimates that the facility would generate an estimated “106-142 daily truck trips,” i.e., “an average of nine trucks an hour over an eight hour delivery day.” The draft EIR concludes that, “[intensification of activity at [the] Laurel Heights [facility] would not disrupt ... the existing physical community and would not constitute a major change to land use on site since the facility has been used with similar land use patterns for several decades.” The draft EIR characterizes the intensification of land uses at the Laurel Heights facility and increases in traffic-related activity as “not significant,” similarly characterizing the noise from exposed equipment, after mitigation measures are taken, as “not significant.” The clear implication of these (and other) passages contained in the draft EIR is that the proposed facility would not involve a significant change in activity or noise from that already associated with the site.
In this respect, the final EIR stands in stark contrast to the draft EIR, the final document stating: “[T]he facility for the most part would operate *1147between 6 a.m. and 10 p.m. However, laboratories would likely operate on a 24-hour basis on occasion when research activities so require .... [¶] In order to provide proper laboratory ventilation, rooftop mechanical equipment would likely run 24 hours per day.” (Italics added.) Implicit in statements contained in the final EIR is the circumstance that a certain number of laboratory workers, visitors, and delivery couriers would arrive and depart during that 24-hour period. This dissimilarity between the draft EIR and the final EIR, in their respective descriptions of the facility’s hours of activity, requires recirculation of the final EIR.3
The draft EIR, although lengthy, provides no information regarding the amount of noise that might be emitted from laboratory exhaust equipment (which the draft EIR describes as including 100 to 120 rooftop exhaust stacks, each one over 9 feet in height), nor does it contain any measurements of nighttime noise levels in the adjacent residential areas.4 Notwithstanding these important factual omissions, the draft EIR concludes: “It is unlikely that the noise from building equipment would be greater than the existing ambient noise levels.”5 In response to public comment regarding noise levels, the final EIR acknowledges that “[equipment noise would be considered significant if the noise levels created by the equipment exceeded 50 dBA . . .” (italics added), and modifies the draft EIR’s earlier conclusion to state as follows: “Noise from equipment installed on roofs or other exposed areas could generate noise levels above the ambient noise level and the 50 dBA standard [set forth] in the San Francisco Noise Ordinance.” (Italics added.) The final EIR thereafter states that, with the aid of various mitigation measures, the local noise ordinance limit of 50 dBA “could be met.” In view of the draft EIR’s woeful inadequacy in addressing the noise-level issue, and the only slightly more substantive analysis contained in the final EIR, the revised document should have been recirculated for this reason *1148alone. (See Mountain Lion Coalition v. Fish & Game Com. (1989) 214 Cal.App.3d 1043 [263 Cal.Rptr. 104] [where draft EIR inadequately addressed environmental consequences, circulation of a cumulative impact analysis for public comment was required].)6
The draft EIR states that the Laurel Heights facility “would cause only a slight increase over existing [traffic] volumes[, and] traffic-generated noise would not be significant.” The draft EIR further asserts (rather strangely) that “increased [traffic] noise would be generated[, h]owever, the noise increase would not be audible.”
The final EIR, while attempting to clarify the traffic-noise analysis, instead clouds the issue, the final document stating: “[P]roj ect-generated vehicle trips would not be sufficient to have a noticeable effect oh average noise levels along local roadways. However, it is acknowledged that individual short-term noise events, particularly from trucks, could be annoying to noise sensitive receptors.” By recasting vehicle noise as “short-term noise events” and concerned neighbors as “noise sensitive receptors,” the final EIR engages in an assault upon its readers’ linguistic sensibilities that parallels the project’s potential assault upon its neighbors’ auditory senses. The final EIR’s inadequate and obfuscatory analysis, although tolerated by the majority, clearly fails to satisfy the requirement that, once comments are received from the public, “ l[t]here must be good faith, reasoned analysis in response.’” (Sutter Sensible Planning, Inc. v. Board of Supervisors (1981) 122 Cal.App.3d 813, 820 [176 Cal.Rptr. 342], quoting Silva v. Lynn (1st Cir. 1973) 482 F.2d 1282, 1285, italics by the Sutter court; see also Mountain Lion Coalition v. Fish and Game Com., supra, 214 Cal.App.3d at p. 1051 [rejecting attempt “to circulate a document that simply swept the serious criticisms of the project under the rug”].)
Despite the draft EIR’s acknowledgement that the Laurel Heights project will demand 722 parking spaces and accommodate only 516, leaving “206 vehicles unaccommodated,” the final EIR blithely dismisses public concern regarding this issue: “Parking calculations concerning current and projected *1149parking demand are based on the project’s estimated on-site population, not on parking survey results. Parking occupancy near the site is thus not a factor in the analysis of project parking demand.” (Italics added.) This response, too, does not appear to constitute “good faith, reasoned analysis,” nor does it comply with this court’s prior admonition to the Regents that “significant cumulative effects of a project must be considered . . . .” (Laurel Heights I, supra, 47 Cal.3d at p. 394.) Instead, the final EIR acknowledges that parking in the Laurel Heights neighborhood is “saturated,” with a parking occupancy rate of “96-99%,” but fails to address meaningfully the environmental impact (i.e., the traffic noise or other inconvenience to neighborhood residents) of up to 206 vehicles traveling through the neighborhood, perhaps late at night or in the early hours of the morning, on a daily basis, as thpir drivers search for a parking place.
The majority finds solace in the Regents’ representations, contained in the final EIR, that they will adopt an array of procedures “to mitigate project noise to insignificant levels.” (Maj. opn., ante, at p. 1136, fn. 25.) I do not believe we should be so sanguine. A facility comprised of laboratories operating throughout the night, in contrast to operation during normal business hours, necessarily will cause its employees and at least some of its “340 [daily] visitors” to arrive and depart at odd hours, adding to traffic noise at times when most residents in the neighborhood are likely to be . asleep. The final EIR leaves unclear how, if at all, the Regents could reduce the increased nighttime traffic noise “to insignificant levels.”7
The majority opinion holds that the additional data pertaining to noise “merely serve to amplify, at the public’s request, the information found in the draft EIR.” (Maj. opn., ante, at p. 1137, italics added.) Having compared the draft EIR and the final EIR, I am unpersuaded by the majority’s holding; in my view, the latter document does more than “clarify” or “amplify” the former. Indeed, the final EIR includes precisely the type of “ ‘substantial changes’ ” that require recirculation. (See Sutter Sensible Planning, Inc. v. Board of Supervisors, supra, 122 Cal.App.3d at pp. 822-823, quoting State of Alaska v. Carter (D.Alaska 1978) 462 F.Supp. 1155, 1164.) Although the draft EIR appears to have suggested that the proposed Laurel Heights facility, similar to a typical commercial establishment, would operate primarily during daytime hours, the final EIR makes clear that significant
*1150Despite this “significant new information,” the majority holds that “substantial evidence” supports the Regents’ decision not to recirculate the final EIR. Having noted the draft EIR’s inadequate analysis of project-related noise and other features of the proposed facility, I believe the majority’s conclusion in this regard renders hollow and meaningless the term “substantial evidence.” As I have discussed above, the draft EIR was not “sufficient as an informational document” (.Laurel Heights I, supra, 47 Cal.3d at p. 407). Indeed, it was deficient in numerous respects, and the applicable legal standard, set forth in several decisions, prohibits project proponents from being permitted to “fill in” analytical gaps in a final EIR insulated from public comment. (See, e.g., Mountain Lion Coalition v. Fish & Game Com., supra, 214 Cal.App.3d at pp. 1050-1053; Sutter Sensible Planning, Inc. v. Board of Supervisors, supra, 122 Cal.App.3d at pp. 822-823.) In holding otherwise, the majority erroneously exalts the pro forma and misleading representations contained in the draft EIR over the substantive requirements of the law.
In view of the predominantly residential character of the neighborhood in question, I conclude that the final EIR’s determination that the proposed Laurel Heights facility likely would operate on a 24-hour basis constitutes “significant new information” within the meaning of section 21092.1, requiring that the Regents recirculate the final EIR.
Accordingly, I would affirm the judgment of the Court of Appeal, reversing the trial court’s order denying the Laurel Heights Improvement Association’s petition for a writ of mandate, and remanding the matter to the trial *1151court with instructions to issue a writ of mandate directing the Regents to recirculate the final EIR for public comment.8
Appellant’s petition for a rehearing was denied February 24, 1994, and the opinion was modified to read as printed above. George, J., was of the opinion that the petition should be granted.
All further statutory references are to the Public Resources Code.
Section 21092.1 provides in pertinent part: “When significant new information is added to an [EIR] after notice has been given pursuant to Section 21092 and consultation has occurred pursuant to Sections 21104 and 21153, but prior to certification, the public agency shall give notice again . . . and consult again . . . before certifying the [EIR].”
Neither the draft EIR, nor the final EIR, specifically designates what portion of the Laurel Heights facility is to be occupied by laboratories. The draft EIR, however, suggests that the portion devoted to such use would be quite considerable, stating that, of the 80 percent of the facility proposed for biomedical research, “70 [percent] is generally devoted to laboratories, special equipment, and other support areas, and office space for researchers (minimal).”
The draft EIR relied upon a measurement of noise levels during a single afternoon, between 3:40 p.m. and 5 p.m., then used this information to project the 24-hour average noise level in the surrounding residential areas. One need not be an acoustical expert to question the value of such an average, in view of the neighboring residents’ concerns having focused upon the proposed facility’s contribution to nighttime noise.
The Environmental Review Officer of the San Francisco Department of City Planning opined that the Regents’ conclusion regarding the “insignificance” of nighttime noise “has no visible means of support,” adding that “[i]t would be a good idea to reanalyze nighttime noise resulting from typical laboratory exhaust equipment to compare it with actual nighttime noise measurements in the area, in order to inform the nearby residents of potential noise.” (Italics added.)
Despite the public concern over the conclusory nature of the draft EIR’s noise analysis, the final EIR nevertheless adheres to certain highly questionable assumptions. For example, the final EIR states: “The mechanical noise could be detectable above the minimum background noise levels outdoors during the early morning hours, but would not be detectable indoors at any time.” Bearing in mind that the proposed Laurel Heights facility would be located directly across the street from single- and multi-family residential dwellings, the final EIR’s statement unreasonably assumes that neighbors never will open their windows.
In the present case, even if mitigation measures suggested by the Regents were to reduce project-related noise to 49 decibels, adjusted (dBA) (1 dBA below the limit allowable by local ordinance), I would not agree with the majority’s conclusion that such noise, which the final EIR (unlike the draft EIR) indicates might occur on a 24-hour basis, would not constitute “significant new information” within the meaning of section 21092.1. *1150portions of the facility, such as laboratories and associated rooftop mechanical equipment, would operate on a round-the-clock basis. Under these circumstances, the Laurel Heights Improvement Association’s request for recirculation of the final EIR was justified and should have been honored. In view of the “significant new information” (§ 21092.1) contained in the final EIR, I am unpersuaded by the Regents’ argument that the request constituted an attempt to subvert CEQA rules into an instrument of “oppression and delay.” (Citizens of Goleta Valley v. Board of Supervisors, supra, 52 Cal.3d at p. 576.)
The parties agree that recirculation would have lengthened the review process by a matter of a few months. At oral argument, the Regents’ counsel stated that “recirculation adds four to six months to the [CEQA review] process”; counsel for the Laurel Heights Improvement Association estimated that recirculation of the final EIR would add “two to three months.” With these comments in mind, I observe that the Regents' decision not to recirculate the final EIR, despite that document’s inclusion of “significant new information” within the meaning of section 21092.1, has led to the addition of nearly four years to the CEQA review process. Thus, despite the Regents’ assertion that the Laurel Heights Improvement Association unreasonably has delayed the project, it appears to me that the Regents’ disregard of both the applicable statutory provisions and this court’s prior admonition to the Regents “to provide sufficient meaningful information” in the EIR (Laurel Heights I, supra, 47 Cal.3d at p. 399), constitutes a major cause of “this continuing controversy” understandably lamented by the majority. (Maj. opn., ante, at p. 1120.)