such changes do not obligate EPA to provide Federal funds for any costs incurred by the fellow in excess of the assistance amount unless the award official approves the change in advance under § 46.150(a). The fellow must inform the EPA project officer in writing before implementing minor changes. (The information collection requirements contained in paragraph (b) were approved by the Office of Management and Budget under control number 2010-0004) § 46.155 Supplemental conditions. Recipients of a State or local fellowship receiving financial assistance under section 1442(d)(2) of the Safe Drinking Water Act, as amended; sections 104(b)(5) and (g)(3)(B) of the Clean Water Act as amended; and section 8001 of the Solid Waste Disposal Act must agree to remain in the employment of the State or local agency that recommended the recipient for an EPA fellowship for twice the period of the fellowship. If the recipient fails to perform this obligation the recipient may be required to repay the amount of the EPA fellowship. § 46.160 Acceptance of fellowship award. The applicant accepts the fellowship by signing and returning the fellowship agreement to the EPA award official within three weeks after receipt, or within any extension of such time that may be permitted by the EPA award official. If the applicant does not sign and return the agreement to the award official or request an extension of the acceptance time within three calendar weeks after receiving the agreement, the offer is null and void. § 46.165 Duration of fellowship. (a) Full-time fellowships will not exceed one year. (b) Part-time fellowships will not exceed three years. § 46.170 Initiation of studies. (a) The fellow must submit EPA 5770-7 "Fellowship Activation Notice" when they start their course of studies. (b) If the EPA Grants Administration Division has not received the signed Fellowship Activation Notice within six months following the date of the award, EPA may terminate the fellowship. (The information collection requirements contained in paragraph (a) were approved by the Office of Management and Budget under control number 2010-0004) § 46.175 Completion of studies. Fellows must submit EPA Form 5770-9 "EPA Fellowship Termination Notice," when the fellow completes the course of study. (Approved by the Office of Management and Budget under control number 20100004) § 46.180 Payment. (a) EPA will pay stipends directly to the fellow on a monthly basis or any other basis approved by the Project Officer, only after EPA has received the signed EPA Form 5770-7, "Fellowship Activation Notice." (b) EPA will pay the book allowance directly to the fellow only after EPA receives the signed EPA Form 5770-7. (c) EPA will pay tuition and fees in a lump payment directly to the sponsoring institution only after EPA has received the signed EPA Form 5770-7. (The information collection requirements contained in paragraph (a) were approved by the Office of Management and Budget under control number 2010-0004) SUBCHAPTER C-AIR PROGRAMS PART 50-NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS Sec. 50.1 Definitions. 50.2 Scope. 50.11 National primary and secondary ambient air quality standard for nitrogen dioxide. 50.12 National primary and secondary ambient air quality standards for lead. APPENDIX A-REFERENCE METHOD FOR THE DETERMINATION OF SULFUR DIOXIDE IN (PARAROSANILINE ATMOSPHERE THE METHOD) APPENDIX B-REFERENCE METHOD FOR THE DETERMINATION OF SUSPENDED PARTICULATE MATTER IN THE ATMOSPHERE (HIGHVOLUME METHOD) APPENDIX C-MEASUREMENT PRINCIPLE AND APPENDIX D-MEASUREMENT PRINCIPLE AND APPENDIX G-REFERENCE METHOD FOR THE APPENDIX H-INTERPRETATION OF THE NATIONAL AMBIENT AIR QUALITY STANDARDS FOR OZONE APPENDIX I-[RESERVED] (a) As used in this part, all terms not defined herein shall have the meaning given them by the Act. (b) "Act" means the Clean Air Act, as amended (42 U.S.C. 1857-18571, as amended by Pub. L. 91–604). (c) "Agency" means the Environmental Protection Agency. (d) "Administrator" means the Administrator of the Environmental Protection Agency. (e) "Ambient air" means that portion of the atmosphere, external to buildings, to which the general public has access. a (f) "Reference method" means method of sampling and analyzing the ambient air for an air pollutant that is specified as a reference method in an appendix to this part, or a method that has been designated as a reference met) od in accordance with Part 53 of this chapter; it does not include a method for which a reference method designation has been cancelled in accordance with § 53.11 or § 53.16 of this chapter. (g) "Equivalent method" means a method of sampling and analyzing the ambient air for an air pollutant that has been designated as an equivalent method in accordance with Part 53 of this chapter; it does not include a method for which an equivalent method designation has been cancelled in accordance with § 53.11 or § 53.16 of this chapter. (h) "Traceable" means that a local standard has been compared and certified either directly or via not more than one intermediate standard, to a primary standard such as a National Bureau of Standards Standard Reference Material (NBS SRM), or a USEPA/NBS-approved Certified Reference Material (CRM). [36 FR 22384, Nov. 25, 1971, as amended at 41 FR 11253, Mar. 17, 1976; 48 FR 2529, Jan. 20, 1983] § 50.2 Scope. (a) National primary and secondary ambient air quality standards under section 109 of the Act are set forth in this part. (b) National primary ambient air quality standards define levels of air quality which the Administrator judges are necessary, with an adequate margin of safety, to protect the public health. National secondary ambient air quality standards define levels of air quality which the Administrator judges necessary to protect the public welfare from any known or anticipated adverse effects of a pollutant. Such standards are subject to revision, and additional primary and secondary standards may be promulgated as the Administrator deems necessary to protect the public health and welfare. (c) The promulgation of national primary and secondary ambient air quality standards shall not be considered in any manner to allow significant deterioration of existing air quality in any portion of any State. (d) The proposal, promulgation, or revision of national primary and secondary ambient air quality standards shall not prohibit any State from establishing ambient air quality standards for that State or any portion thereof which are more stringent than the national standards. § 50.3 Reference conditions. All measurements of air quality are corrected to a reference temperature of 25° C. and to a reference pressure of 760 millimeters of mercury (1,013.2 millibars). § 50.4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). The national primary ambient air quality standards for sulfur oxides measured as sulfur dioxide by the reference method described in Appendix A to this part, or by an equivalent method, are: (a) 80 micrograms per cubic meter (0.03 p.p.m.)-annual arithmetic mean. (b) 365 micrograms per cubic meter (0.14 p.p.m.)-Maximum 24-hour concentration not to be exceeded more than once per year. § 50.5 National secondary ambient air quality standards for sulfur oxides (sulfur dioxide). The national secondary ambient air quality standard for sulfur oxide measured as sulfur dioxide by the reference method described in Appendix A to this part, or by any equivalent method is 1,300 micrograms per cubic meter (0.5 p.p.m.) maximum 3-hour concentration not to be exceeded more than once per year. [38 FR 25681, Sept. 14, 1973] § 50.6 National primary and secondary ambient air quality standards for particulate matter. (a) The level of the national primary and secondary 24-hour ambient air quality standards for particulate matter is 150 micrograms per cubic meter (μg/m3), 24-hour average concentration. The standards are attained when the expected number of days per calendar year with a 24-hour average concentration above 150 μg/m3, as determined in accordance with Appendix K to this part, is equal to or less than one. (b) The level of the national primary and secondary annual standards for particulate matter is 50 micrograms per cubic meter (μg/m3), annual arithmetic mean. The standards are attained when the expected annual arithmetic mean concentration, as determined in accordance with Appendix K to this part, is less than or equal to 50 μg/m3. (c) For the purpose of determining attainment of the primary and secondary standards, particulate matter shall be measured in the ambient air as PM10 (particles with an aerodynamic diameter less than or equal to a nominal 10 micrometers) by: (1) A reference method based on Appendix J and designated in accordance with Part 53 of this chapter, or (2) An equivalent method designated in accordance with Part 53 of this chapter. [52 FR 24663, July 1, 1987] § 50.7 [Reserved] § 50.8 National primary ambient air quality standards for carbon monoxide. (a) The national primary ambient air quality standards for carbon monoxide are: (1) 9 parts per million (10 milligrams per cubic meter) for an 8-hour average concentration not to be exceeded more than once per year and (2) 35 parts per million (40 milligrams per cubic meter) for a 1-hour average concentration not to be exceeded more than once per year. (b) The levels of carbon monoxide in the ambient air shall be measured by: (1) A reference method based on Appendix C and designated in accordance with Part 53 of this chapter, or (2) An equivalent method designated in accordance with Part 53 of this chapter. (c) An 8-hour average shall be considered valid if at least 75 percent of the hourly average for the 8-hour period are available. In the event that only six (or seven) hourly averages are available, the 8-hour average shall be computed on the basis of the hours available using six (or seven) as the divisor. (d) When summarizing data for comparision with the standards, averages shall be stated to one decimal place. Comparison of the data with the levels of the standards in parts per million shall be made in terms of integers with fractional parts of 0.5 or greater rounding up. [50 FR 37501, Sept. 13, 1985] § 50.9 National primary and secondary ambient air quality standards for ozone. (a) The level of the national primary and secondary ambient air quality standards for ozone measured by a reference method based on Appendix D to this part and designated in accordance with Part 53 of this chapter, is 0.12 part per million (235 μg/m3). The standard is attained when the expect ed number of days per calendar year with maximum hourly average concentrations above 0.12 part per million (235 μg/m3) is equal to or less than 1, as determined by Appendix H. (Secs. 109 and 301 of the Clean Air Act, as amended (42 U.S.C. 7409, 7601)) [44 FR 8220, Feb. 8, 1979] § 50.10 [Reserved] § 50.11 National primary and secondary ambient air quality standards for nitrogen dioxide. (a) The level of the national primary ambient air quality standard for nitrogen dioxide is 0.053 parts per million (100 micrograms per cubic meter), annual arithmetic mean concentration. (b) The level of national secondary ambient air quality standard for nitrogen dioxide is 0.053 parts per million (100 micrograms per cubic meter), annual arithmetic mean concentration. (c) The levels of the standards shall be measured by: (1) A reference method based on Appendix F and designated in accordance with Part 53 of this Chapter, or (2) An equivalent method designated in accordance with Part 53 of this Chapter. (d) The standards are attained when the annual arithmetic mean concentration in a calendar year is less than or equal to 0.053 ppm, rounded to three decimal places (fractional parts equal to or greater than 0.0005 ppm must be rounded up). To demonstrate attainment, an annual mean must be based upon hourly data that are at least 75 percent complete or upon data derived from manual methods that are at least 75 percent complete for the scheduled sampling days in each calendar quarter. [50 FR 25544, June 19, 1985] § 50.12 National primary and secondary ambient air quality standards for lead. National primary and secondary ambient air quality standards for lead and its compounds, measured as elemental lead by a reference method based on Appendix G to this part, or by an equivalent method, are: 1.5 mi crograms per cubic meter, maximum arithmetic mean averaged over a calendar quarter. (Secs. 109, 301(a) Clean Air Act as amended (42 U.S.C. 7409, 7601(a))) [43 FR 46258, Oct. 5, 1978] APPENDIX A-REFERENCE METHOD FOR THE DETERMINATION OF SULFUR DIOXIDE IN THE ATMOSPHERE (PARAROSANILINE METHOD) 1.0 Applicability. 1.1 This method provides a measurement of the concentration of sulfur dioxide (SO2) in ambient air for determining compliance with the primary and secondary national ambient air quality standards for sulfur oxides (sulfur dioxide) as specified in § 50.4 and § 50.5 of this chapter. The method is applicable to the measurement of ambient SO2 concentrations using sampling periods ranging from 30 minutes to 24 hours. Additional quality assurance procedures and guidance are provided in Part 58, Appendixes A and B, of this chapter and in references 1 and 2. 2.0 Principle. 2.1 A measured volume of air is bubbled through a solution of 0.04 M potassium tetrachloromercurate (TCM). The SO2 present in the air stream reacts with the TCM solution to form a stable monochlorosulfonatomercurate(3) complex. Once formed, this complex resists air oxidation(4, 5) and is stable in the presence of strong oxidants such as ozone and oxides of nitrogen. During subsequent analysis, the complex is reacted with acid-bleached pararosaniline dye and formaldehyde to form an intensely colored pararosaniline methyl sulfonic acid.(6) The optical density of this species is determined spectrophotometrically at 548 nm and is directly related to the amount of SO2 collected. The total volume of air sampled, corrected to EPA reference conditions (25° C, 760 mm Hg (101 kPa]), is determined from the measured flow rate and the sampling time. The concentration of SO2 in the ambient air is computed and expressed in micrograms per standard cubic meter (μg/ std m3). Range. 3.0 3.1 The lower limit of detection of SO, in 10 mL of TCM is 0.75 μg (based on collaborative test results).(7) This represents a concentration of 25 μg SO2/m3 (0.01 ppm) in an air sample of 30 standard liters (short-term sampling) and a concentration of 13 μg SO1/ m3 (0.005 ppm) in an air sample of 288 standard liters (long-term sampling). Concentrations less than 25 μg SO2/m3 can be measured by sampling larger volumes of ambient air; however, the collection efficiency falls off rapidly at low concentrations.(8, 9) Beer's law is adhered to up to 34 μg of SO, in 25 mL of final solution. This upper limit of the analysis range represents a concentration of 1,130 μg SO2/m3 (0.43 ppm) in an air sample of 30 standard liters and a concentration of 590 μg SO2/m3 (0.23 ppm) in an air sample of 288 standard liters. Higher concentrations can be measured by collecting a smaller volume of air, by increasing the volume of absorbing solution, or by diluting a suitable portion of the collected sample with absorbing solution prior to analysis. 4.0 Interferences. 4.1 The effects of the principal potential interferences have been minimized or eliminated in the following manner: Nitrogen oxides by the addition of sulfamic acid,(10, 11) heavy metals by the addition of ethylenediamine tetracetic acid disodium salt (EDTA) and phosphoric acid,(10, 12) and ozone by time delay.(10) Up to 60 μg Fe (III), 22 μg V (V), 10 μg Cu (II), 10 μg Mn (II), and 10 μg Cr (III) in 10 mL absorbing reagent can be tolerated in the procedure.(10) No significant interference has been encountered with 2.3 μg NH,.(13) 5.0 Precision and Accuracy. 5.1 The precision of the analysis is 4.6 percent (at the 95 percent confidence level) based on the analysis of standard sulfite samples.(10) 5.2 Collaborative test results (14) based on the analysis of synthetic test atmospheres (SO, in scrubbed air) using the 24-hour sampling procedure and the sulfite-TCM calibration procedure show that: • The replication error varies linearly with concentration from ±2.5 μg/m3 at concentrations of 100 μg/m3 to ±7 μg/m3 at concentrations of 400 μg/m3. • The day-to-day variability within an individual laboratory (repeatability) varies linearly with concentration from ±18.1 μg/ m3 at levels of 100 μg/m3 to ±50.9 μg/m3 at levels of 400 μg/m3. • The day-to-day variability between two or more laboratories (reproducibility) varies linearly with concentration from ±36.9 μg/m3 at levels of 100 μg/m3 to ±103.5 μg/m3 at levels of 400 μg/m3. • The method has a concentration-dependent bias, which becomes significant at the 95 percent confidence level at the high concentration level. Observed values tend to be lower than the expected SO2 concentration level. 6.0 Stability. 6.1 By sampling in a controlled temperature environment of 15° ±10° C, greater than 98.9 percent of the SO2-TCM complex is retained at the completion of sampling. (15) If kept at 5° C following the completion of sampling, the collected sample has been |