Section 096-110-6 - Nitrogen Dioxide Ambient Air Quality StandardsA. The1-hour primary ambient air quality standard for nitrogen dioxide is a concentration of 100 ppb. The standard is met when the 98th percentile of 1-hour daily maximum concentrations, averaged over 3 years at a monitor, as determined in accordance with 40 CFR Part 50 Appendix S, does not exceed 100 ppb.B. The annual primary and secondary ambient air quality standard for nitrogen dioxide is a concentration of 53 ppb. The standard is met when the when the annual arithmetic mean concentration at a monitor, as determined in accordance with 40 CFR Part 50 Appendix S, does not exceed 53 ppb.06- 096 C.M.R. ch. 110, § 6