---
kind: "section"
citation: "40 C.F.R. § 60.6495"
title: "40"
number: "60.6495"
heading: "How do I convert my 1-hour arithmetic averages into appropriate averaging times and units?"
url: "https://uscodex.org/cfr/40/60.6495"
---

# §60.6495. How do I convert my 1-hour arithmetic averages into appropriate averaging times and units?

- (a) Use equation 1 in [§ 60.6680(a)](/cfr/40/60.6680.md?p=a) to calculate emissions at 7 percent oxygen.
- (b) Use the test methods in Table 4 to [Subpart WWWW](/cfr/40/subpartWWWW.md) to calculate the 24-hr daily geometric average concentrations and percent reductions of sulfur dioxide emissions and the 24-hr daily arithmetic average for concentrations of nitrogen oxides.
- (c) Calculate the 4-hour block or 24-hour daily arithmetic averages specified in Table 2 to [Subpart WWWW](/cfr/40/subpartWWWW.md) (as applicable) from 1-hour arithmetic averages expressed in parts per million by volume corrected to 7 percent oxygen (dry basis) for concentrations of carbon monoxide. CEMS data during warmup, startup, and shutdown, as defined in this subpart, are not corrected to 7 percent oxygen, and are used as measured.
- (d) If you elect to continuously monitor emissions of particulate matter, mercury, cadmium, lead, or hydrogen chloride, use EPA Reference Method 19, [section 12.4.1](/cfr/40/12.4.1.md), in appendix A of this part, to calculate a 24-hour daily block arithmetic average for emission concentrations.

## Notes

### Source

Source: 91 FR 11860, Mar. 10, 2026, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 7401 et seq.

### Source

Source: 36 FR 24877, Dec. 23, 1971, unless otherwise noted.