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Tritium DAC and Unit Converter (Bq/m³ ↔ µCi/mL ↔ DAC)

Convert a tritium-in-air concentration between Bq/m³, µCi/m³, µCi/mL and pCi/L. See it as a fraction of the HTO and HT derived air concentrations, as DAC-hours and estimated mrem for a shift, and as a multiple of the air effluent concentration.

Iodine Air Systems technical team Published September 29, 2026 Cites 10 CFR 20 / 835

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Quick answer

The occupational DAC for tritiated water (HTO) is 2 × 10⁻⁵ µCi/mL = 7.4 × 10⁵ Bq/m³ (10 CFR 20 Appendix B; 10 CFR 835 Appendix A). The DOE DAC for elemental tritium is 2 × 10⁻¹ µCi/mL, 10,000 times higher. 1 µCi/mL = 3.7 × 10¹⁰ Bq/m³; 1 µCi/m³ = 3.7 × 10⁴ Bq/m³; 1 DAC-hour ≈ 2.5 mrem. The annual-average air effluent concentration for H-3 is 1 × 10⁻⁷ µCi/mL (3,700 Bq/m³).

Concentration value Unit Exposure time (hours)

DAC values: HTO 2 × 10⁻⁵ µCi/mL (10 CFR 20 Appendix B; 10 CFR 835 Appendix A); elemental tritium 2 × 10⁻¹ µCi/mL (10 CFR 835 Appendix A). The mrem estimate uses 2.5 mrem per DAC-hour and ignores respiratory protection. It is a planning aid, not a dose record.

Tritium conversion reference table

Quantity	Bq/m³	Equivalent
1 µCi/m³	3.7 × 10⁴ Bq/m³	0.05 DAC (HTO)
1 µCi/mL	3.7 × 10¹⁰ Bq/m³	50,000 DAC (HTO)
HTO DAC: 2 × 10⁻⁵ µCi/mL	7.4 × 10⁵ Bq/m³	1 DAC (10 CFR 20 App. B; 10 CFR 835 App. A)
Elemental tritium DAC (DOE): 2 × 10⁻¹ µCi/mL	≈ 7.4 × 10⁹ Bq/m³ (DOE table lists 9 × 10⁹)	10,000 × HTO DAC (10 CFR 835 App. A)
Air effluent concentration H-3 (annual average): 1 × 10⁻⁷ µCi/mL	3,700 Bq/m³	0.005 DAC (10 CFR 20 App. B Table 2)
1 DAC-hour	—	≈ 2.5 mrem (2,000 DAC-h = 5 rem)
1 pCi/L	37 Bq/m³	—
1 Ci	3.7 × 10¹⁰ Bq	—

How the conversions work

1 Ci = 3.7 × 10¹⁰ Bq, and 1 m³ = 10⁶ mL, so 1 µCi/mL = 3.7 × 10¹⁰ Bq/m³ and 1 µCi/m³ = 3.7 × 10⁴ Bq/m³. The occupational DAC for tritiated water, 2 × 10⁻⁵ µCi/mL, is therefore 7.4 × 10⁵ Bq/m³ (740 kBq/m³). A worker breathing air at 1 DAC for 2,000 hours would reach the 5 rem annual limit, so one DAC-hour ≈ 2.5 mrem.

What this means for choosing a monitor

IAS-T air monitors start at 3.7 × 10⁴ Bq/m³ = 1 µCi/m³ = 0.05 DAC, so they read a factor of 20 below a 1 DAC alarm. Room and process monitors reach 3.7 × 10¹¹ Bq/m³ (500,000 DAC). For concentrations near the effluent concentration value (3,700 Bq/m³), use integrating bubbler or desiccant samplers with liquid scintillation counting; they are more sensitive than real-time ion chambers. See how to choose a tritium monitor or all IAS-T models.

Link to this converter

Free to use and link from procedures, training pages and course notes. Copy this HTML:

<a href="https://iodineairsystems.com/tritium-monitors/tritium-dac-unit-converter/">Tritium DAC &amp; unit converter (Bq/m³ ↔ µCi/mL ↔ DAC)</a>

FAQ

What is the DAC for tritium in Bq/m³?

For tritiated water (HTO) the DAC is 2 × 10⁻⁵ µCi/mL, which equals 7.4 × 10⁵ Bq/m³ (740 kBq/m³), per 10 CFR 20 Appendix B and 10 CFR 835 Appendix A.

How do I convert Bq/m³ to µCi/mL?

Divide by 3.7 × 10¹⁰. For example, 7.4 × 10⁵ Bq/m³ ÷ 3.7 × 10¹⁰ = 2 × 10⁻⁵ µCi/mL.

How many mrem is one DAC-hour?

About 2.5 mrem. Breathing air at 1 DAC for 2,000 hours corresponds to the 5 rem annual occupational limit, so 5,000 mrem ÷ 2,000 h = 2.5 mrem per DAC-hour.

What is the tritium air effluent concentration limit?

10 CFR 20 Appendix B Table 2 lists an annual-average effluent concentration of 1 × 10⁻⁷ µCi/mL for H-3 in air, which equals 3,700 Bq/m³, or 0.005 of the HTO DAC.

Is elemental tritium (HT) less hazardous than HTO?

Yes, by DAC. 10 CFR 835 Appendix A lists 2 × 10⁻¹ µCi/mL for elemental tritium and 2 × 10⁻⁵ µCi/mL for tritiated water, a factor of 10,000. HT can convert to HTO in the environment and in the body, which is one reason facilities monitor both forms.

Need a tritium monitor?

Portable, area, glovebox, HT/HTO, wipe and OEM models. US 120 V versions. Price on quotation.

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