Historical prices, with district records through 2026
These are recorded transactions, not current offers. The tables below cover different reporting periods. For newer district-specific records, use the district history links or annual market reports. Current availability, minimum purchases and fees require a seller quote.
Recorded prices span an enormous range by district and pollutant. In 2023 Imperial County NOx cleared $2,000–$3,100 per ton while South Coast NOx cleared $380,000–$420,000, and South Coast's own 2024 report puts its priced NOx trades at $416,000–$486,000. Because eligibility and supply differ by district, local scarcity affects the price: the same pollutant can trade for a few thousand dollars a ton in one district and hundreds of thousands in another.
South Coast AQMD recorded transactions, calendar year 2025
Source: South Coast AQMD Annual Publication of ERC Transactions, CY2025 (Health & Safety Code §40709.5; retrieved October 23, 2026). 25 certificate transfers, 13 with a purchase price; prices are $/ton/year as the district annualizes them. The three priced NOx transfers were 12 lb/day in all (2.19 tons a year). No CO or SOx transfer carried a price.
| Pollutant | Transfers | With price | Average $/ton | Low | High |
|---|
| NOx | 3 | 3 | $473,000 | $470,000 | $489,000 |
| PM10 | 2 | 1 | $450,000 | $450,000 | $450,000 |
| SOx | 2 | 0 | no priced transfer |
| ROG (HC/VOC) | 15 | 9 | $20,000 | $11,000 | $27,000 |
| CO | 3 | 0 | no priced transfer |
South Coast AQMD recorded transactions, calendar year 2024
Source: South Coast AQMD Annual Publication of ERC Transactions, CY2024 (Health & Safety Code §40709.5). 54 certificate transfers, 27 with a purchase price; prices are $/ton/year as the district annualizes them. The $5 CO transfer and the single $3,000 ROG trade are nominal; the other 18 priced ROG trades cleared $19,000–$25,000.
| Pollutant | Transfers | With price | Average $/ton | Low | High |
|---|
| NOx | 4 | 3 | $418,000 | $416,000 | $486,000 |
| PM10 | 10 | 3 | $423,000 | $333,000 | $472,000 |
| SOx | 10 | 1 | $327,000 | $327,000 | $327,000 |
| ROG (HC/VOC) | 29 | 19 | $23,000 | $3,000 | $25,000 |
| CO | 1 | 1 | $5 | $5 | $5 |
Recorded 2023 ERC transaction prices, by district (CARB)
Source: CARB Emission Reduction Offset Transaction Costs Summary Report for 2023. 160 monetary transactions across ten districts; 25 districts reported none. CARB treats HC as equivalent to ROG/VOC.
Imperial County APCD, 93 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $2,500 | $2,625.63 | $2,000 | $3,098.35 |
| HC (ROG/VOC) | $1,100 | $1,841.69 | $1,000 | $2,691.51 |
| PM10 | $485 | $478.33 | $400 | $600 |
Yolo-Solano AQMD, 21 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $25,000 | $24,830.27 | $23,750 | $40,000 |
| NOx | $37,800 | $37,800 | $37,800 | $37,800 |
| PM10 | $17,500 | $17,500 | $17,500 | $17,500 |
| SOx | $17,000 | $17,000 | $17,000 | $17,000 |
| CO | $3,400 | $3,400 | $3,400 | $3,400 |
Feather River AQMD, 11 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $30,000 | $27,197.84 | $25,000 | $30,000 |
| NOx | $30,000 | $30,000 | $30,000 | $30,000 |
| PM10 | $32,593.58 | $32,593.59 | $32,593.57 | $32,593.59 |
South Coast AQMD, 9 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $400,000 | $383,862.55 | $380,000 | $420,000 |
| PM10 | $460,000 | $458,333.33 | $460,000 | $460,000 |
| HC (ROG/VOC) | $22,000 | $17,559.5 | $12,000 | $27,000 |
Bay Area AQMD, 7 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $29,000 | $24,019.02 | $23,235.72 | $29,090 |
Mojave Desert AQMD, 7 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $35,000 | $35,000 | $35,000 | $35,000 |
| PM10 | $9,000 | $4,362.32 | $1,000 | $9,000 |
San Joaquin Valley APCD, 4 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $174,845 | $174,875.28 | $174,690 | $175,000 |
| NOx | $13,750 | $12,538.89 | $9,500 | $18,000 |
Placer County APCD, 4 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $25,000 | $25,297.89 | $25,000 | $30,000 |
Santa Barbara County APCD, 2 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $125,000 | $125,000 | $125,000 | $125,000 |
Ventura County APCD, 2 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $67,275 | $67,275 | $67,275 | $67,275 |
| NOx | $65,000 | $65,000 | $65,000 | $65,000 |
Recorded 2022 ERC transaction prices, by district (CARB)
Source: CARB Emission Reduction Offset Transaction Cost Summary Report for 2022, reported under Health & Safety Code §40709.5. Six districts recorded trades; 29 reported none. CARB treats HC as equivalent to ROG/VOC.
Imperial County APCD, 84 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $2,700 | $2,734.86 | $500 | $3,188.95 |
| HC (ROG/VOC) | $1,100 | $1,445.92 | $1,000 | $1,850 |
| PM10 | $425 | $449.49 | $375 | $539.67 |
San Joaquin Valley APCD, 53 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $69,950 | $67,189.24 | $2,730 | $174,690 |
| NOx | $19,000 | $21,938.36 | $57 | $50,000 |
| PM10 | $10,150 | $9,817.83 | $5,000 | $29,762 |
| SOx | $57 | $6,223.61 | $57 | $7,250 |
South Coast AQMD, 24 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $356,332.7 | $356,332.7 | $356,332.7 | $356,332.7 |
| PM10 | $318.78 | $142,805.11 | $318.78 | $427,777.78 |
| HC (ROG/VOC) | $21,875 | $7,499.64 | $314.02 | $27,397.26 |
| SOx | $1,190.55 | $1,190.47 | $1,189.92 | $1,191.18 |
Bay Area AQMD, 21 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $22,000 | $21,924.09 | $7,974 | $31,000 |
| PM10 | $20,000 | $20,000 | $20,000 | $20,000 |
| HC (ROG/VOC) | $9,125 | $8,925.03 | $8,500 | $10,000 |
| SOx | $10,025.5 | $71.14 | $51 | $20,000 |
Yolo-Solano AQMD, 2 transactions
| Pollutant | Median $/ton | Average | Low | High |
|---|
| NOx | $75,000 | $75,000 | $75,000 | $75,000 |
| PM10 | $16,750 | $16,750 | $16,750 | $16,750 |
Placer County APCD, 1 transaction
| Pollutant | Median $/ton | Average | Low | High |
|---|
| HC (ROG/VOC) | $35,000 | $35,000 | $35,000 | $35,000 |
Yolo-Solano AQMD transaction history, 1998–2024
A long-running price series from the district's own transaction log:
| Pollutant | Low $/ton | High $/ton | Transactions | Years |
|---|
| NOx | $990 | $75,000 | 36 | 1998–2022 |
| VOC / ROG | $944 | $55,000 | 40 | 1999–2024 |
| PM10 | $1,000 | $40,000 | 50 | 1999–2024 |
| SOx | $500 | $17,000 | 30 | 2000–2021 |
| CO | $1 | $10,000 | 15 | 2002–2023 |
District transaction records
Beyond the statewide reports, four districts publish their own transaction records, sale by sale: San Joaquin Valley (annual cost reports, 2001 to date), Mojave Desert, Imperial County (2025) and Yolo-Solano (1998–2024). The Exchange reads every one; each district guide shows its full history year by year, and the whole set is downloadable.
Download every recorded transaction (CSV), district, date, pollutant, quantity and price exactly as the district records them, with the source document for each row.
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