Ozone Depleting Substances

This report was last updated in February 2022. The most up-to-date version of this report was published in November 2022 and covers refrigerant destruction in general, of which ODS destruction is a subset.


Certain gases used as refrigerants and foams are classified as “Ozone Depleting Substances”, or ODS. When they enter the atmosphere, these gases can warm the earth at a rate orders of magnitude above carbon dioxide (CO2). Although the production of many of these gases is banned under the Montreal Protocol, large quantities of ODS still exist in appliances or stockpiles. If these gases are not properly disposed of, most will eventually leak or be released into the atmosphere. Organizations can find and destroy these gases, generating emissions credits in the process.

We find these offsets to be among the most credible on the market. We currently recommend one ODS-destroying organization, Tradewater, which sells offsets directly from its website.


Although CO2 is the most well-known greenhouse gas (GHG), other substances released into the atmosphere by human activity also have warming potential. Some of the most powerful warming gases come from refrigerants and foams and can have up to 10,000 times the warming effect of CO2. These include chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs), which are sometimes found in aerosols, refrigerators, and air conditioners. As many of these substances deplete the ozone layer, they are frequently described as “Ozone Depleting Substances” (ODS).

Production of these chemicals is banned under the universally ratified Montreal Protocol, including the Kigali Amendment in 2016. But large quantities still exist, and the use of pre-existing ODS is not banned in most countries. If not destroyed, ODS will continue to leak from appliances and storage containers, entering the atmosphere and adding to warming. Project Drawdown identifies refrigerant management as one of the most promising interventions to reduce warming.

In theory, ODS destruction is a good fit for carbon offsetting. ODS destruction has no commercial value, so it is unlikely to occur in the absence of further government regulation, philanthropic donations, or carbon offsets. At this time, plenty of existing ODS still needs to be found and destroyed. Because ODS destruction projects can be ramped up semi-linearly with funding—i.e. they do not require large upfront capital investments but instead utilize a certain amount of funds per unit of ODS destroyed—revenue from selling offsets from a previous project can easily be reinvested in future ODS destruction.


ODS destruction projects are considered emissions avoidance, as they prevent emissions that would have occurred had the ODS leaked into the atmosphere.


There are a few elements to establishing causality of ODS destruction projects:

  • Conversion of ODS into less harmful substances

  • Establishing the counterfactual of ODS release into the atmosphere

  • Ensuring that destruction of ODS does not lead to more production of harmful gases

  • Accounting for the carbon footprint of the removal activities

We tackle each in more detail below.

Conversion of ODS into less harmful substances

ODS destruction projects reduce GHGs by incinerating the ODS. While measuring the exact amount of gases destroyed is straightforward, converting this into the amount of CO2-equivalent gas removed requires understanding the “global warming potential” (GWP) of both the ODS and the byproducts of ODS incineration. These have been established by the IPCC, who are consistently updating their lists of conversion factors. Depending on the gas being destroyed, incinerating ODS can lead to thousands of times less warming over a hundred years than simply letting the gases escape.

Establishing the counterfactual of ODS release into the atmosphere

If not destroyed, would ODS have been sequestered indefinitely in canisters and appliances, or would it leak into the atmosphere and cause warming? Even under the best conditions, many ODS storage containers will slowly leak, and improper end-of-life disposal of appliances can result in complete release. Offset certifiers have standard assumptions for leakage over time. For instance, the Verra protocol allows projects to claim 100% of destruction to be additional when ODS are recovered from appliances at their end-of-life; for canisters that could be reused or stored, projects may estimate expected cumulative leakage over ten years and claim that share of destruction as additional. We believe these are reasonably conservative assumptions and accept them for offset projects that we analyze.

Ensuring that the destruction of ODS does not lead to more production of harmful gases

Finally, we may worry that destroying these gases might cause similar chemicals to be produced to meet the demand for this type of gas, a phenomenon termed “leakage.” Since production of these gases is banned in all countries under the Montreal Protocol, they cannot be reproduced, but they might be replaced with non-banned gases that also have warming effects when released into the atmosphere. This is not a problem with refrigerants captured from end-of-life appliances, but it could be an issue for stockpiled gases.

Accounting for the carbon footprint of the removal activities

Finding and incinerating ODS can require travel and shipping, which in itself can lead to CO2 emissions. However, these life cycle emissions are generally taken into account by the offset certifier when calculating the total emissions reduced.

Project-Level and Marginal Additionality

There is no other market for ODS destruction. Additionality is much more straightforward to establish for ODS projects than for other carbon offset sectors. Most countries do not have any regulations on the use and destruction of existing ODS, even if their production is banned under the Montreal Protocol. Since no market exists for the destruction of these gases apart from the carbon offset market, ODS destruction projects have to rely on offsets to survive.


When ODS are destroyed, their contributions to warming are permanently removed. Reversal is not a concern.


ODS projects do not generally offer any co-benefits, but preventing ODS from escaping into the atmosphere can prevent damage to the ozone layer.


Giving Green has only found one organization selling ODS destruction offsets to the public, Tradewater. We investigate their cost effectiveness in our recommendation.

Assessment of ODS projects

We find ODS destruction carbon offsets to be one of the more compelling types of carbon offsets available. We have only found one ODS offset that we recommend, which is provided by Tradewater.