Knocking your NOx off

I just started learning about nitrous oxide (NOx). When we electrified our house, we did it to burn less carbon. I signed up for MCE Deep Green so our share of energy usage would come from renewable sources. I felt good about paying extra (the notorious “green premium”) for our all-electric home appliances.

I feel even better now. Nitrous oxide pollution has long been recognized as a significant contributor to air pollution and climate change, posing a threat to both human health and the environment. To address this pressing issue, the Board of Directors of the Air District held a public hearing on March 15, 2023, to consider the adoption of proposed amendments to Regulation 9, which addresses inorganic gaseous pollutants. These proposed amendments include the introduction of zero NOx standards for space and water heating appliances and an ultra-low NOx standard for furnaces, which would have a profound impact on reducing NOx emissions.

The amendments were adopted!

The Need for Stronger NOx Standards

NOx emissions are produced by various sources, including transportation, industrial processes, and building appliances, such as natural gas-fired boilers, water heaters, and fan-type residential central furnaces. NOx pollution contributes to the formation of ground-level ozone, smog, and fine particulate matter, which are associated with respiratory and cardiovascular health issues, particularly in vulnerable populations such as children, the elderly, and people with pre-existing health conditions. Additionally, NOx emissions have been linked to adverse environmental impacts, including acid rain, eutrophication of water bodies, and the depletion of stratospheric ozone.

The amendments to Rules 9-4 and 9-6 are a vital step in mitigating these harmful effects. By implementing a zero NOx standard for both space and water heating appliances and an ultra-low NOx standard for furnaces, the amendments will significantly reduce NOx emissions from residential and commercial buildings. These new standards are set to be enforced from 2027 to 2031, depending on the appliance, providing a clear timeline for manufacturers and consumers to transition to cleaner and more efficient technologies.

Addressing Concerns

While the Draft Environmental Impact Report (EIR) for the proposed amendments concluded that there would be potentially significant and unavoidable impacts associated with utilities, services systems, and noise, it is important to put these concerns into perspective. The increased energy demand resulting from the replacement of existing natural gas-fired appliances with electric ones can be mitigated by continued investments in renewable energy sources and improvements in grid infrastructure. Moreover, the benefits of reducing NOx emissions, such as improved air quality and reduced greenhouse gas emissions, far outweigh the potential challenges associated with increased energy demand. Furthermore, I believe the market will solve grid demand issues and supply will ramp up over time to bring prices down.

Similarly, the noise impacts associated with certain zero NOx equipment can be addressed through technological advancements and proper installation techniques. In many cases, the noise levels of these appliances can be reduced to acceptable levels, ensuring that they do not pose a significant nuisance to residents. My heat pump water heater is louder than my old gas one, but we put it in the garage and don’t hear it. Plus, the cold air it blows as exhaust is amazing in the summer.


I’m glad the BAAQMD passed the amendments to Regulation 9. By adopting these stricter NOx standards, we can significantly reduce air pollution, protect public health, and mitigate the impacts of climate change.

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