Governor Walz’s California Car Mandates Will Have No Meaningful Impact on Pollution

In September, the Walz Administration announced its intention to force Minnesotans to comply with low-emissions vehicle (LEV) and ‘zero’-emissions vehicle (ZEV) regulations developed by unelected bureaucrats on the California Air Resources Board (CARB). Instead of asking the legislature to approve this move, Governor Walz wants to impose these regulations by using the rule-making process of the Minnesota Pollution Control Agency (MPCA).

Yesterday, I wrote about the implications these regulations would have on low-income and minority communities. While proponents of this rule argue it will reduce air pollution, Minnesota’s air is already clean, and imposing these regulations will simply add extra cost while still failing to address the fact that indoor air quality is often worse than outdoor air quality.

No Impact on Traditional Pollutants

Any benefits of reducing traditional pollutants through the ZEV and LEV rulemaking are likely overstated because emissions of criteria pollutants from American cars have fallen dramatically in the last four decades.

According to the U.S. Environmental Protection Agency, new passenger vehicles are 98-99 percent cleaner for most tailpipe pollutants compared to the 1960s.[1] Technologies have created more efficient engines and catalytic converters, which have greatly reduced tailpipe emissions from cars. Furthermore, fuels are much cleaner—lead has been eliminated, and sulfur levels are more than 90 percent lower than they were prior to regulation.

These technologies have contributed to Minnesota having some of the cleanest air in the world. In fact, according to the Minnesota Pollution Control Agency graph below, our air already meets the most stringent state and federal standards for air quality, which are designed to protect even vulnerable populations like children and the elderly.[2] Pollution from sulfur dioxide and nitrogen dioxide are especially low compared to established benchmarks.

Annual air quality reports from MPCA corroborate this data. The 2019 edition of “The Air We Breathe” concluded that Minnesota’s air quality meets all federal standards and pollution levels are decreasing statewide.[3]

Particularly noteworthy was MPCA’s finding that there were zero “bad air” days and in 2018, seven of the nine “bad air” days were caused by smoke from distant wildfires that was transported into Minnesota.

Among emissions sources in Minnesota, MPCA data show neighborhood sources, such as dry cleaners, home heating, backyard fires, etc, are the largest contributors of criteria air pollutants in the state, whereas emissions from vehicles are much lower in comparison. Of these emissions, on-road vehicles constitute 24 percent of the total, which is 31 percent less than those emitted by neighborhood sources.

Center of the American Experiment believes Minnesota has made tremendous progress on improving its outdoor air quality, and this progress should be widely celebrated. However, in order to maintain this progress, people it appears MPCA’s myopic focus on outdoor air quality may be detracting from its study of indoor air quality and its impact on the health and wellbeing of Minnesotans.

Indoor Air Quality is Worse than Outdoor Air Quality

The U.S. Environmental Protection Agency states that in the last several years, a growing body of scientific evidence has indicated that the air within homes and other buildings can be more seriously polluted than the outdoor air in even the largest and most industrialized cities.[4] According to EPA, levels of indoor air pollutants are often two to five times higher than outdoor levels, and in some cases these levels can exceed 100 times that of outdoor levels of the same pollutants.[5]

Other research indicates that people spend approximately 90 percent of their time indoors. Thus, for many people, the risks to health may be greater due to exposure to air pollution indoors than outdoors.[6]

In addition, people who may be exposed to indoor air pollutants for the longest periods of time are often those most susceptible to the effects of indoor air pollution. Such groups include the young, the elderly and the chronically ill, especially those suffering from respiratory or cardiovascular disease.[7] Conversely, these groups are also the least likely to be affected by outdoor air quality conditions due to spending the majority of their time indoors.

Interestingly, EPA states “If too little outdoor air enters a home, pollutants can accumulate to levels that can pose health and comfort problems. Unless they are built with special mechanical means of ventilation, homes that are designed and constructed to minimize the amount of outdoor air that can “leak” into and out of the home may have higher pollutant levels than other homes.”

Imposing additional LEV and ZEV regulations on the automotive industry will increase costs for consumers but will do little to address the most pressing air quality challenges facing demographics MPCA considers to be among the most vulnerable the state.

Therefore, we do not believe the cost of these rules can be scientifically justified on a cost-benefit analysis on the basis of reductions in criteria air pollutants.

[1] U.S. Environmental Protection Agency, “History of Reducing Pollution from Transportation in the United States,” Accessed November 26, 2019,

[2] Minnesota Pollution Control Agency, “Criteria Pollutant Data Explorer,” Explore Interactive Air Monitoring Data, Accessed November 26, 2019,

[3] Todd Biwen, “The Air We Breathe: The State of Minnesota’s Air Quality 2019,” Minnesota Pollution Control Agency, Accessed November 26, 2019,

[4] U.S. Environmental Protection Agency, “The Inside Story: A Guide to Indoor Air Quality,” Accessed November 27, 2019,

[5] Medical Associates of Northwest Arkansas, “Indoor Air vs. Outdoor Air,” Accessed November 27, 2019,

[6] U.S. Environmental Protection Agency, “The Inside Story: A Guide to Indoor Air Quality,” Accessed November 27, 2019,

[7] U.S. Environmental Protection Agency, “The Inside Story: A Guide to Indoor Air Quality,” Accessed November 27, 2019,