Will Trump ‘SAFE’ Rule for New Cars Harm Public Health?

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Will the Trump administration’s auto rule harm public health? That’s what all five majority witnesses and several Democratic members of the House Oversight Environment Subcommittee claimed at a recent hearing on the administration’s Safer Affordable Fuel-Efficient (SAFE) Vehicles rule.  

I was the sole minority witness at the hearing, titled “Trump’s Wrong Turn on Clean Cars.” My written testimony focused mainly on explaining (1) the legal necessity for terminating California’s de facto power to regulate fuel economy, and (2) the climatological irrelevance of the SAFE rule’s relaxation of motor vehicle carbon dioxide and mileage standards during model years 2020-2026.

At the hearing, majority witnesses and Democratic members denounced the SAFE rule as unlawful, anti-competitive, and damaging to public health. Yesterday, I submitted a supplemental testimony rebutting those allegations. Today’s post explains why the SAFE rule poses no danger to public health.

Will the SAFE Rule Increase Air Pollution?

The title of the hearing (“Trump’s Wrong Turn on Clean Cars”) implies the SAFE rule is an attack on “clean cars” and is “pro-polluter.” That is a false narrative.

The SAFE rule eliminates California’s power to regulate motor vehicle carbon dioxide emissions. Carbon dioxide is not an air pollutant. Yes, it is a greenhouse gas, but so is water vapor. Like oxygen, carbon dioxide is a clear, odorless gas and an essential component of clean air on planet Earth.

The auto emissions that chiefly impact air quality are nitrogen oxides and volatile organic compounds, which form ozone smog in the presence of heat and sunlight, and soot particles from incomplete combustion. Due to advances in emission control technology and fuels, all new cars and trucks today are practically zero-pollution vehicles.

That is evident from any number of the Environmental Protection Agency webpages posted during previous administrations. Compared to 1960s vehicle models, today’s new cars and light trucks are roughly 99 percent cleaner for common air quality contaminants (hydrocarbons, carbon monoxide, nitrogen oxides, and particulates). A chart produced by the U.S. Auto Alliance quantifies this progress to the tenth of a percent:

With respect to smog-forming emissions, today’s cars are already 99.4 percent cleaner than vehicles manufactured before 1968. By 2025, vehicles will be even cleaner and air quality will continue to improve regardless of whether courts uphold or reject the SAFE rule. The SAFE rule will have negligible or even slightly positive impacts on U.S. air quality, for four reasons.

First, as American Enterprise Institute economist Benjamin Zycher explains, the SAFE rule’s relaxation of model year 2020-2026 fuel economy standards “does not change the vehicular emissions limits for such conventional (‘criteria’) pollutants as carbon monoxide or nitrogen oxides. Those emission standards are defined in grams per mile, not grams per gallon, so that a relaxation of mileage requirements would not affect those emissions.”

Second, as the SAFE rule argues, relaxing fuel economy standards will make new cars more affordable to middle-income households. Any policy that facilitates replacing older with newer vehicles promotes air quality, because new cars are cleaner as well as safer and more fuel efficient.

Third, the EPA’s latest standards for nitrogen oxides, organic emissions, and particulates, known as Tier 3, run from 2017-2025. The Tier 3 program is projected to help reduce ambient levels of soot and smog through 2030. Nothing the Trump administration is proposing would stop that.

Fourth, when applying for the 2013 waiver for its Advanced Clean Car program, which includes the zero-emission vehicle (ZEV) mandate, the California Air Resources Board (CARB) noted there is “no criteria emissions benefit” from the ZEV requirements beyond those achieved by the state’s Low Emission Vehicle III (LEV III) program (78 FR 2122). The SAFE rule leaves California’s LEV III standards intact.

CARB did project an upstream emissions benefit to the extent that the ZEV mandate reduces petroleum consumption and, thus, emissions associated with petroleum refining. However, I am unable to locate CARB’s estimates of the expected reductions in refinery emissions and the purported health benefits thereof.

In any event, refineries are already regulated under the Clean Air Act’s new source performance standards program, hazardous air pollutant program, and national ambient air quality standards program. Moreover, California remains free to promote electric vehicles through tax credits, appropriations, and the state’s cap-and-trade program. Thus, the SAFE rule’s impact on refinery emissions is likely to be negligible.

Will the SAFE Rule Increase Asthma Rates and Attacks?

Some witnesses and subcommittee members claimed the SAFE rule would harm people with asthma, especially children. Such allegations are unfounded. To repeat, carbon dioxide, the only “pollutant” increased by the rollback, is not an air quality contaminant. Moreover, it is far less clear than commonly supposed that air pollution is a significant factor in asthma prevalence or exacerbations.

Correlation does not prove causation. However, there must be correlation to reasonably suspect causation. In the case of air pollution and asthma, there are significant negative correlations.

First, as is often justly lamented, U.S. asthma prevalence rates have been increasing since 1980. However, U.S. air pollutant emissions and concentrations have been declining since 1970. Between 1970 and 2018, the combined emissions of the six common pollutants (PM2.5 and PM10, SO2, NOx, VOCs, CO and Pb) dropped by 74 percent. More importantly, concentrations of asthma-triggering pollutants—O3, SO2, NO2, PM2.5—declined by significant percentages.

Ozone (O3) levels are highest during the summer because people drive more and heat promotes ozone formation. Consequently, we would expect asthma exacerbations to be highest during June-August. In fact, exacerbations are highest during September-November. Consider these excerpts from two recent studies.

(Wisnieski, et al. 2016): An annual peak in asthma exacerbations was observed during the fall months (September through November) among children who lived in Charlottesville, Virginia, as well as throughout the state of Virginia. An increase in exacerbations, which peaked in November, was observed for exacerbations among children who lived in Tucson, Arizona, and Yuma, Arizona. . . . A nadir in the frequency of attacks was observed during the summer months in all the locations (emphasis added).

(Teach, et al. 2015): While asthma exacerbations can occur at any time during the year, seasonal patterns exist, and in children, exacerbation rates are highest in the fall and lowest in the summer (emphasis added).

None of this is to say that high levels of air pollution don’t harm people or trigger asthma. The point rather is that air pollution does not appear to be a factor increasing asthma prevalence in recent decades or in seasonal asthma exacerbations, because air pollution and asthma are negatively correlated.

There is as yet no consensus on why asthma rates have gone up as air pollution has gone down. The answer may lie in exposures to indoor allergens, particularly cockroach dust, rodent allergens, and mold, which are significant contributors to asthma, especially in women and children, who spend up to 90 percent of their time indoors.

Do Refinery Emissions Cause Asthma and Cancer in Detroit?

At the hearing, Rep. Rashida Tlaib (D-MI) blamed the local Marathon Petroleum refinery for causing asthma attacks in her district. She seemed to imply that California’s motor vehicle standards would alleviate asthma in Detroit by accelerating the refinery’s demise.

Rep. Tlaib’s accusation is implausible for three reasons. First, according to Michigan Department of Environmental Quality data, the Detroit refinery is responsible for only 3 percent of air emissions within the two-mile radius of the facility.

Second, the refinery’s criteria pollutant emissions have decreased by almost 80 over the past 20 years, and have been well below permitted levels for the past 14 years. Thus, if local asthma rates are increasing, it is difficult to see how the refinery could be responsible.

Third, the state with the largest number of refineries, gas producing wells, and active oil wells is Texas, and Texas is tied with South Dakota and Minnesota in having the lowest asthma rate in the nation (7.3 percent). In contrast, New England states, which have no petroleum refineries, have significantly higher asthma prevalence rates than Texas. For example, Vermont, which has no refineries and no fossil fuel production, has one of the nation’s highest asthma prevalence rates (11.5 percent).

Do Refinery Emissions Cause Cancer in Detroit?

Rep. Tlaib also suggested the Marathon refinery is causing cancer in her district. That, too, is implausible.

The Detroit Marathon facility has a refining capacity of 140,000 barrels per day. The Texas Gulf Coast is home to the nation’s three largest refineries: Motiva Enterprise’s Port Arthur refinery (680,000 bpd), Marathon Petroleum’s Galveston Bay refinery (586,000 bpd), and ExxonMobil’s Baytown refinery (560,500 bpd). Centers for Disease Control and Prevention data show that the congressional districts in which those facilities are located (Texas 2, 14, and 29) all have significantly lower cancer rates than Rep. Tlaib’s district (Michigan 13).


Why do climate campaigners so often resort to scare-pollution rhetoric? One reason is that it diverts public attention from the abysmal disproportion between the alleged climatic benefits of their so-called solutions and the costs.

A more fundamental reason, though, is that smearing all who oppose their agenda is what progressive politicians and activists do. They cannot be talked out of demonizing fossil fuels, but they can be beaten at the polls. To that end, it is helpful to reassure the public that keeping energy affordable and making new cars more affordable will not degrade air quality, trigger asthma attacks, or give people cancer.