Air pollution traits and US environmental coverage

Joseph S. Shapiro 02 December 2021

Within the Sixties and Nineteen Seventies, concern for US environmental high quality grew quickly. This progress had many causes, together with an oil spill off the coast of Santa Barbara, pictures of Earth taken from area, and a hearth on the Cuyahoga River in Cleveland. Spurred on by these issues, the federal authorities handed a slate of environmental laws within the early Nineteen Seventies, together with the Clear Air Act, Clear Water Act, Secure Consuming Water Act, and plenty of others. These legal guidelines had huge bipartisan assist.

A half century has handed since enactment of those legal guidelines, making it an excellent time to evaluate what has been realized from 50 years of environmental coverage and financial analysis. A number of research have summarised what analysis and policymakers have realized about particular particular person legal guidelines or pollution (Olmstead 2010, Currie and Walker 2019, Schmalensee and Stavins 2019, Keiser and Shapiro 2019b).

In a latest evaluate, I search to supply a broad overview of air pollution traits, coverage impacts, and distributional penalties, which is perhaps neglected in a single analysis paper or when analyzing a single coverage, pollutant, or methodology in isolation (Shapiro 2021). Within the evaluate, I assess the proof for 4 hypotheses:

  • Speculation 1: Air air pollution, consuming water air pollution, and floor water air pollution have declined considerably during the last a number of many years, though CO2 emissions haven’t.
  • Speculation 2: Environmental coverage explains a big share of long-term decreases in air and water air pollution.
  • Speculation 3: Air and consuming water insurance policies have tended to supply advantages that exceed their prices; the proof for floor water is way much less clear.
  • Speculation 4: Whereas the distribution of air pollution throughout social teams is unequal, market-based insurance policies and command-and-control insurance policies shouldn’t have systematically completely different results on the distributions of environmental outcomes. 

I additionally spotlight latest improvements in strategies and knowledge which have improved researchers’ skill to check these hypotheses. These advances embody using administrative knowledge on environmental items; use of statistical cost-benefit checks; a concentrate on essential however understudied insurance policies; extra subtle fashions of how air pollution emissions in a single location have an effect on ambient air pollution focus in different areas (i.e. air pollution transport); micro-macro frameworks that mix detailed knowledge on particular person corporations and households with macroeconomic fashions of the whole financial system; and a concentrate on how coverage impacts the distribution of environmental outcomes, significantly for low-income communities and communities of color. I talk about every speculation in flip.

Speculation 1: US air, consuming water, and floor water air pollution are declining, although CO2 emissions usually are not

Knowledge collected during the last half century reveal giant and sustained declines in each air pollution emissions and ambient concentrations. Proof is clearest for the pollution that the Clear Air Act, Clear Water Act, and Secure Consuming Water Act primarily goal, although some proof suggests steep downward traits in different pollution as effectively. Determine 1 demonstrates this proof by displaying nationwide traits in ambient concentrations of carbon monoxide, a dangerous gasoline, over the interval 1980-2020.

Determine 1 Ambient concentrations of carbon monoxide within the US, 1980–2020

Supply: USEPA (visited 14 September 2021)

Determine 2 demonstrates this sample through the use of knowledge on the share of US waters which can be protected for fishing, in accordance with organic and chemical air pollution requirements for fishing which can be broadly utilized in water high quality analysis.

Determine 2 Share of US waters that aren’t protected for fishing

Supply: Determine is reprinted from Keiser and Shapiro (2019b).

Speculation 2: Environmental coverage explains a big share of long-term decreases in air and water air pollution

One may think about many potential explanations for these decreases in air pollution, together with environmental coverage, outsourcing of soiled manufacturing overseas, innovation and productiveness progress, shifts within the financial system from manufacturing to companies, or shopper preferences shifting in direction of cleaner items. A number of research straight assess the significance of varied explanations and discover a central position for environmental coverage in explaining these traits. Shapiro and Walker (2018), for instance, discover that between 1990 and 2008, actual output from US manufacturing grew by a 3rd however air air pollution emitted from US manufacturing fell by half or extra. Microdata on agency manufacturing and a macroeconomic mannequin of commerce and air pollution counsel that more and more stringent regulation, relatively than commerce coverage or productiveness progress, finest explains this lower in air pollution. 

One other evaluation focuses on air air pollution from passenger autos and finds that the air air pollution emitted per mile pushed has fallen by greater than 99% since regulation started within the late Sixties (Jacobsen et al. 2021). One may think about a spread of causes for this environmental enchancment, together with productiveness progress in automobile manufacturing, gas financial system or gas content material requirements, or altering composition of autos attributable to shopper preferences. This evaluation finds that the Clear Air Act’s exhaust requirements for cell sources, which restrict the air pollution emitted per mile pushed for brand new autos, clarify between half and all of this lower in emission charges from passenger transportation.

Speculation 3: Air and consuming water insurance policies have tended to supply advantages that exceed their prices; the proof for floor water is way much less clear

Because the Reagan administration, the federal authorities has required profit–value analyses of enormous federal rules. A evaluate of dozens of those analyses carried out within the final 20 years finds that they estimate general profit–value ratios of 12.4 for air air pollution rules, 4.8 for consuming water air pollution rules, 3.0 for greenhouse gases, and 0.8 for floor water air pollution (Keiser and Shapiro 2019b). An earlier evaluate of such analyses carried out earlier than the 12 months 2000 additionally discovered excessive profit–value ratios for air and consuming water air pollution coverage however a decrease measured profit–value ratio for floor water air pollution coverage (Hahn 2000).

After all, one can query the accuracy of those analyses. Estimated air air pollution advantages rely closely on estimates of how ambient explicit matter concentrations have an effect on grownup mortality and on estimates of the worth of a statistical life – each of which have a spread of estimates. Estimates of advantages from floor water air pollution usually assume these advantages accrue primarily attributable to improved leisure alternatives, and usually assume the excessive stringency of consuming water regulation means there are few or no of bettering floor water high quality attributable to well being. As well as, estimates of prices in these regulatory analyses usually depend on engineering estimates of bodily management prices, which summary from essential financial forces like modifications in market energy, product high quality, and interactions with pre-existing taxes and distortionary insurance policies in markets for different items and companies. On the similar time, richer analyses of particular person insurance policies additionally have a tendency to seek out giant profit–value ratios for air air pollution coverage (e.g. Shapiro and Walker 2020) and far smaller profit–value ratios for floor water high quality coverage (e.g. Keiser and Shapiro 2019a).

Speculation 4: Whereas the distribution of air pollution throughout social teams is unequal, market-based insurance policies and command-and-control insurance policies shouldn’t have systematically completely different results on the distributions of environmental outcomes

Market-based environmental insurance policies embody air pollution taxes, cap-and-trade markets, and mixtures of those. Economists are likely to advocate market-based insurance policies as a result of they maximise air pollution discount for a given value, i.e. they’re value efficient. Environmental justice describes the honest remedy and significant involvement of all folks in design, implementation, and enforcement of environmental insurance policies, and achievement of excellent environmental high quality for all social teams. Environmental justice is without doubt one of the Biden administration’s prime two environmental coverage issues, alongside local weather change.

Some group and political teams have argued that environmental markets exacerbate environmental justice issues. Each Washington State’s carbon tax proposal (Initiative 732) and California’s cap-and-trade renewal (AB 398) confronted opposition from some progressive teams attributable to environmental justice issues (Brown 2020). Moreover, the Biden administration reportedly thought-about former California Air Sources Board head Mary Nichols to function Administrator of the Environmental Safety Company however stopped that consideration after environmental justice teams raised issues about her position in creating California’s cap-and-trade invoice (Davenport 2020).

A number of research have investigated how market-based environmental insurance policies have an effect on the distribution of environmental outcomes. Some analysis compares one cap-and-trade marketplace for nitrogen oxides within the Los Angeles area in opposition to the choice of a command-and-control coverage (Fowlie et al. 2012). The authors additionally analyse air pollution emitted from industrial sources and discover that the market had related decreases for various demographic teams. An evaluation of ambient air high quality finds that the market disproportionately benefitted high-income and white communities (Grainger and Ruangmas 2018). One other evaluation investigates how California’s cap-and-trade marketplace for CO2 affected air air pollution and finds that the market decreased air air pollution inequality between advantaged and deprived zip codes (Hernandez-Cortes and Meng 2021). Lastly, one other latest evaluation examines the Clear Air Act’s requirement that giant new soiled factories in polluted counties should buy the proper to emit air pollution from incumbents (Shapiro and Walker 2021). This requirement doesn’t seem to disproportionately relocate air pollution from or to low-income communities or communities of color.


These hypotheses inform a reasonably coherent story, with largely excellent news for coverage and society. Air and water air pollution are declining however greenhouse gasoline emissions usually are not as a result of environmental coverage has focused air and water air pollution however not CO2. These traits seem to supply giant internet advantages to US society and utilizing cost-effective market-based insurance policies doesn’t seem to have systematic implications for the equality of environmental outcomes.


Currie, J and R Walker (2019), “What Do Economists Must Say in regards to the Clear Air Act 50 Years after the Institution of the Environmental Safety Company?”, Journal of Financial Views 33(4): 3-26.

Davenport, C (2020), “Claims of ‘Bleak’ Environmental Justice Document Seem to Fell a Biden Favourite”, New York Instances, 18 December.

Fowlie, M, S P Holland, and E T Mansur (2012), “What Do Emissions Markets Ship and to Whom? Proof from Southern California’s NOx Buying and selling Program”, American Financial Evaluate 102(2): 965-93.

Grainger, C and T Ruangmas (2018), “Who Wins from Emissions Buying and selling? Proof from California”, Environmental and Useful resource Economics 71: 702-727.

Hahn, R W (2000), Reviving Regulatory Reform: A World Perspective, American Enterprise Institute–Brookings Joint Middle for Regulatory Research.

Hernandez-Cortes, D and Ok Meng (2020), “Do Environmental Markets Trigger Environmental Injustice? Proof from California’s Carbon Market”, NBER Working Paper 27205.

Jacobsen, M R, J M Sallee, J S Shapiro, and A A van Benthem (2021), “Regulating Untaxable Externalities: Are Automobile Air Air pollution Requirements Efficient and Environment friendly?”, mimeo, UCSD.

Keiser, D A and J S Shapiro (2019a), “Penalties of the Clear Water Act and the Demand for Water High quality”, Quarterly Journal of Economics 134(1): 349-396.

Keiser, D A and J S Shapiro (2019b), “US Water Air pollution Regulation over the Final Half Century: Burning Waters to Crystal Springs?”, Journal of Financial Views 33(4): 51-75.

Olmstead, S M (2010), “The Economics of Water High quality”, Evaluate of Environmental Economics and Coverage 4(1): 44-62.

Schmalensee, R, and R N Stavins (2019), “Coverage Evolution beneath the Clear Air Act”, Journal of Financial Views 33(4): 27-50. 

Shapiro, J S (2021), “Air pollution Developments and US Environmental Coverage: Classes from the Final Half Century”, NBER Working Paper 29478.

Shapiro, J S and R Walker (2018), “Why is Shifting? Environmental Markets and Environmental Justice”, AEA Papers and Proceedings 111: 410-14.

Supply hyperlink