TL;DR — A variety of air quality policies and interventions have been implemented since the first modern air pollution legislation was passed in the 1950s, with oversight differing widely between countries and regions. While top-down approaches to air quality legislation — national-scale policies such as the Clean Air Act in the United States, and global recommendations for maximum air pollution such as those provided by the WHO’s air quality guidelines — have been effective in reducing background concentrations, in recent years we have seen a shift in focus from large-scale interventions to more targeted efforts to improve localized air quality. These policies — enabled by the availability of more targeted air pollution measurement technology — may target categories of air pollution based on the specific pollutant of concern, the source of the pollution, or the region facing the highest impacts. Some forward-looking legislation also looks to incorporate the co-benefits of climate change mitigation that come with improved air quality to better quantify the benefits of environmental policies.

A history of air quality interventions and policies

Since air quality was recognized as an issue with bouts of smog observed in cities during the period following the Industrial Revolution, governments have worked to control air pollution through a variety of policies and regulations.

The image above displays the lethal fog that occurred in Donora, Pennsylvania in 1948. The air pollution, linked to the emissions of the Carnegie Steel factory established in the town, killed 20 people and harmed many more, sounding the alarm about the dangers of air pollution to human health. (Image source: Library of Congress)

In the United States, the Air Pollution Control Act of 1955 was the first federal legislation involving air pollution, and it provided funding for federal research. Following this, the Clean Air Act of 1963 was the first federal legislation on air pollution control, creating a program to research different ways to monitor and control air pollution.

The Clean Air Act of 1970 — which builds on the air pollution control established with the Clean Air Act of 1963 by creating comprehensive federal and state regulations — as well as its later amendments now set the basis for air pollution regulation in the United States, particularly through the establishment of the National Ambient Air Quality Standards (NAAQS). For more information on this act and how it set into motion a long process of improving the nation’s air quality, read our blog regarding air quality monitoring in the United States here.

Globally, a variety of air quality standards and policies exist. In the European Union, legislation from the European Environmental Agency (EEA) and the UK Clean Air Act of 1956 established air quality regulatory standards.

According to 2020 numbers, about two-thirds of countries have national ambient air quality standards. However, only 57 of these 124 countries continuously monitor air quality, and 104 countries have no infrastructure to monitor air quality. There is still a long way to go to ensure sufficient air quality monitoring infrastructure and regulation exist globally — a necessary step for decreasing air pollution worldwide.

The World Health Organization (WHO) sets recommended guidelines for permissible levels of different air pollutants. These guidelines are not enforceable, but science-based recommendations for countries to base their air quality regulations on. The first edition of the WHO guidelines for Europe was published in 1987, and the withstanding 2005 guidelines were updated just last year to more stringent levels, as we detail in our blog here.

Global and national-scale air quality interventions and policies

At the global level, the WHO’s air quality benchmark recommendations, while not regulatory standards, work as an air quality intervention meant to improve air quality transnationally. 

However, since the release of the previous WHO air quality guidelines in 2005, there has been a significant increase in evidence that demonstrates the vast harms of air pollution on human and environmental health  — currently estimated to account for 7-10 million premature deaths worldwide. These findings mean that the burden of disease associated with air pollution makes it just as dangerous as other global health risks, such as tobacco smoking and an unhealthy diet, and even more dangerous than car crashes based on the resulting mortality.

In 2021, the WHO released more stringent guidelines to motivate countries to target even lower levels of air pollution. These data-informed guidelines help policymakers in various countries make air quality legislation that can help protect the public from air pollution, and they specifically target known harmful air pollutants, including some that also are known to contribute to climate change

In 2019, more than 90% of the global population lived in areas where concentrations exceeded the 2005 WHO air quality guideline for long-term exposure to PM₂.₅. Countries with strong policy-driven improvements in air quality have often seen marked reduction in air pollution, whereas declines over the past 30 years were less noticeable in regions with already good air quality.”

For more information, see our blog detailing the WHO guidelines here.

The WHO guidelines serve as a target for countries implementing national-scale air quality regulations, such as the USEPA Clean Air Act, which extends both federal and state regulations across the United States to reduce emissions from both stationary and mobile sources of air pollution. The legislation also developed four major regulatory programs for stationary and industrial sources:

  • The National Ambient Air Quality Standards (NAAQS), that sets standards for six criteria air pollutants
  • State Implementation Plans (SIPs)
  • New Source Performance Standards (NSPS)
  • National Emission Standards for Hazardous Air Pollutants (NESHAPS)

By targeting specific sources and/or air pollutants, this legislation creates an overarching infrastructure for air quality regulation that examines air pollution at the state and federal levels. Later amendments to the legislation target air pollution sources in non-attainment areas to help address those areas with excessive pollution.

According to an EPA peer-reviewed study from 2011, the programs established by the 1990 Clean Air Act amendments are expected to yield benefits that vastly outweigh the costs of compliance. The study estimated a $2 trillion benefit in 2020, exceeding the costs by a factor of 30. This economic benefit is linked to the fewer air pollution-related illnesses that occur, lowering medical costs and lost workdays. 

The Clean Air Act 1990 Amendments prevent:

According to a USEPA study, the 1990 Amendments to the United States Clean Air Act prevent vast numbers of negative health outcomes, such as emergency room visits and mortality, along with lost work and school days, by decreasing air pollution. (Image source: EPA)

Air pollution regulations of traffic standards also exist at the federal level in the United States. Standards placed on heavy-duty truck emissions adopted in 2016 are estimated to cut over a billion tons of climate pollution and save hundreds of millions of dollars by 2035. By decreasing the emissions of particulate matter and smog-precursor pollutants, these standards also positively impact public health and benefit a wide range of stakeholders.

The shift toward regulating air pollution at the local scale

Though top-down approaches to regulating air quality have been effective in reducing background ambient air pollutant concentrations at the national or regional scale, these regulations — and the technologies used to measure compliance with them — leave gaps behind when it comes to addressing the local impacts of air pollution in zones with high concentrations. Policymakers must recognize how air pollution impacts public health at a more localized level — and what regulators can do to improve air quality at this level.

As air quality monitoring technology progresses to allow for more localized and specialized measurement of air pollutants, air quality policy has also been able to progress to target more specific locations, pollutants, and pollutant sources. These “next-generation air quality policies” can be bucketed into three categories:

  • Source-based policies 
  • Location-based policies 
  • Pollutant-based policies targeting "new" pollutants (i.e. those not included in the NAAQS or other traditional air quality regulatory frameworks)

Source-based policies

Source-based air pollution regulations are not a new concept entirely, but the increasing portability and cost-effectiveness of air quality measurement equipment means that governments can measure air pollution at the source more effectively than ever.

One example of an existing source-based regulation is the CAA's National Emission Standards for Hazardous Air Pollutants (NESHAP), which targets toxic air pollutants including mercury, polychlorinated biphenyls (PCBs), benzene, and volatile organic compounds (VOCs) originating from industrial sources known as “source categories”. These hazardous air pollutants targeted by the legislation are those known or suspected to cause cancer or significant adverse effects on human or environmental health. The regulation covers both:

  • Major sources, or those which have the potential to emit more than 10 tons per year of a single HAP or 25 tons per year of any combination of HAPs
  • Area sources, or those which have the potential to emit less than 10 tons per year of a single HAP or 25 tons per year of any combination of HAPs, including many small businesses

Due to the ability to cost-effectively place air sensors in highly-targeted and strategic locations, air quality regulators can now target specific air pollution sources to reduce emissions directly at their origin. One such type of regulation is traffic standards, targeting vehicular emissions — such as California’s Sustainable Freight Action Plan, which set the goal of using zero- or near-zero emissions equipment to transport freight. 

Another example of source-based regulation is the implementation of Low Emission Zones (LEZs), such as London’s Ultra Low Emission Zone, which looks to minimize air pollution by charging drivers with the most polluting vehicles a fee to enter. The high-density network of Clarity Node-S devices installed across London as part of the Breathe London program will provide invaluable data points for measuring the efficacy of this highly-targeted policy. 

A USC study looked at which air quality policies of the past 20 years have been most effective in reducing air pollution in southern California. Because nitrogen dioxide and particulate matter are closely linked with primary emissions from vehicle exhaust, power plants, industry, ships, and trains, the regulations targeting these specific sources have resulted in significant decreases in air pollution. 

This study found that the most effective interventions have reduced on-road emissions, with nitrogen dioxide decreasing by 28% to 53% in communities from San Luis Obispo County to San Diego County. Particulate matter similarly decreased by 13% to 54% across these communities, and those decreases in ozone were slightly less pronounced, with 12% to 27% reductions.

Gathering high-resolution air quality data from sensor networks can also help inform future development plans by allowing researchers to identify what specific sources are contributing most heavily to air pollution in a given area — a practice known as source apportionment. For example, this study used a network of air sensors to provide insight into the contributions of London Heathrow Airport to overall air pollution in the area. 

The image above displays the location of sensors deployed at the London Heathrow Airport with red tags, as well as the reference monitoring station indicated with a blue tag, relative to the airport terminals. By placing sensors at various points around the airport, high-resolution air quality data can be collected to inform the researchers’ conclusions and subsequent decision-making made based on this data. (Source: Popoola et al., 2018)

Air pollution measurements from the air quality sensors enabled researchers to distinguish airport emissions from other sources, such as long-range transport, demonstrating that emissions from the airport did not contribute significantly to the concentration of particulate matter or nitrogen dioxide in the area. By developing an air pollution model based on this data, they were able to conclude that despite the planned construction of an additional runway at LHR that would increase airport-related NO2 emissions, improvements in road traffic fleet emissions would likely more than offset this increase. 

This approach of using air sensors for source apportionment has broad applicability for a wide range of environmental monitoring applications and air quality interventions, especially in complex air quality environments such as developing megacities. By leveraging air quality measurements from sensors, governments can cost-effectively identify the policies and interventions that will have the greatest impact on air quality and other environmental issues such as greenhouse gas emissions.

In fact, by considering the climate change co-benefits that come with reducing air pollution, stakeholders can garner greater support for environmental policies that work towards alleviating both environmental crises. To learn more about these co-benefits and the exciting potential for dual air quality and climate change action, read our blog here.

Location-based policies

Air quality is a dynamic phenomenon that is rarely uniform across an entire region. Location-based air quality regulations recognize that far-reaching federal or state air quality interventions can often overlook areas that experience disproportionately poor air quality. The advent of cost-effective, accurate air sensors means that these areas no longer need to face underrepresentation when it comes to air policy measurement and regulation.  

One example of governments leveraging new technologies to better measure and manage air pollution at the local scale is the Breathe London community programme, funded by the Mayor of London and Bloomberg Philanthropies.

The program has awarded dozens of free Clarity Node-S devices to local London communities, providing Londoners that traditionally face poor air quality and lack of access to green space — often low-income or ethnic minority communities — access to real time-air quality data.

This next phase of development of the Breathe London network really puts air quality monitoring into the hands of London’s communities. We’re genuinely excited to see the inspiring and impactful uses to which these monitors will be put by Londoners to improve the health and environment of their neighbourhoods and our city."

— Dr. Ben Barratt, Reader in Environmental Exposures & Public Health and Deputy Director of the Environmental Research Group at Imperial College London

Another location-based policy leveraging new air quality measurement equipment is California’s AB 617 legislation, which was introduced in 2017 and is intended to address air pollution impacts in environmental justice communities through the involvement of local air districts and the California Air Resources Board (CARB). 

Communities overburdened by air pollution are the same communities that historically have been subject to discriminatory policies like redlining, highway construction and urban renewal projects, and in neighborhoods with limited access to health care, healthy food, quality education and outdoor spaces, all compounding the health burdens.”

Environmental justice activists argue that California’s cap-and-trade program and top-down approach to improving air quality have allowed polluters to continue to pollute these neighborhoods, and other legislation such as the Clean Air Act only works to lower air pollution at the regional level, thereby missing these localized disparities. Thus, the Community Air Protect Program (CAPP) was created by CARB to implement AB 617, establishing grants for community air quality monitoring projects.

The city of Richmond, California has long suffered from environmental damage and poor air quality due to a Chevron refinery located in the community. Groundwork Richmond, an environmental justice organization working to mitigate the negative impacts that poor air quality has on human and environmental health, applied for funding under AB 617’s Community Air Grants to install low-cost air quality sensors in their community, empowering residents to fight back against air pollution. 

AB 617 is still a newer piece of legislation, so its effectiveness is not yet known. Critics have pointed out that there is a long bureaucratic process involved in carrying out the community monitoring plans that may limit the legislation’s overall impact. Some have also questioned the enforceability of the air pollution reduction plans that are created and the extent to which they will lead to cleaner air in these communities.

Read our blog here for more information on the importance of improving air quality in environmental justice communities.

Location-based air quality interventions can also target specific regions that suffer from disproportionately poor air quality. For example, in the Western Balkans, a large percentage of people use solid fuels to heat their homes in the winter, causing certain cities in the region — such as Sarajevo, Skopje, and Sofia — to be some of the most polluted cities in the world. Those residents in the region are estimated to lose 13 to 16 months of their lives to air pollution.

Another study looking at the region found that 16 outdated coal power plants cost the economies and healthcare systems of Balkan countries between 6.1 and 11.5 billion euros each year.

Though not technically a regulation, the Canton of Sarajevo in Bosnia and Herzegovina implemented a decarbonization strategy that is working to eliminate the use of coal in homes and government buildings by 2030. The intervention is meant to build the foundation for future investment in low-carbon residential buildings, thereby setting the stage for development that is friendly to the air.

To target other instances of localized air quality issues, cities around the world are leveraging air sensors and other new forms of air pollution measurement technology to evaluate the efficacy of development initiatives known as “Clean Air Action Plans”. For example, the Kampala Capital City Authority (KCCA) Kampala, Uganda, launched its Clean Air Action Plan earlier this May during Air Quality Awareness Week. The plan was based on several years of data from their Clarity Sensing-as-a-Service air quality monitoring network

Low-cost sensors can be used to support air quality interventions in areas that have traditionally not had access to monitoring by providing more affordable, flexible, and scalable monitoring technology that can be employed for the location’s specific needs, such as in economically developing countries and underrepresented communities. To learn more about how low-cost sensors have been used to establish air quality monitoring networks in developing nations, read our blog here.

Pollutant-based regulations

Air quality policies and interventions typically target specific air pollutants known to be especially harmful to human and environmental health. In the United States, the Clean Air Act’s NAAQS identifies six criteria pollutants — ozone, particulate matter, lead, carbon monoxide, sulfur oxides, and nitrogen oxides — as harmful air pollutants whose emissions should be lowered. 

As our understanding of the health impacts of different air pollutants has progressed over the 50 years since the NAAQS were published, new regulations are beginning to emerge. Additional pollutants have been identified as particularly harmful, and improvements in air monitoring technology are making it feasible to measure — and therefore to regulate — a much wider range of harmful pollutants, including some that previously went unmonitored. 

For example, more than a dozen U.S. states including California, Oregon, Kentucky, and Texas have adopted comprehensive state and local-level strategies to address air toxics such as benzene, hydrogen cyanide, chromium, and ethylene oxide.

The newest such law, HB22-1244, was passed earlier this month in Colorado, instructing state regulators to develop a plan for monitoring and regulating 188 ‘air toxics'. In Colorado, the compounding effects of wildfire smoke during wildfire season, in addition to other sources of air pollution like industry, create some of the worst air quality in the country, and this bill drives real progress in protecting the health of communities impacted by air toxins.

The bill identifies toxic air pollutants based on how they impact human health, especially in the communities where they are being emitted, causing vast negative effects on health. The bill primarily works to:

  • Establish publicly available, annual values of toxic emissions from sources across the state
  • Strengthen air toxic monitoring, especially by prioritizing monitoring in those communities that are being disproportionately impacted
  • Use input from the public to identify priority toxics based on residents’ concern
  • Set health-based air quality standards for each priority air toxic identified

Another example of successful pollutant-based policies — one that was feasible with last century’s technology — is the regulation of sulfur dioxide and nitrous oxide emissions from the power sector that contribute to acid rain in the United States. The program targeting sulfur dioxide sets a permanent cap on the total amount of SO2 that may be emitted in the country. 

The Acid Rain Program (ARP) was the first national cap-and-trade program in the country, creating a system to incentivize polluters to reduce their emissions using market-based incentives. The program allows polluters to choose the most cost-effective way to reduce their emissions to meet these environmental goals. 

Conceptualizing the potential impacts of air quality interventions

With the vast range of air quality interventions and policies that have been enacted to control air pollution and improve the air, it is important to measure their effectiveness and determine which solutions are most impactful.

One study aimed to do so by looking at how future air quality would look under different air pollution policy scenarios. By comparing a “without air pollution policies” scenario (one where there are no dedicated policies to air pollution control), a scenario based on existing the existing 2018 legislature, and a “clean air” scenario with extensive air quality interventions, we can gain insight into how the future state of the air may look — depending on how we regulate it.

The “clean air” scenario involves a combination of ambitious environmental policies related to air pollution, energy and climate, agriculture, and food. The scenario also involves a full implementation of the best available technologies to control and reduce emissions with the goal of global long-term sustainability, including decarbonization strategies that would achieve the Paris climate accord and keep global temperature increases below 2°C. The study authors do note that these policies would require significant political support to become a reality.

The figure above shows the billions of people that are impacted by each air quality policy outcome, from having no air quality interventions in place (represented by gray), to the protection under the 2018 legislation (represented by dark blue), to the further public health benefit that would be afforded by additional air pollution, climate, energy, agricultural, and food policies (represented by light blue, yellow, green, and orange, respectively). (Image source: Amann et al., 2020)

The outcomes of the three scenarios are starkly different. Under the 2018 legislature scenario, particulate matter levels coming from anthropogenic sources would decrease below their 2015 levels in Europe, North America, and North and East Asia by 2040, increasing the percentage of the global population that lives in areas in accordance with the 2015 WHO guidelines. 

However, PM concentrations would increase in other regions, where anthropogenic sources of pollution would increase by 60% in Africa and 30% in the Middle East. 

In contrast, under the “clean air” scenario, there would be significant cuts in population-weighted fine particulate matter levels, from 5 µg m−³ in Europe and the Americas, to 15 µg m−³ in Asia, to 20 µg m−³ in Africa and 30 µg m−³ in the Middle East. The 23% of the global population that would live in areas that comply with the 2015 WHO guidelines in the 2018 legislature scenario would increase to 56% of the global population under the “clean air” scenario.

This scenario also demonstrates a 40% lower level of CO2 emissions by 2040 than in the 2018 legislature scenario as well as a 33% lower level of methane and a 90% lower level of black carbon. Population exposure to PM2.5 from anthropogenic sources would decline by about 75% relative to 2015, or by 80% compared to a future without additional policies.

To learn more about the link between air quality and climate change and how policies that consider the co-benefits of addressing these two environmental crises simultaneously, read our blog on the co-benefits of improved air quality.

In the figure above, the emissions of sulfur dioxide, nitrous oxides, primary fine particulate matter, and ammonia (NH3) are displayed, assuming effective implementation of the air quality interventions under the 2018 legislature scenario. The dashed and dotted lines represent where these emissions would lie based on having either no air pollution policies and the “clean air” scenario with ambitious air quality interventions. (Image source: Amann et al., 2020)

The study demonstrates the stark differences in what air future air quality might look like based on the type and degree of air quality policies in place. The extensive air quality, climate, energy, and agriculture policies in the “clean air” scenario would vastly decrease air pollution and significantly improve climate change mitigation compared to the 2018 interventions — that’s the scenario that has our vote!

The next generation of air quality policies and interventions will benefit from advances in air quality measurement technology

A wide variety of air quality policies and interventions have been implemented, with varying degrees of success. Looking back to the past 50 to 70 years of air quality policy helps us understand which policies have had a measurable impact on air quality — while looking forward at what policies and programs may be possible with new air quality measurement technology helps us envision a future where clean air is a reality for all!

While large-scale air quality policies such as the Clean Air Act have seen the improvement of air quality on larger state and federal levels, there is a significant need for more targeted policies that examine air quality at a higher resolution  — and alleviate the burden that currently exists for areas and communities that suffer from disproportionately high levels of air pollution, especially due to air pollution sources in their neighborhoods. With the rapid technological innovation taking place in the air quality industry, it is becoming increasingly possible — and cost-effective — to use air sensors to do so. 

In this blog we covered three ways new air quality measurement equipment such as air sensors are making the future of air quality regulation possible: 

  • Source-based regulations, targeting specific sources of pollution such as industrial facilities
  • Location-based regulations, where the air quality of a highly targeted zone is closely monitored and regulated
  • Pollutant-based regulations, which target pollutants that were not feasible to measure and regulate with last century’s technology

As air quality interventions evolve, we are thrilled to see the forward-looking policies that emerge thanks to advancements in air pollution monitoring equipment! 

Interested in setting up a network? Get in touch with our team to learn more about our Sensing-as-a-Service solution for governments, businesses, and community organizations!