Multilevel Interventions and Co-Benefits

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Headshot of Anne Grossman, MD, FACP · Assistant Professor, Medical Education and Clinical Sciences
Anne Grossman
MD, FACP · Assistant Professor, Medical Education and Clinical Sciences
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Table of Contents

From understanding to action

Actions that simultaneously address climate change and create multiple health benefits beyond improved air quality.

Climate action is health action.

The most effective interventions create benefits across multiple domains: 

  • Air quality.
  • Climate.
  • Health.
  • Equity.
  • Economy.

Policy-level interventions: Emission reduction strategies

Transportation sector transformation

  • Mechanism: Elimination of tailpipe emissions (NOx, PM, VOCs, CO).
  • Evidence: California’s Zero Emission Vehicle program shows air-quality improvements in EV-dense areas.
  • Health modeling: Thousands of premature deaths prevented annually with widespread EV adoption.
  • Co-benefits:
    • Climate (reduced COâ‚‚).
    • Health (cleaner air).
    • Reduced noise pollution.
  • Per-capita emissions: 20–40% lower than individual vehicle use.
  • Co-benefits framework:
    • Climate: Reduced COâ‚‚ emissions.
    • Air quality: Less NOx, PM from vehicles.
    • Health: Physical activity (walking to/from transit).
    • Safety: Reduced traffic injuries.
    • Equity: Transportation access for all income levels.
  • Emission reduction: Each car trip replaced by bike = zero emissions.
  • Multiple health co-benefits:
    • Cardiovascular fitness from cycling/walking.
    • Mental health benefits.
    • Obesity prevention.
    • Reduced traffic injuries (protected infrastructure).
  • Evidence: Cities investing in cycling infrastructure show measurable population health improvements.

Energy sector transitions

Casey JA, Karasek D, Ogburn EL, Goin DE, Dang K, Braveman PA, Morello-Frosch R. Retirements of Coal and Oil Power Plants in California: Association With Reduced Preterm Birth Among Populations Nearby. Am J Epidemiol. 2018 Aug 1;187(8):1586–1594. doi: 10.1093/aje/kwy110. PMID: 29796613; PMCID: PMC6070091.

  • Within 5 km of closed coal/oil plants: 20% reduction in preterm birth.
  • Also decreased cardiovascular and respiratory hospitalizations.
  • Lower childhood asthma rates.
  • Key finding: Health benefits often exceed economic transition costs.
  • Wind, solar, geothermal: Zero operational air pollution.
  • Distributed solar: Reduces need for peaking power plants (often dirtiest).
  • Grid-scale batteries: Enable clean energy storage and dispatch.
  • Co-benefits:
    • Energy independence.
    • Job creation.
    • Stable prices.

U.S. Clean Air Act (1970–2020): 50-Year Track Record

  • 77% reduction in aggregate emissions of six common pollutants.
  • 230,000 early deaths prevented annually (EPA estimates).
  • Economic benefits: $30 in benefits for every $1 spent (30:1 ratio).
  • Achieved despite:
    • Population growth.
    • Economic growth.
    • Increased vehicle miles traveled.

Key lesson

Demonstrates that air-quality regulations are both feasible and highly cost-effective.

Population-level cardiovascular benefits of pollution reduction

A recent meta-analysis of 22 studies found that population-based strategies reducing both environmental pollution and unhealthy lifestyles were associated with a 48% decrease in the incidence of coronary artery disease (CAD)—demonstrating the profound cardiovascular benefit achievable through combined environmental and lifestyle interventions.

This reinforces the "climate action is health action" framework: Policies targeting air pollution deliver direct, measurable cardiovascular benefits at the population level.

Sagheer U, Al-Kindi S, et al. JACC: Advances, 3(2):100805. 2024. doi: 10.1016/j.jacadv.2023.100805.

Community-level interventions

Urban planning and green infrastructure

  • Air filtration: Leaves capture PM (Nowak et al. 2006 quantified tons removed annually).
  • Temperature reduction: Shade and evapotranspiration mitigate urban heat island.
  • Reduced ozone: Cooler temperatures = less ozone formation.
  • Mental health benefits: Green space access associated with lower depression, anxiety.
  • Environmental justice note: Tree canopy inequitably distributed—wealthier neighborhoods have more.
  • LEED certification reducing building emissions.
  • Mixed-use development reducing vehicle miles traveled.
  • Pedestrian-oriented design encouraging walking.

Community resources during poor air quality

  • HEPA-filtered clean air rooms: Libraries, community centers provide refuge.
  • School outdoor activity policies: Based on AQI monitoring.
  • Community air quality monitoring: Local networks (PurpleAir) supplement official monitors.
  • Public health alerts: Text/email notifications for vulnerable populations.

Individual-level actions and clinical counseling

  • Screen for environmental exposures in patient histories.
  • Review air quality risks based on individual patient factors.
  • Prescribe protective behaviors:
    • Checking AQI.
    • Limiting outdoor activity.
  • Adjust medications preemptively during poor air quality days.
  • Connect patients to resources:
    • AirNow.gov.
    • Home filtration programs.
    • Cooling centers.
  • Check AirNow.gov daily; make it a habit like checking weather.
  • Limit outdoor activity when AQI >100, especially for vulnerable populations.
  • Time outdoor activities: Avoid afternoon hours on high-ozone days.
  • Keep windows closed, use HEPA filtration during poor air quality episodes.
  • Wear N95 masks during severe episodes (wildfire smoke, AQI >200).
  • Adjust medications: Increase controller medications, keep rescue inhalers accessible.
  • Telemedicine: Reduces travel during poor air quality.

Clinical script

The AQI today is orange, which means it can worsen asthma. For the next few days, avoid outdoor exercise, keep windows closed, and if you have a HEPA air filter use it—especially in the bedroom. If you must go outside, wear a well-fitted N95 respirator for protection.

Physician advocacy and healthcare sector leadership

In January 2026, the European Society of Cardiology, American College of Cardiology, American Heart Association, and World Heart Federation jointly stated:

“Integration of planetary and environmental health into cardiovascular care will be vital in reducing the burden of non-communicable diseases globally.”

This is not a fringe position—it is a formal mandate from the highest levels of your future profession. As physicians, you are being called upon to integrate environmental health into your clinical practice and to advocate for policy change.

Münzel T, Lüscher T, Kramer CM, et al. Global Heart, 21(1):3. 2026.

  • Trusted messengers on health impacts—physicians among most trusted professionals.
  • Can translate science into human health consequences.
  • Connect individual stories to policy needs. 
  • Medical societies provide evidence-based positions (ESC, ACC, AHA, WHF, AMA, AAP all have climate/air quality statements).

  • Political neutrality on health—air quality transcends partisan politics when framed as health issue.

Question: Co-benefits framework

A city is considering implementing a new electric bus fleet to replace diesel buses. Which of the following represents a co-benefit of this intervention beyond improved local air quality?

Reduced greenhouse gas emissions is a key co-benefit. This intervention creates multiple benefits simultaneously:

  • Air quality benefit: Elimination of diesel exhaust (NOx, PM2.5).
  • Climate benefit: Reduced COâ‚‚ emissions (typically 50–70% reduction per bus).
  • Health co-benefits: Quieter neighborhoods (reduced-noise pollution).
  • Equity benefit: Transit-dependent populations (often low-income) benefit from cleaner buses.
  • This demonstrates “climate action is health action”—interventions addressing climate simultaneously create immediate local health benefits.

 

Why other options are incorrect:

  • B, C: These are potential costs/challenges, not benefits.
  • D: This would be a negative outcome.

Activity 3: Multi-level intervention design

Effective physician advocacy requires understanding how health interventions operate at different levels—individual behavior, community infrastructure, and public policy. In this activity, you will review a real-world intervention proposal and apply the framework you have been learning to identify what is missing and strengthen it.

The proposal

Proposed intervention: Distribute free N95 masks to residents during high air quality index (AQI) days.
Intervention level: Individual.
Expected health benefits: Reduces inhalation of PM2.5 and other pollutants. People with lung conditions like asthma would benefit.
Climate co-benefits: Reduces emissions by encouraging people to stay informed about air quality.
Additional co-benefits: Raises public awareness about air pollution.
Potential barrier and solution: Masks may not fit all face sizes. This could be addressed by offering multiple sizes.

Step 1: Identify the weakest section

Proposal question 1

Which section of the proposal is most in need of improvement?

If you selected A: The health benefits section is somewhat underdeveloped—it does not name specific vulnerable groups like children, the elderly, or outdoor workers. However, there is a more fundamental flaw elsewhere in the proposal. Review the climate co-benefits section again.

If you selected B: Mask distribution is actually a reasonable example of an individual-level intervention, since it acts on individual exposure rather than the source of pollution. Consider whether another section contains a more substantive error.

If you selected C: Good catch. This is the most significant flaw. Distributing masks does not reduce greenhouse gas emissions at all—it is a protective measure that addresses exposure, not the source of pollution. A valid climate co-benefit would need to describe something that reduces the actual production of pollutants or emissions (for example, replacing diesel bus fleets, increasing urban tree canopy, or reducing industrial output). Keep this distinction in mind as you move forward.

If you selected D: Mask fit is a real practical consideration, but it is a minor logistical issue rather than a fundamental barrier to the intervention’s success or impact. More significant barriers might include cost sustainability, equitable distribution, or the fact that masking addresses symptoms of the problem rather than its source. Look again at the climate co-benefits section.

Step 2: Revise the climate co-benefits section

Now that you have identified the flaw, select the response that would best replace the climate co-benefits section of this proposal.

Proposal question 2

Which of the following is the most appropriate climate co-benefit to add to this proposal?

If you selected A: Reusability is worth noting as a sustainability consideration, but it is a minor point. The core issue is that mask distribution does not address the source of air pollution at all. A meaningful climate co-benefit should describe how the intervention (or a paired measure) reduces the actual production of greenhouse gases or pollutants.

If you selected B: Downstream advocacy is speculative and indirect. While health literacy can support civic engagement, this is not a co-benefit that can be attributed to the intervention itself. Climate co-benefits should be more directly mechanistic.

If you selected C: This assumes a causal chain (high AQI warning → people stay home → fewer car trips → lower emissions) that is not well supported and would be very difficult to measure. It also mischaracterizes the intent of the intervention. Speculative co-benefits can weaken a proposal’s credibility.

If you selected D: Correct. Intellectual honesty is an important part of proposal design. Mask distribution is an exposure-reduction strategy — it does not reduce emissions or address the source of pollution. Acknowledging this limitation and pairing the intervention with a complementary source-reduction measure (such as a low-emission zone policy) is both more accurate and more persuasive to policymakers and funders.

Step 3: Strengthen the proposal

One additional gap remains. The health benefits section names asthma but does not identify the full range of vulnerable populations.

Proposal question 3

Which of the following additions would most strengthen the expected health benefits section?

If you selected A: While air quality does have associations with mental health, this is not a primary mechanism for this intervention and would require its own evidence base to include credibly. Strengthening the core health benefits section is a higher priority.

If you selected B: Correct. Identifying vulnerable populations is essential to both the ethical framing and practical implementation of any public health intervention. These groups have higher baseline exposure (outdoor workers, low-income residents in high-traffic areas), higher physiological susceptibility (children, elderly, pregnant individuals), or reduced physiological reserve (those with existing cardiopulmonary disease). Targeted distribution to these groups also improves cost-effectiveness.

If you selected C: While true, this shifts the framing of the intervention away from air quality and could dilute the proposal’s focus. Cross-protective benefits can be noted briefly but should not replace specificity about air quality-related health outcomes.

If you selected D: This is incorrect. Vulnerability to air pollution is not evenly distributed. Proximity to pollution sources, time spent outdoors, housing quality, physiological factors, and pre-existing conditions all create meaningful gradients of risk across the population.

Step 4: Reflection

This part of the exercise will not be graded. It is an opportunity to consolidate your thinking.

Proposal question 4

Based on this activity, briefly describe one intervention you would propose for your own community or a community you are familiar with. What level would it operate at, and what is one limitation you would want to be upfront about?

You have completed Activity 3. The key takeaway from this exercise is that well-designed interventions are honest about what they can and cannot achieve. Masks reduce exposure—they do not reduce emissions. Pairing exposure-reduction strategies with source-reduction policies is both more effective and more defensible. These distinctions matter when you advocate for patients beyond the clinic.

Integrated case analysis

This integrated case analysis tests your ability to apply all four learning objectives to a realistic clinical scenario.

Tap the arrow to view the case.
Patient: Marcus, a 6-year-old boy.
Setting: Pediatric clinic, September.
Background: Wildfire smoke from fires 200 miles away has caused air quality to reach "unhealthy" levels (AQI 165, primarily PM2.5). The forecast shows this will persist for 3–5 days. Local news reports multiple wildfires burning in drought-affected forests.
Marcus presents accompanied by his mother with increased cough, wheezing, and shortness of breath over the past 24 hours. He has needed his albuterol rescue inhaler 4 times today (usually used <1 time/week). No fevers or chills.
He has a past medical history of Asthma (previously well controlled on low-dose inhaled corticosteroid). He plays soccer and had outdoor practice yesterday afternoon when the air quality was poor. Lives 300 meters from Highway 99; no air conditioning; windows typically open, parents are unfamiliar with AirNow.gov or AQI.

Case Question 1: Climate Air Quality Connection

Explain the relationship between climate change and the current air quality situation affecting Marcus. What mechanisms led to the elevated PM2.5 levels from wildfires occurring 200 miles away?

Climate change has created conditions that increase wildfire risk through rising temperatures and prolonged droughts, which dry vegetation and create more fuel for fires. The western United States has experienced a 4x increase in wildfire area since the 1980s due to these climate changes.

Wildfires produce massive amounts of PM2.5 (80–90% of smoke composition) along with other pollutants like carbon monoxide and VOCs. Wind patterns transport this smoke hundreds of miles from the fire source—in this case, 200 miles to Marcus’s location, where it accumulates and degrades local air quality for days. This demonstrates how climate change acts as a “threat multiplier” for air quality, creating exposure events far from the original source and affecting millions of people regionally.

Case Question 2: Pathophysiology

Describe the pathophysiological mechanisms by which PM2.5 from wildfire smoke is causing Marcus's asthma exacerbation. Include both airway-specific and systemic inflammatory responses.

PM2.5 particles deposit deep in Marcus’s airways where they trigger oxidative stress and release of inflammatory cytokines (IL-6, IL-8, TNF-α) from epithelial cells and alveolar macrophages. In his already hyperreactive asthmatic airways, this leads to bronchoconstriction, mucus hypersecretion, and increased airway inflammation. His baseline airway inflammation from asthma is compounded by the pollution-induced inflammation, amplifying the response beyond what would occur in a healthy individual. Additionally, ultrafine particles can cross into the bloodstream, causing systemic inflammation with elevated C-reactive protein and other inflammatory markers. The combination of local airway effects (bronchoconstriction, mucus plugging, epithelial damage) and systemic inflammation explains his acute symptoms of cough, wheeze, and shortness of breath, which requires frequent rescue inhaler use.

Case Question 3: Vulnerability

Marcus is particularly vulnerable to poor air quality. Identify at least three specific factors that increase his susceptibility compared to an average adult and briefly explain the biological or social basis for each.

Marcus has multiple vulnerability factors:

  1. Age: At 6 years old, his respiratory system is still developing with ongoing alveolarization, making him more susceptible to permanent damage from pollution exposure.
  2. Higher minute ventilation: Children breathe more rapidly and have substantially higher ventilation rates relative to body weight, meaning he inhales a higher dose of pollutants per kilogram than an adult.
  3. Pre-existing asthma: His baseline airway hyper-reactivity and inflammation means the same pollution exposure triggers a more severe response than in healthy individuals
  4. Outdoor activity: Playing soccer means increased ventilation during outdoor exposure, dramatically increasing his inhaled dose during practice.
  5. Proximity to Highway 99 (300m): Chronic traffic pollution exposure compounds acute wildfire smoke exposure.
  6. No air conditioning/windows open: Inability to reduce indoor exposure during poor air quality episodes. These factors combine biological vulnerability (age, asthma) with social/environmental vulnerability (housing, lack of protective resources).

Case Question 4: Interventions

Part A: What immediate individual-level protective measures would you recommend to Marcus's family for the next few days while air quality remains unhealthy?

Part B: And name ONE policy-level intervention that could reduce the frequency of such air quality episodes in the future and identify TWO co-benefits of this intervention (one health co-benefit beyond improved air quality, and one climate co-benefit).

Part A (Individual-level): Recommend that Marcus stay indoors as much as possible with windows closed for the next 3–5 days until AQI improves. If the family has or can afford a HEPA air filter, use it in Marcus’s bedroom to reduce indoor PM2.5 levels. Cancel soccer practice and all outdoor activities until AQI returns to yellow or green (below 100). Keep his rescue inhaler readily available and consider using it prophylactically before any necessary outdoor exposure. Have the family download the AirNow.gov app or visit the AirNow website daily to track when air quality improves. Consider temporarily increasing his controller medication dose in consultation with your attending physician. If symptoms worsen despite these measures (increased work of breathing, inability to speak in full sentences, persistent symptoms despite rescue inhaler), seek immediate medical attention.

 

Part B (Policy-level):

  • Policy intervention: Climate change mitigation through greenhouse gas emission reductions, achieved through transitioning to renewable energy (solar, wind) and electric transportation. 
  • Health co-benefit: Immediate local air quality improvements from reduced fossil fuel combustion—this means fewer respiratory and cardiovascular hospitalizations, decreased asthma exacerbations, and lower mortality from air pollution even before wildfire frequency changes.
  • Climate co-benefit: Reduced COâ‚‚ emissions slow global warming, which reduces the frequency and intensity of the droughts and high temperatures that create wildfire conditions— addressing the root cause of events like Marcus is experiencing.
  • Additional co-benefits could include job creation in the clean energy sector, energy independence reducing geopolitical risks, and economic savings from avoided healthcare costs.

Key takeaways

Takeaway 1

The AQI is a clinical vital sign for exposure. Most day‑to‑day clinically meaningful outdoor air quality risk is captured by PM2.5 and ground‑level ozone, and students should know how to use the AQI categories to counsel patients.

Takeaway 2

Air pollution worsens cardiopulmonary disease through inflammation and vascular stress, and risk is not evenly distributed. Students should be able to explain, at a high level, how inhaled pollutants drive airway inflammation and systemic vascular effects, identify who is most vulnerable, and distinguish biologic vulnerability from exposure disparity (environmental justice lens).

Takeaway 3

Clinicians have an evidence‑based action set at three levels (patient, community, policy), and many actions create co‑benefits. Students should be able to do:

  1. Brief exposure history and counseling.
  2. Recommend practical protections (HEPA, respirator when appropriate).
  3. Name one upstream intervention that reduces emissions and improves health equity.
Extended reading: Low-emission zones and congestion pricing
  • London: 20–30% reduction in PM2.5 and NOâ‚‚ in ultra-low emission zone.
  • Stockholm: 10–15% improvement in air quality.
  • Milan: Decreased pediatric asthma hospitalizations in zone.
Extended reading: Advocacy opportunities for physicians
  • Testify at public hearings on air quality standards, transportation plans, energy policy.
  • Write op-eds and letters to editors connecting environmental policies to patient health.
  • Join medical society committees on climate and environmental health.
  • Support clean energy/transportation policies through professional organizations.
  • Healthcare sector decarbonization: Hospitals reducing their own emissions.
  • Community partnerships: Work with environmental justice organizations.

Image credits

Unless otherwise noted, images are from Adobe Stock.

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