How can the harmful effects of air pollution be mitigated?

Mitigating the Harmful Effects of Air Pollution

Structural emission reduction at the source is the most effective strategy to reduce air pollution's harmful effects on cardiovascular disease, respiratory illness, and mortality, but until achieved, clinicians should implement personal-level interventions including indoor air filtration, activity modification based on air quality indices, and use of N95/FFP2 masks during high pollution periods. 1

Systemic-Level Mitigation Strategies

Structural actions to reduce pollution emissions are ultimately necessary to achieve meaningful reductions in harmful exposures and their associated morbidity and mortality. 1 Historical evidence demonstrates that regulatory actions and emission control technologies in the United States were responsible for up to 15% of the increase in life expectancy over recent decades, primarily through reductions in particulate matter (PM) concentrations. 1 Similarly, large-scale programs providing clean cooking fuels to millions of households have successfully reduced inequalities in non-communicable diseases. 1

Health Impact Context

Air pollution represents a grave risk affecting nearly everyone globally and nearly every organ system in the body. 2 Approximately 7 billion people (92% of the global population) live in areas exceeding WHO Annual Air Quality Guidelines for PM2.5, while 3.6 billion people (47% of the global population) are exposed to household air pollution from solid fuel cooking. 1 The health impacts include:

• Cardiovascular effects: PM air pollution is associated with atherosclerosis progression, acute myocardial infarction, stroke, heart failure, arrhythmias, and cardiovascular mortality 1
• Respiratory effects: Ozone exposure causes respiratory disease exacerbation, COPD incidence and mortality, asthma exacerbation, and lung inflammation 1
• Systemic effects: Reduced oxygen delivery to tissues, increased oxidative stress and inflammation, and increased risk of respiratory virus infections 1

Personal-Level Mitigation Strategies for Patients

Indoor Air Quality Management

Room air filtration provides substantial improvements in PM levels within residences, schools, and workplaces, with evidence indicating improvements in blood pressure and measures of inflammation. 1 HEPA filter air purifiers can substantially reduce indoor PM2.5 concentrations over days to weeks and improve subclinical cardiopulmonary health. 3 Modeling studies suggest that population-level benefits of HEPA filtration would often exceed costs. 3

Specific indoor air quality actions include: 1

• Closing vehicle windows during transport
• Using cabin air filters
• Turning on air conditioning systems
• Maintaining closed windows during high pollution periods

Activity Modification Based on Air Quality

Patients should adjust outdoor activities using air quality indices that provide information on short-term variation in air quality. 1 Specific timing recommendations include: 1

• Avoid afternoon and early evening exercise when ozone (O3) peaks are highest
• Exercise in the morning when pollutant levels are typically lower
• Reduce exercise intensity during high pollution periods to limit total inhaled dose
• Relocate high-intensity training indoors when outdoor pollution levels are elevated

Detailed air pollution maps providing neighborhood-scale information on long-term exposures can be used to target cardiovascular disease treatment and exposure reduction efforts in those living in locations with highest exposures. 1

Respiratory Protection

N95, KN95, and FFP2 masks can remove 14-96% of PM depending on the mask type and correct use, especially when local PM concentrations are high. 1 Well-fitting N95 and equivalent respirators can reduce PM2.5 exposure, with several randomized crossover studies reporting improvements in subclinical cardiovascular health. 3

Important caveats: 1

• Masks may also reduce infection propagation
• Wearing masks can cause dyspnea in high temperatures, especially during physical activity
• The effectiveness of other face coverings is highly variable and depends largely on fit, unrelated to cost 3

Acclimatization Protocols

For individuals who cannot avoid exposure (such as athletes), arriving 4-7 days in advance of competition in areas with elevated pollution may help mitigate acute effects on respiratory symptoms, lung function, and physiological parameters. 1 However, there is a lack of evidence on the use of acclimatization for individuals with asthma. 1

Nutritional Interventions

Antioxidant supplementation could potentially be used, though there is limited data exploring this intervention. 1, 4

Clinical Integration Strategies

Healthcare providers should integrate air pollution into disease management approaches through three key roles: 1

1. Advocate for air pollution mitigation as a health measure at institutional and governmental levels
2. Provide patients with personal measures to reduce exposures and associated risk at the individual level
3. Use communication tools such as air quality indices to help patients adjust activities when air quality is poor

High-Risk Populations Requiring Special Attention

Individuals with exercise-induced bronchoconstriction (mainly endurance athletes) may be more sensitive to the effects of some pollutants when exercising. 1 Endurance athletes appear very susceptible even at low concentrations of O3, with a dose-response relationship where higher concentrations elicit more severe negative symptoms. 1

Timeline for Health Benefits

Reducing pollution at its source can have rapid and substantial health impact. 2 Within a few weeks of pollution reduction:

• Respiratory and irritation symptoms (shortness of breath, cough, phlegm, sore throat) disappear
• School absenteeism, clinic visits, and hospitalizations decrease significantly
• Premature births, cardiovascular illness and death, and all-cause mortality decrease significantly

Health improvements continue to be associated with pollution decreases even below international standards, emphasizing that there is no safe threshold. 2

Common Pitfalls to Avoid

• Do not assume indoor environments are safe: Indoor air quality requires active management through filtration and ventilation control 1
• Do not rely on surgical or cloth masks for PM protection: Only N95/KN95/FFP2 respirators with proper fit provide meaningful PM reduction 3
• Do not ignore pollution levels below national standards: Health impacts occur even at levels below current WHO guidelines and most national standards 1
• Do not recommend mask use without considering heat stress: Masks can cause dyspnea in high temperatures, particularly during physical activity 1