Air Pollution and Your Health: Are We Risking Our Lives for the Big City?

Caitlin Register, Mercer University College of Pharmacy

According to the Centers for Disease Control and Prevention (CDC), air pollution presents a negative effect on asthma, chronic obstructive pulmonary disease (COPD), heart disease, and stroke. [1] The United States National Ambient Air Quality Standards (NAAQS), as established by Environmental Protection Agency, recommends ozone concentrations below 70 parts per billion (ppb) and annual average particles with a mass median aerodynamic diameter of less than 2.5 μg (PM2.5) concentrations less than 12.0 μg/m3 for “sensitive” populations such as asthmatics, children, and the elderly. For public welfare protection, PM2.5 concentrations less than 15.0 μg/m3 are recommended. [2] According to the World Health Organization (WHO), outdoor air pollution is estimated worldwide to cause about 8% of lung cancer deaths, 5% of cardiopulmonary deaths, and 3% of deaths from respiratory infections. [3] It is suggested that negative impacts on respiratory and cardiovascular health can follow both short and long-term exposures to particulate matter air pollution, and long-term exposure may be linked to atherosclerosis and childhood respiratory disease. With regard to these factors and public health, increased mortality may be the ultimate effect of air pollution. [4]

Air Pollution and Mortality in the Medicare Population
Design Open cohort; N= 60,925,443
Objective To assess the health effects of long-term exposure to varying levels of air pollution
Study Groups Ozone concentration ≥50 ppb (n= 14,405,094); ozone concentration <50 ppb (n= 46,520,349); PM2.5 concentration ≥12 μg/m3 (n= 28,145,493); PM2.5 concentration <12 μg/m3 (n= 32,779,950)  
Methods Included were all Medicare beneficiaries ≥65 years old in the continental United States who were alive on January 1 of the year following their Medicare enrollment. Ambient levels of ozone and PM2.5 were estimated based on previously published prediction models and monitoring data from the Environmental Protection Agency Air Quality System. Daily PM2.5 and ozone concentrations were predicted for nationwide 1 km by 1 km grids. Ozone concentration refers to the average concentration during the warm season.
Duration 13 years
Primary Outcome Measure All-cause mortality
Baseline Characteristics
Ozone ≥50 ppb Ozone <50 ppb PM2.5 ≥12 μg/m3 PM2.5 <12 μg/m3
Average ozone concentration, ppb 52.8 44.4 48.0 45.3
Average PM2.5 concentration, μg/m3 10.9 11.0 13.3 9.6
Average population density, persons/km2 0.7 3.8 4.8 2.2
Male, % 44.3 43.8 43.1 44.7
Average age at study entry, years 69.7 70.2 70.1 70.0
Average body mass index (BMI), kg/m2 27.9 28.4 28.0 28.4
History of smoking, % 44.9 46.2 45.8 46.0
Results
Risk of Death Associated with an Increase of 10 μg/m3 in PM2.5 or an Increase of 10 ppb in Ozone Concentration
PM2.5, hazard ratio (95% CI) Ozone, hazard ratio (95% CI)
Two-pollutant analysis
  Main analysis 1.073 (1.071-1.075) 1.011 (1.010-1.012)
  Low-exposure analysis 1.136 (1.131-1.141) 1.010 (1.009-1.011)
  Nearest-monitor analysis* 1.061 (1.059-1.063) 1.001 (1.000-1.002)
Single-pollutant analysis 1.084 (1.081-1.086) 1.023 (1.022-1.024)

*Analysis based on data from nearest monitoring site

Adverse Events Common Adverse Events: N/A
Serious Adverse Events: N/A
Percentage that Discontinued due to Adverse Events: N/A
Study Author Conclusions Significant evidence of adverse effects was found related to exposure to PM2.5 and ozone concentrations below national standards.

 

Utilization of the United States Medicare population provided a reportedly large patient population for the completion of this study, and because all cause mortality was the primary outcome and specific patient information was limited, there was no differentiation between cause of death. Mortality was shown to increase with PM2.5 concentrations below 15.0 μg/m3, National Ambient Air Quality Standards for the general population. Analysis showed an increase in risk of death associated with an increase of 10 μg/m3 in PM2.5 and 10 ppb in ozone concentration, meaning patients in more populated cities are at a higher risk of mortality than those in rural areas. As discussed previously, air pollution can be associated with adverse effects in multiple disease states, and should be considered among patients choosing to reside in dense, industrialized locations.

 

References

[1] Air Quality Public Health Issues. Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/air/air_health.htm. Accessed July 14, 2017.

[2] NAAQS Table. United States Environmental Protection Agency. Available at: http://www.epa.gov/criteria-air-pollutants. Accessed July 17, 2017.

[3] WHO (2009). Global health risks: Mortality and burden of diseases attributable to selected
major risks. Geneva, World Health Organization. Available at: http://www.who.int/healthinfo. Accessed July 14, 2017.

[4] Kelly FJ, Fussell JC. Air pollution and public health: emerging hazards and improved understanding of risk. Environ Geochem Health. 2015;37(4):631-49.

[5] Di Q, Wang Y, Zanobetti A, et al. Air Pollution and Mortality in the Medicare Population. N Engl J Med. 2017;376(26):2513-2522.

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