Air Pollution and Its Impact on Health

Air pollution is a global and major public health problem. The Global Burden of Diseases, Injuries, and Risk factors Study reported that air pollution accounts for 6.7 million deaths globally in 2016. In a recent study, researchers have reported that exposure to air pollutants is associated with age-related macular degeneration (AMD) and retinal layer thickening. The study findings were published in the British Journal of Ophthalmology.

Exposure to air pollution is associated with respiratory disease, cardiovascular disease, neurologic diseases, and eye diseases, including glaucoma and AMD. The potential mechanisms of air pollution-induced health effects include oxidative stress, activation of inflammatory pathways, and increased coagulation. Understanding the impact of air pollution on the retinal structures may provide insights into age-related eye diseases. Therefore, Dr. Sharon Y L Chua and team conducted a study to examine the associations of air pollution with both self-reported age-related macular degeneration (AMD), and in vivo measures of retinal sublayer thicknesses.

It was a cross-sectional study of 115,954 UK Biobank participants aged 40–69 years. Ambient air pollution measures included particulate matter, nitrogen dioxide (NO₂) and nitrogen oxides (NO_x). Researchers used self-reported AMD to identify overt disease. They also used SD-OCT imaging derived photoreceptor sublayer thickness and retinal pigment epithelium (RPE) layer thickness as structural biomarkers of AMD for 52,602 participants. They further examined the associations of ambient air pollution with self-reported AMD and both photoreceptor sublayers and RPE layer thicknesses.

Key Findings of the Study

• After adjusting for covariates, the researchers found that the people who were exposed to higher fine ambient particulate matter with an aerodynamic diameter <2.5 µm (PM_2.5, per IQR increase) had a higher risk of:
  • Self-reported AMD (OR=1.08),
  • Thinner photoreceptor synaptic region (β=−0.16 µm),
  • Thicker photoreceptor inner segment layer (β=0.04 µm) and
  • Thinner RPE (β=−0.13 µm).
• They also found that higher levels of PM_2.5 absorbance and NO₂ were associated with thicker photoreceptor inner and outer segment layers, and a thinner RPE layer.
• They noted that higher levels of PM₁₀ (PM with an aerodynamic diameter <10 µm) was associated with thicker photoreceptor outer segment and thinner RPE, while higher exposure to NO_x was associated with thinner photoreceptor synaptic region.

The authors concluded, "Greater exposure to PM_2.5 was associated with self-reported AMD, while PM_2.5, PM_2.5 absorbance, PM₁₀, NO₂ and NO_x were all associated with differences in retinal layer thickness."

For further information: Read more