Air pollution and conjunctivitis: Why you shouldn't ignore the link

In the last few years, growing concern over air pollution at the global level has increased tremendously, and most cities worldwide, including in India, fight against poor air quality. While its effects on the lung and cardiovascular system are well studied, another critical area that definitely needs attention is its impact on the eyes, especially relating to conjunctivitis or pink eye.

Understanding Air Pollution

Air pollution is a harmful blend of particles and gases that float around in our environment, and among the most worrisome are tiny specks known as Particulate Matter (PM). Specifically, PM2.5 and PM10 pose serious threats to our health. PM2.5 particles are so small that they can travel deep into the lungs and even slip into the bloodstream, sparking inflammation and other respiratory issues. Nitrogen Dioxide (NO2), mostly from vehicle emissions, and Sulfur Dioxide (SO2), produced by industries, are also major offenders. These pollutants, combined with Volatile Organic Compounds (VOCs) from everyday products like paints and cleaning agents, contribute to deteriorating air quality, which has been linked to various health problems, including conjunctivitis.

Air Pollution and Conjunctivitis Risk

Conjunctivitis is an eye infection that leads to redness, swelling, and discharge, often caused by viral or bacterial infections. Allergic conjunctivitis, however, stems from reactions to environmental allergens like pollen and animal dander. Recent studies, including a significant one from 2014, have highlighted a concerning link between air pollution and the increased risk of developing allergic conjunctivitis. Exposure to fine particulate matter, especially PM10 and PM2.5, has been identified as a major factor in worsening symptoms. The study also found that elevated levels of Nitrogen Dioxide (NO2) were closely tied to higher cases of allergic conjunctivitis, including severe forms such as Atopic Keratoconjunctivitis (AKC) and Vernal Keratoconjunctivitis (VKC).

Impact of Specific Pollutants

Different pollutants impact eye health to varying extents, with some showing a stronger connection to conjunctivitis than others. Nitrogen Dioxide (NO2), a byproduct of combustion processes like vehicle emissions, has been directly linked to a higher risk of allergic conjunctivitis. A hospital-based study found that the prevalence of Atopic Keratoconjunctivitis (AKC) increased by 1.23 times for every quintile rise in NO2 exposure. Similarly, Vernal Keratoconjunctivitis (VKC), a severe form of the condition, was significantly associated with both nitrogen oxides (NOx) and PM10, with odds ratios of 1.72 and 1.54, respectively. Ozone (O3), another pollutant, has also been linked to an increase in outpatient visits for allergic conjunctivitis, especially during warmer months when sunlight boosts ozone levels.

Weather and Environmental Factors

In addition to pollutants, changes in weather patterns can exacerbate the symptoms of conjunctivitis. Research has shown that factors such as temperature and humidity influence the severity of allergic conjunctivitis. Increased temperatures, in particular, have been correlated with a rise in outpatient visits for conjunctivitis, as warmer weather often leads to higher levels of ozone and NO2. Interestingly, studies indicate that people under 40 years of age are more vulnerable to these environmental factors, especially when levels of NO2, O3, and temperature fluctuate. Older individuals, on the other hand, seem to be more affected by NO2 alone.

Protecting Your Eyes

Given the established link between air pollution and conjunctivitis, taking protective measures against environmental pollutants is essential. Sunglasses provide an effective shield against direct exposure to airborne particles, while staying indoors during high-pollution times—such as early mornings and late afternoons—can help reduce irritation risks. Using air purifiers at home lowers indoor pollution levels, especially in areas prone to outdoor pollution. For those already experiencing conjunctivitis symptoms, rinsing the eyes with cold water, cold fomentation or using ice packs in case of swelling can help. Avoid contact with the allergen to prevent further irritation and strictly avoid rubbing of eyes even when experiencing itching.

(Dr. Ajay Sharma, Founder and Chief Medical Director of Eye-Q Eye Hospitals)