Optometrists understand how a range of factors can impact vision and overall eye health. Often, patients come into our offices with dry eye complaints, and we point to factors such as age, dry air, increased digital device use, or systemic medications.
However, depending on where your practice is located, air pollution may be a cause of dry eye.
Air quality and vision
As someone who practices in the New York City area, I consider air quality as a significant risk factor when it comes to dry eye.
Over the course of a year, I am in contact with several patients who travel to areas with better air quality for days, weeks, or months at a time. Shortly after coming home, many of them report an increase in dry eye symptoms including burning, stinging, tearing, and fluctuations in vision.
On the opposite end, I see several patients who travel to places that are far more polluted than New York City, and they come home with those same symptoms—sometimes even worse.
Air pollution overview
Air pollution can be described as a complex mixture of pollutants, including particulate matter, chemical substances, and biological materials.1 Its adverse effects are difficult to avoid because, unlike the food we eat or the water we drink, people cannot choose what type of air to inhale.
The most recent “State of Air” report released by the American Lung Association indicates at least 125 million Americans live in counties with an unhealthy quality of air.2
The six common air pollutants acknowledged by the United States Environmental Protection Agency (EPA) include:
• Ground-level ozone
• Particulate matter
• Carbon monoxide
• Sulfur dioxide
• Nitrogen dioxide
Health risks accompany both chronic and acute exposure to air pollution, such as respiratory infections, cardiovascular problems, and pulmonary disease. People who assume the most risk from its dangers are infants, pregnant women, those who work outdoors (especially in cities), and the elderly.1
In addition, it can be supposed that the economic consequences of illnesses caused by air pollution are far reaching.
The main overall health problems typically associated with air pollution include:
• Asthma attacks
• Wheezing, coughing, and shortness of breath
• Cardiovascular disease
• Chronic obstructive pulmonary disease
• Lung cancer
• Premature death
Air pollution and the eyes
Several international studies have attempted to detail the impact of air pollution on the ocular surface.
One study suggests that high ozone levels and low humidity levels are associated with dry eye in the Korean population.3
Another study found evidence that outpatient visits for conjunctivitis increased significantly with higher levels of air pollution in Hangzhou, China.4
The results of these studies are interesting because not only is dry eye disease linked with air pollution but also with eye infections.
Additional research implies that particulate matter on the ocular surface is more harmful in dry eyes as compared to normal eyes, which indicates that dry eye patients may be more vulnerable in places where air quality is low.5
Furthermore, increased levels of nitrogen dioxide (NO2) in the air is associated with nosebleeds, dry cough, and eye irritation, which makes the case for a correlation between air pollution and dry eye disease even stronger.6
The main ocular health problems associated with air pollution stem from increased levels of dry eye, which includes the following symptoms:
• Burning or stinging
• Increased hyperemia
• Fluctuations in vision
• Foreign body sensation
• Contact lens intolerance
1. Mannucci PM, Harari S, Martinelli I, Franchini M. Effects of health on air pollution: a narrative review. Internal Emerg Med. 2015 Sept;10(6):657-62.
2. State of the Air 2017. American Lung Association. Available at: www.lung.org/assets/documents/healthy-air/state-of-the-air/state-of-the-.... Accessed 10/7/18.
3. Hwang SH, Choi YH, Paik HJ, Wee WR, Kim MK, Kim DH. Potential Importance of Ozone in the Association Between Outdoor Air Pollution and Dry Eye Disease in South Korea. JAMA Ophthalmol. 2016;134(5):503-510.
4. Fu Q, Mo Z, Lyu D, Zhang L, Qin Z, Tang Q, Yin H, Xu P, Wu L, Lou X, Chen Z, Yao K. Air pollution and outpatient visits for conjunctivitis: A case-crossover study in Hangzhou, China. Environ Pollut. 2017 Dec; 231(Pt 2): 1344-1350.
5. Han JY, Kang B, Eom Y, Kim HM, Song JS. Comparing the Effects of Particulate Matter on the Ocular Surfaces of Normal Eyes and a Dry Eye Rat Model. Cornea. 2017 May;36(5):605-610.
6. Wiwatanadate, P. Acute air pollution-related symptoms among residents in Chiang Mai, Thailand. J Environ Health. 2014 Jan-Feb;76(6):76-84.