Air pollution and emergency department visits for conjunctivitis: A case-crossover study

Abstract

Objectives: The purpose of this study was to examine the associations between emergency department (ED) visits for conjunctivitis and ambient air pollution levels in urban regions across the province of Ontario, Canada. Material and Methods: Information from the National Ambulatory Care Reporting System was used to create time-series records, for the period of April 2004 to December 2011, on emergency department visits of patients suffering from conjunctivitis. A total of 77 439 emergency department visits for conjunctivitis were analyzed. A time-stratified case-crossover design was applied, completed with meta-analysis in order to pool inter-city results. Odds ratio (OR) for an emergency department visit was calculated in different population strata per one-unit increase (one interquartile range -IQR increase in a pollutant's daily level) while controlling for the impacts of temperature and relative humidity. Results: Statistically significant positive results were observed in the female population sample, for nitrogen dioxide (NO 2 ) exposure lagged 5-8 days, with the highest result for the 7-day lag (OR = 1.035, 95% CI: 1.018-1.052) and for fine particulate matter with a median aerodynamic diameter of less than 2.5 μm (PM 2.5 ), for lags 6 and 7 days, with the highest result for lag 7 (OR = 1.017, 95% CI: 1.003-1.031). In the male population sample, statistically significant positive results were observed for NO 2 at lag 5 days (OR = 1.024, 95% CI: 1.004-1.045) and for ozone (O 3 ), at lags 0-3 and 7 days, with the highest result for lag 0 (OR = 1.038, 95% CI: 1.012-1.056). Also for males, statistically significant results were observed in the case of PM 2.5 exposure lagged by 5 days (OR = 1.003, 95% CI: 1.000-1.038) and sulfur dioxide (SO 2 ) exposure lagged by 1 and 2 days (OR = 1.016, 95% CI: 1.000-1.031 and OR = 1.018, 95% CI: 1.002-1.033). Conclusions: The findings of this study suggest that there are associations between levels of air pollution and ED visits for conjunctivitis, with different temporal trends and strength of association by age, sex, and season. include blurred vision, sensitivity to light, pain, foreign body sensations, itching, burning, discharges, and inability to tolerate contact lenses [40]. The conjunctiva is continuously bathed in a tear film, which acts as both a lubricant for eye movement and a protective barrier to dilute and remove harmful environmental impurities. Higher levels of ambient air pollution have been correlated with adverse effects on the tear film, ocular mucosa, ocular surface, and eyelid margins [30,36,39,[48][49][50]. Several population studies have examined the associations between air pollution levels and ED visits for eye diseases [17,21,23,24]. To our knowledge, no multi-city studies have investigated this link for cities in North America. Filling this gap in the epidemiologic literature is important; multi-city studies are known to give more reliable results, less liable to biases in comparison to studies concerned with individual urban centers [51...

How air pollution affects the eyes — a review

“…The number of patients' visits was bigger in the winter due to conjunc-tivitis in all seven compared areas, which varied by climate and population density. A Canadian study [4] which included 77 439 people affected by conjunctivitis, also confirms previous insights. It was observed that substances such as NO 2 , SO 2 , O 3 , and PM 2.5 are responsible for an increased number of medical appointments in men.…”

“…Symptoms of this disease are itchiness, burning, lacrimation, reddening of the eyes and severe photophobia. People who live in areas with heavy air pollution experience these symptoms more often [3,4]. Conjunctivitis can have diversified course, from mild to that jeopardizing the function of the eye.…”

External eye symptoms in indoor environments

“…This is further corroborated by three recent studies. Increase in emergency department visits for conjunctivitis that is associated with ambient ozone, nitrogen dioxide, and PM 2.5 . It was found in a population‐based cross‐sectional study (16 824 participants) that (mean annually) higher outdoor ozone levels and lower RH levels were significantly associated with perceived DE symptoms and diagnosed DED, but not with PM 10 .…”

Black Smoke and Sulphur Dioxide in the Air as Risk Factors for Dry Eye Disease

“…Air pollution is a mixture of a large number of pollutants and sometimes it is very difficult to determine the individual impact of each of them on eyes [22,23]. There is substantial evidence that chronic exposure to ambient air pollution is associated with subclinical changes of the ocular surface and the tear film at people living in urban areas [24][25][26].…”