Q&A: Air pollution, weather changes impact outpatient visits for allergic rhinitis
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When concentrations of air pollution increased and the weather changed, more people visited outpatient clinics for allergic rhinitis, according to a letter published in Allergy.
The study examined meteorological and pollutant data as well as 178,692 daily outpatient visits for allergic rhinitis in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in China from 2014 to 2019.
Particulate matter at 2.5 µm (PM2.5) and 10 µm (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2) and maximum 8-hour moving average ozone (O3_8h) all had strong effects on daily outpatient visits for allergic rhinitis. Windspeed, relative humidity and temperature had varying impacts on daily visits as well.
Healio spoke with Huanping Lu, PhD, of the Guangdong Ecological Meteorological Center, and Qintai Yang, MD, PhD, of the department of otolaryngology-head and neck surgery at Third Affiliated Hospital of Sun Yat-sen University, to find out more about the study.
Healio: What prompted this study?
Lu and Yang: Allergic rhinitis is a very common disease that affects the health of 10% to 40% of the population, and the prevalence of self-reported allergic rhinitis has been reported increasingly from 11.1% to 17.6% in China. Climate change and air pollution are thought to be responsible for the global increase in allergic diseases.
Furthermore, there have been considerable environmental changes in China over the past few decades. The investigation of air pollution and meteorological factors in the incidence of allergic rhinitis is important and will be a useful guide in China.
However, most studies here on air pollution and meteorological factors affecting allergic rhinitis have been conducted in single cities located at medium latitude. But the GBA is a low-latitude urban agglomeration and a rare oasis at a low latitude.
These factors prove that this study to investigate the associations between daily meteorological factors and air pollutants on allergic rhinitis in the GBA is particularly important.
Healio: Were there any particularly surprising or significant results?
Lu and Yang: We conducted a stratified analysis among 178,692 allergic rhinitis outpatients and found that increases in air pollutant concentrations and changes in meteorological conditions are associated with the number of outpatient visits for allergic rhinitis.
For air pollutants, we analyzed their lag effects and described the effect excess risk, which demonstrated that each 10 g/m3 increase in concentrations of SO2, NO2, PM2.5, PM10 and O3_8h was associated with significant increases in daily allergic rhinitis outpatient visits.
For meteorological factors, low temperature, low humidity and high wind speed might be associated with the number of outpatient visits for allergic rhinitis. The risk for daily allergic rhinitis visits was negatively correlated with temperature when the temperature was below 16.4°C. The exposure-response relationship curve of wind speed was nearly S-shaped. Also, the exposure-response relationship curve of relative humidity showed a steep slope in the whole range.
In analyses stratified by gender and age, both males and females were sensitive to air pollution and cold temperatures, but females were more sensitive to dry and extreme wind effects. Compared with children and older adults, adolescents and younger adults appeared more vulnerable to cold temperature and dry effects. Meanwhile, older adults were more sensitive to particulate matter (PM2.5 and PM10), whereas adolescents and younger adults were more susceptible to the adverse effects caused by SO2, NO2 and O3.
Healio: How can doctors use these findings to improve care?
Lu and Yang: We have confidence to say that our findings have important implications for policy and clinical practice. Air pollution is known to have adverse effects on population health, but most attention has been focused on the elderly and children, who usually have low immunity. But in this study, we found that adolescents and younger adults were also vulnerable to certain extreme meteorological factors. From the point of preventing disease and promoting health, they also need more attention from medical personnel.
In addition, population-based health promotion activities are essential to raise awareness of adverse environmental exposures and early-onset allergic diseases. It is necessary for doctors to strengthen popular science education for patients and their families to enhance people’s awareness of self-protection.
Healio: What is the next step in this research?
Lu and Yang: Given the lack of daily pollen and fungal spore monitoring in the GBA, we were not able to assess the impact of pollen concentrations on changes in outpatient numbers. We have recently established a joint force with scientists from the South China National Botanical Garden to carry out the pollen count in these regions. Hopefully, we will be able to provide pollen count in the GBA soon and include it in further research.
Furthermore, due to the uncertainties of the specific address of each outpatient, we only selected the nearest national basic meteorological station to the study hospital and the closest state-controlled air quality monitoring station to the meteorological station to ensure consistency and representation of the data.
In the future, we look forward to building a follow-up study of patients with allergic rhinitis, collecting information on the long-term residence of the research subjects and obtaining air pollution and meteorological data, but the details of the plan are still being discussed.
For more information:
Huanping Lu, PhD, can be reached at luhp@gd121.cn.
Qintai Yang, MD, PhD, can be reached at yangqint@mail.sysu.edu.cn.