Study on the Effects of Air Pollution for Respiratory Allergy: A Population-Based Study in Taiwan

Study on the Effects of Air Pollution for Respiratory Allergy: A Population-Based Study in Taiwan

1. Introduction

Respiratory allergy is a global health problem affecting 10 to 15% of the global population and its prevalence continues to increase. According to Taiwan Association of Asthma Education, around 30% to 50% of the population is troubled by respiratory allergy and the percentage has significantly over the years. A survey [1] conducted by Taiwan Association of Asthma Education in 1985 and 2007 shows that , the percentage of elementary school children having respiratory allergy has increased to near 700% in the period of 22 years( 7.84% in 1985, 49.39% in 2007), manifesting how the phenomenon has exacerbated over the year. Even though respiratory allergy is not a lethal disease; however, it is socially and economically costly for the society as a whole.

The commonly acknowledged factors that contribute to respiratory allergy are the following:

1. Hereditability - If one of the parents has respiratory allergy, the chance of children having the same allergy is 30%
2. Humidity - Humidity level determines the survival and population development of house mite, which is a commonly acknowledged allergen. Studies have shown that humidity over 50% increases the survival for dust mites.
3. Seasonality - Change of season and temperature has the propensity to increase the chances of allergy
4. Pollutants - Air pollutant and particulate air can trigger inflammation in the lung and heighten the immune system’s sensitivity to both allergens and infection

        Even though possible allergens are known, there are still many questions unanswered. For example, among all the possible factors, which one carries more weight? Also, among all the pollutants, which one is the major attributor? In our study, we wish to investigate how temperature, humidity, and seasonality have impact on the trend of respiratory allergy patients and identify how significant each pollutant is in contributing to respiratory allergy. Also, we look in to how different age group and geographic areas are affected by the above factors.

1. Material and Methods

Database

The data were released by the National Health Insurance Administration Ministry of Health Welfare (NHIA).  The National Health Insurance Program finances compulsory universal health care for 99% of all of residents of Taiwan [2]. The dataset contains demographic information, such as age and area. This database is randomly sampled by NHIA from one million subjects enrolled in the National Health Insurance program from 2009 to 2011 [3].

Study Population

Monthly counts of medicine prescription for respiratory allergy were extracted from the medical insurance file. We identifies 8218720 people who lived in municipalities with air quality monitoring station during the study period. These patients were further analyzed by seven age groups (<1, 1-6, 7-16, 17-36, 37-56, 57-66, >67), by 36 months (Jan/2009-Dec/2011), by seasons (spring as February, March and April; summer as May, June and July; autumn as August, September and October; winter as November, December and January), by areas ( Taipei, North, Middle, South, Kaohsiung and East)