Environmental factors influencing the prevalence of respiratory diseases and allergies among schoolchildren in Chiang Mai, Thailand

Impact of Air Pollution on Atopic Dermatitis: A Comprehensive Review

Air pollution is associated with multiple health problems worldwide, contributing to increased morbidity and mortality. Atopic dermatitis (AD) is a common allergic disease, and increasing evidence has revealed a role of air pollution in the development of atopic dermatitis. Air pollutants are derived from several sources, including harmful gases such as nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO), as well as particulate matter (PM) of various sizes, and bioaerosols. Possible mechanisms linking air pollution to atopic dermatitis include damage to the skin barrier through oxidative stress, increased water loss, physicochemical injury, and an effect on skin microflora. Furthermore, oxidative stress triggers immune dysregulation, leading to enhanced sensitization to allergens. There have been multiple studies focusing on the association between various types of air pollutants and atopic dermatitis. Since there are many confounders in the current research, such as climate, synergistic effects of mixed pollutants, and diversity of study population, it is not surprising that inconsistencies exist between different studies regarding AD and air pollution. Still, it is generally accepted that air pollution is a risk factor for AD. Future studies should focus on how air pollution leads to AD as well as effective intervention measures.

Geographische Unterschiede zwischen städtischem und ländlichem Raum beim Risiko für atopische Dermatitis: Systematischer Review und Meta-Analyse

Die atopische Dermatitis ist die häufigste chronisch‐entzündliche Hauterkrankung im Kindesalter. Einige Studien kamen zu dem Ergebnis, das Risiko für diese Erkrankung sei im städtischen Raum höher als im ländlichen. Wir haben die verfügbaren Studien systematisch untersucht und eine Meta‐Analyse durchgeführt, um Unterschiede im Risiko für atopische Dermatitis zwischen städtischem und ländlichem Raum zu erkennen. Die Suche in den Datenbanken Embase und MEDLINE wurde am 19. April 2021 durchgeführt. Einschlusskriterium war das Stichwort “Beobachtungsstudie”. Wir haben außerdem Subgruppenanalysen bezüglich Patientenalter, Publikationsjahr und Land durchgeführt. Insgesamt wurden bei der Datenbanksuche 2115 Studien aufgefunden, von denen letztlich 43 Studien mit insgesamt 1 728 855 Patienten in die Meta‐Analyse eingeschlossen wurden. Ein Wohnsitz im städtischen Raum war mit einem erhöhten Risiko für atopische Dermatitis assoziiert; die Odds Ratio war 1,56 (95 %‐Konfidenzintervall 1,43–1,71). Dieses signifikant erhöhte Risiko war nur bei Kindern zu beobachten (Odds Ratio 1,55, 95 %‐Konfidenzintervall 1,39–1,73), nicht jedoch bei Erwachsenen. Hier betrug die Odds Ratio 1,29 (95 %‐Konfidenzintervall 0,99–1,67). Das Risiko für atopische Dermatitis ist in den letzten Jahrzehnten angestiegen, wobei das Risiko in Entwicklungsländern mit einer Odds Ratio von 1,95 höher liegt als in Industrieländern (Odds Ratio 1,35). Unsere Studie bestätigt die Assoziation zwischen atopischer Dermatitis und dem Wohnsitz im städtischen gegenüber dem ländlichen Raum.

Geographic differences in atopic dermatitis risk between urban and rural area: A systematic review and meta-analysis

Atopic dermatitis is the most common chronic inflammatory skin disease affecting children. Some studies have reported a higher risk of atopic dermatitis in urban areas than in rural areas. We systematically reviewed and carried out a meta-analysis to investigate the differences in the development of atopic dermatitis between urban and rural areas. The search was performed on April 19, 2021, using Embase and MEDLINE databases. Eligible for inclusion were observational studies. Subgroup analyses were performed for age, publication year, and country. We identified 2,115 studies, and 43 studies with 1,728,855 subjects were finally included. Urban residency was associated with an increased risk of atopic dermatitis, with an odds ratio of 1.56 (95% confidence interval, 1.43-1.71). A significantly increased risk was observed only in children, with an odds ratio of 1.55 (95% confidence interval, 1.39-1.73), but not in adults, with an odds ratio of 1.29 (95% confidence interval, 0.99-1.67). The risk has increased in recent decades, with a higher risk in developing countries (odds ratio, 1.95) compared to developed countries (odds ratio, 1.35). Our study provides evidence of an association between atopic dermatitis and urban compared to rural living.

Associations between indoor environment in residential buildings in wet and dry seasons and health of students in upper northern Thailand

We performed a repeated questionnaire study on home environment and health (six medical symptoms) in 1159 junior high school students (age 12.8 ± 0.7 years) in upper northern Thailand in wet and dry seasons. Data on outdoor temperature, relative humidity (RH), and air pollution were collected from nearest monitoring station. Odds ratios (OR) were calculated by multi-level logistic regression. Most common symptoms were rhinitis (62.5%), headache (49.8%), throat (42.8%), and ocular symptoms (42.5%). Ocular symptoms were more common at lower RH and rhinitis more common in dry season. Water leakage (28.2%), indoor mold (7.1%), mold odor (4.1%), and windowpane condensation (13.6%) were associated with all six symptoms (ORs: 1.3-3.5). Other risk factors included cat keeping, environmental tobacco smoke (ETS), other odor than mold odor, gas cooking, and cooking with biomass fire. Biomass burning inside and outside the home for other reasons than cooking was associated with all six symptoms (ORs: 1.5-2.6). Associations between home environment exposure and rhinitis were stronger in wet season. In conclusion, dampness-related exposure, windowpane condensation, cat keeping, ETS, gas cooking, and biomass burning can impair adolescent health in upper northern Thailand. In subtropical areas, environmental health effects should be investigated in wet and dry seasons.

A systematic review and meta-analysis of risk factors associated with atopic dermatitis in Asia

Background

Atopic dermatitis (AD) is a chronic, inflammatory skin disorder characterised by intense itch and eczematous lesions. Rising prevalence of AD has been observed worldwide including in Asia. Understanding the risk factors associated with AD may explain its pathogenicity and identify new preventive strategies and treatments. However, AD-associated risk factors and comorbidities specific to Asia have not been systematically reviewed.

Methods

We performed a systematic review in accordance with the Preferred Reporting Item for Systematic Review and Meta-Analyses (PRISMA) guidelines and summarised epidemiological studies investigating personal, family, and environmental factors and comorbidities associated with AD in Asia. Significant factors were assessed if they can be altered through lifestyle practices and further classified into non-modifiable and modifiable factors. Meta-analysis using the random-effect model was also conducted to provide an overall estimate for several significant factors.

Results

We identified a total of 162 epidemiological studies conducted in Asia. Among non-modifiable factors, a family history of atopic diseases was the most reported, suggesting the involvement of genetics in AD pathogenesis. Among modifiable factors, the results of meta-analyses revealed maternal smoking as the strongest risk factor with a pooled odds ratio (OR) of 2.95 (95% CI, 2.43-3.60), followed by active smoking (pooled OR, 1.91, 95% CI, 1.41-2.59).

Conclusion

While a family history may aid clinicians in identifying high-risk individuals, literature has long suggested the importance of gene-environment interaction. This review identified several modifiable factors including medical treatments, indoor and outdoor environmental exposure, and personal and family lifestyle specific to Asia. Based on the meta-analyses performed, prevention strategies against AD may start from changing personal and family lifestyle choices, especially smoking habits.

Identification of airborne pollen allergens from two avenue trees of India

An attempt has been made to detect airborne pollen of Lagerstroemia speciosa (LS) and Spathodea campanulata (SC) - two common avenue trees of India as potential sources of aeroallergens and also to identify the major IgE-reactive components present in them. The airborne pollen concentration was assessed using a Burkard sampler. A detailed questionnaire on clinical data of 1490 patients was recorded based on hospital data. We assessed the allergenicity of pollen by in vivo and in vitro tests. The correlation among meteorological factors, pollen seasons and allergenic potency of patients was assessed by multiple regression analysis. The sensitivity of patients to pollen antigens was highly correlated with pollen seasons. In SDS-PAGE, 15 protein bands were detected from LS pollen, while 14 bands from SC. The IgE-specific immunoblotting with patients' sera allergic to LS displayed five major allergens, while four major allergens were detected from SC. This would be the first report from India to prove the allergenic potentiality of airborne pollen of these two common avenue trees of India.

Children's Environmental Health in Thailand: Past, Present, and Future

Background:

There is increasing evidence of a link between environmental pollution and preventable diseases in developing countries, including Thailand. Economic development has generated several types of pollution that can affect population health. While these environmental health effects can be observed throughout life, pregnant women and children represent particularly vulnerable and sensitive groups.

Methods:

The published epidemiological literature investigating environmental chemical exposure in Thai children was reviewed, highlighting those that investigated associations between exposure and subsequent health outcomes.

Results:

The majority of the Thai epidemiological studies on environmental health in children were cross-sectional in design, with some demonstrating associations between exposure and outcome. The three main types of chemical exposure in Thai children were pesticides, heavy metals, and air pollution, which resulted from agricultural activities in countryside areas, industrial zones (both registered and unregistered establishments), mining, and traffic in inner cities. Major health outcomes included detrimental effects on cognitive function and cancer risk. Pesticide exposure was focused on, but not limited to, agricultural areas. The success of the Thai environmental policy to introduce lead–free petrol can be demonstrated by the decline of mean blood lead levels in children, particularly in urban areas. However, unregistered lead-related factories and smelters act as hidden sources. In addition, there is increasing concern, but little acknowledgement, about the effects of chronic arsenic exposure related to mining. Lastly, air pollution remains a problem in both dense city populations due to traffic and in rural areas due to contamination of indoor air and house dust with heavy metals, endotoxins and other allergens.

Conclusions:

The increasing number of published articles demonstrates an improved awareness of children’s environmental health in Thailand. Chemical hazards, including the improper use of pesticides, environmental contamination with heavy metals (lead and arsenic), and air pollution in inner cities and indoor air, continue to be growing issues.

Role of bilastine in the management of allergic rhinitis and urticaria: an Asia-Pacific consensus statement

The prevalence of allergic diseases is increasing globally, most particularly in middle- to low-income countries. This article examines the burden of allergic rhinitis and chronic urticaria in the Asia-Pacific region, unmet clinical needs, and the potential role of bilastine in the management of these conditions. An International Advisory Group meeting was convened in association with the Asian Pacific Society of Respirology Annual Congress in November 2014, followed by a literature review, and consensus-based outcomes from the meeting and literature review are described. Regional estimates of the prevalence of allergic rhinitis range from 10% to 50%, while little is known regarding the burden of urticaria in the Asia-Pacific region. A survey of allergy patients in the region identified fast, complete, and long-lasting symptom relief as the medication attributes most important to patients. International treatment guidelines for allergic rhinitis and urticaria advocate the first-line use of second-generation, no-sedating H1-antihistamines, such as bilastine, over their first-generation counterparts and a range of these agents are available to Asia-Pacific patients. The newer agents possess many of the properties of an "ideal" antihistamine (once daily administration, rapid and complete symptom relief, limited potential for drug-drug interactions, minimal side effects). The burgeoning prevalence of allergic diseases in the Asia-Pacific region and the uncontrolled symptoms that these patients experience demand a new antihistamine that offers the highest number of positive features according to the international guidelines.

Acute effects of air pollution on peak expiratory flow rates and symptoms among asthmatic patients in Chiang Mai, Thailand

The open burnings and forest fires have been recognized as the major sources of severe air pollution in the upper north of Thailand; however, there have been no clear evidences to show the associations between the air pollution and health effects in the area. We assessed the effects of air pollutants on the peak expiratory flow rates (PEFR) and symptoms in asthmatics. A cohort of 121 asthmatics was followed daily, for 306 days, for their PEFR and asthma symptoms. The daily air pollutants, including particulate matter with aerodynamic diameter <2.5 μm, particulate matter with aerodynamic diameter <10 μm (PM(10)), carbon monoxide, ozone, nitrogen dioxide (NO(2)), and sulfur dioxide (SO(2)), and the meteorological parameters, including pressure, temperature, relative humidity, rain quantity, and sunshine duration, were monitored. The PEFRs were fitted with general linear mixed models. The asthma symptoms were analyzed with the generalized estimating equations. There were positive associations of NO(2) with morning PEFR, with a coefficient of 0.06 [95% confidence interval (CI), 0.00-0.12]; of SO(2) with evening PEFR [with a range of coefficients of 0.88-1.00 (95% CI, 0.31-1.54)] and daily average PEFR [with a coefficient of 0.47 (95% CI, 0.00-0.94)]; of PM(10) with evening PEFR, with a coefficient of 0.02 (95% CI, 0.00-0.04). There was also negative association of PM(10) with ΔPEFR, with a coefficient of -0.01 (95% CI, -0.01 to -0.00). No pollutants were related to asthma symptoms. More studies are needed, particularly at low dose in adult asthmatics, to validate our findings.