Association of ambient air pollution and meteorological factors with primary care visits at night due to asthma attack

Abstract

Aim The association of outdoor air pollution and meteorological elements with primary care visits at night due to asthma attack was studied. Methods A case-crossover study was conducted in a primary care clinic in Himeji City, Japan. The subjects were 956 children aged 0-14 years who visited the clinic with an asthma attack between the hours of 9 p.m. and 6 a.m. Daily concentrations of particulate matter, ozone, nitrogen dioxide, and a number of meteorological elements were measured, and a conditional logistic regression model was used to estimate odds ratios (ORs) of primary care visits per unit increment of air pollutants or meteorological elements. The analyses took into consideration the effects of seasonality. Results Of the 956 children, 73 (7.6 %) were aged \2 years and 417 (43.6 %) were aged 2-5 years. No association between daily ozone levels and primary care visits due to asthma attack at night in the spring or summer was found. An inverse relation between suspended particulate matter and primary care visits due to asthma attack was detected in the winter. ORs in the summer per degree increment in daily mean temperature was 1.31 [95 % confidential interval (CI) 1.09-1.56], and ORs in the autumn per hourly increment in daily hours of sunshine was 0.94 (95 % CI 0.90-0.99). Conclusion The findings of our study fail to support any association between daily mean concentration of air pollutant and primary care visits at night. However, we did find evidence indicating that certain meteorological elements may be associated with primary care visits

Association between PM2.5 and primary care visits due to asthma attack in Japan: relation to Beijing’s air pollution episode in January 2013

“…However, we did find evidence that ozone may be associated with PCVs due to asthma attack. Our previous study (n = 174) also found no association between PM 2.5 and PCVs among children in the 2010/2011 or 2011/2012 winters in the same setting [2]. Our present sample size (n = 112) was smaller than that in our previous study, and insufficient statistical power might accordingly be a limitation.…”

“…In a Japanese study, Yamazaki et al [9] found an association between ozone and PCVs due to asthma attack in the summer but not during the winter. In contrast, Yamazaki et al [2] found no stable association between ozone and PCVs in another study. We could not explain the reason of the uncertainty of the association.…”

“…purpose of treating emergency cases between 9 p.m. and 6 a.m. on weekdays [2]. Himeji City is located in western Japan, within 100 km of central Osaka and facing the Setonaikai Sea.…”

The short-term association between asthma hospitalisations, ambient temperature, other meteorological factors and air pollutants in Hong Kong: a time-series study

“…The nature of associations reported from past studies of asthma morbidity and temperatures have not been consistent, likely due to differences in climate, study design and statistical methodology. Some studies have found positive associations between temperatures and asthma admissions,23 24 some have reported negative associations,2 5 7 8 16 19 25 26 while a few have reported significant associations with high and low temperatures 6 27. The seasonal differences in associations of RH with asthma hospitalisations observed in this study, negative association in the cold season and positive in the hot season, have not been commonly reported in previous studies.…”

“…Despite the fact that many previous studies have reported associations between high temperatures and asthma morbidity,6 23 24 27 the direct biological mechanisms by which high temperatures cause asthma exacerbations are still unclear. A recent study suggested that the pulmonary c-fibre sensory nerve plays an important role in asthma in hot temperatures 47.…”