Association between chemical components of PM2.5 and children's primary care night-time visits due to asthma attacks: A case-crossover study.

BACKGROUND: Few papers have examined the association between the chemical components of PM2.5 and health effects. The existence of an association is now under discussion. METHODS: This case-crossover study aimed to examine the association between the chemical components of PM2.5 and night-time primary care visits (PCVs) due to asthma attacks. The subjects were 1251 children aged 0-14 years who received medical care for asthma at a municipal emergency clinic. We measured daily average concentrations of hydrogen ion, sulfate ion, nitrate ion and water-soluble organic compounds (WSOCs), which are components of PM2.5. We estimated the odds ratios (ORs) of PCVs per unit increment (inter quartile ranges) in each chemical component of PM2.5 for the subgroups of warmer months and colder months separately. RESULTS: No association was seen between PCVs and PM2.5 mass concentrations the day before the PCVs in either warmer or colder months. In the warmer months, an association was seen with the concentrations of WSOCs and hydrogen ion the day before the PCVs (OR = 1.33; 95% CI: 1.00-1.76, OR = 1.18; 95% CI: 1.02-1.36, respectively). Furthermore, a negative association was seen between sulfate ion and PCVs (OR = 0.85; 95%CI: 0.74-0.98). No associations were observed in the colder months. CONCLUSIONS: We observed a positive association between PCVs and certain concentrations of WSOCs and hydrogen ions in warmer months. In contrast, sulfate ion showed a negative association.

Exposure to air pollution and meteorological factors associated with children's primary care visits at night due to asthma attack: case-crossover design for 3-year pooled patients.

OBJECTIVE: We examined the association of outdoor air pollution and meteorological parameters with primary care visits (PCVs) at night due to asthma attack. SETTING: A case-crossover study was conducted in a primary care clinic in Himeji City, Japan. PARTICIPANTS: Participants were 1447 children aged 0-14 years who visited the clinic with an asthma attack from April 2010 until March 2013. EXPOSURE: Daily concentrations of air pollutants and meteorological parameters were measured. PRIMARY OUTCOME: PCVs at night due to asthma attack. A conditional logistic regression model was used to estimate ORs of PCVs per unit increment of air pollutants or meteorological parameters (the per-unit increments of particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5) and ozone were 10 µg/m(3) and 10 ppb, respectively). Analyses took into consideration the effects of seasonality. RESULTS: We noted an association between PCVs and daily ozone levels on the day before a PCV (OR=1.17; 95% CI 1.01 to 1.35; p=0.04), as well as between PCVs and 3-day mean ozone levels before a PCV (OR=1.29; 95% CI 1.00 to 1.46; p=0.04), from April until June. We also observed an association between PCVs and daily PM2.5 levels on the day before a PCV from December until March (OR=1.16; 95% CI 1.01 to 1.33; p=0.05). Meteorological parameters, such as hours of sunshine from September until November, atmospheric pressure from April until June, and temperature from April until August, were also found to be associated with PCVs. CONCLUSIONS: The findings in the present study supported an association between ozone and PCVs and suggest that certain meteorological items may be associated with PCVs.

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

AIM: In January 2013, extremely high concentrations of fine particles (PM2.5) were observed around Beijing, China. In Japan, the health effects of transboundary air pollution have been a matter of concern. We examined the association between the levels of outdoor PM2.5 and other air pollutants with primary care visits (PCVs) at night due to asthma attack in Himeji City, western Japan. METHODS: A case-crossover study was conducted in a primary care clinic in Himeji City, Japan, involving 112 subjects aged 0-80 years who visited the clinic due to an asthma attack between 9 p.m. and 6 a.m. during the period January-March, 2013. Daily concentrations of particulate matter, ozone, nitrogen dioxide, and some meteorological elements were measured, and a conditional logistic regression model was used to estimate the odds ratios (OR) of PCVs per unit increment in air pollutants or meteorological elements. RESULTS: Of the 112 subjects, 76 (68 %) were aged <15 years. We did not note any association between daily PM2.5 levels and PCVs due to asthma attack at night. A positive relation between ozone and PCVs due to asthma attack was detected. The OR per 10 ppb increment in daily mean ozone the day before the visit was 2.31 (95 % confidence interval 1.16-4.61). CONCLUSION: These findings do not support an association between daily mean concentration of PM2.5 and PCVs at night. However, we did find evidence suggesting that ozone is associated with PCVs.

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

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.

Risk factors for wheezing, eczema and rhinoconjunctivitis in the previous 12 months among six-year-old children in Himeji City, Japan: food allergy, older siblings, day-care attendance and parental allergy history.

BACKGROUND: The aim of this study was to clarify whether some environmental and genetic factors (food allergy, older siblings, early day-care attendance and parents' allergy history) are related to the development of allergic symptoms (wheezing in the previous 12 months [WP], eczema symptoms in the previous 12 months [EP], and rhinoconjunctivitis symptoms in the previous 12 months [RP]) in Japanese children. METHODS: Using the modified version of the International Study on Asthma and Allergies in Childhood (ISSAC) questionnaire, we studied the prevalence of WP, EP and RP among six-year-old children attending 72 primary schools throughout Himeji City, Japan, during the two years from 2005 to 2006. RESULTS: Food allergy and parents' history of allergy showed a significant relationship with the prevalence of WP, EP and RP. Day-care attendance in the first two years of life and presence of older siblings showed a significant inverse relationship with the prevalence of RP. However, neither day-care attendance nor presence of older siblings was related to the development of W and ER. CONCLUSIONS: Among Japanese children, food allergy and parents' history of allergy are risk factors for WP, ES or RS. However, early day-care attendance and presence of older siblings might be protective factors against RS. Infections in early life may affect the prevalence of rhinoconjunctivitis in six-year-old children.