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Table 1 Symptoms of wheeze in the past 12 months - summary of ecological analyses*.

From: Which population level environmental factors are associated with asthma, rhinoconjunctivitis and eczema? Review of the ecological analyses of ISAAC Phase One

Ecological Issue Specific Factor 13-14 Year Age Group 6-7 Year Age Group
   Written Questionnaire Video Questionnaire Written Questionnaire
   Direction of effect P Value Direction of effect P Value Direction of effect P value
Economic development GNP + 0.007 + 0.08 + 0.84
Diet Calories from cereals and rice % - 0.0005 - 0.07 - 0.021
  Protein from cereals and nuts % - 0.002 - 0.015 - 0.062
  Starch g/day - 0.008 - 0.01 - 0.036
  Vegetables g/d - 0.041 - 0.205 - 0.262
  Vegetable Vitamin A μ/d - 0.04 - 0.159 - 0.235
  Trans fatty acids + < 0.0001 + < 0.05   
Immunisation Local immunisation rates for DTP# - 0.047    - > 0.05
  Local immunisation rates for measles - > 0.05    - > 0.05
TB exposure TB notification rates - 0.344 - 0.018   
  Estimated TB incidence rates - 0.262 - 0.263 - < 0.0001
Outdoor climate Altitude - > 0.05 + > 0.05 - > 0.05
  Annual variation in mean temperature - > 0.05 - > 0.05 - > 0.05
  Lowest monthly mean temperature + > 0.05 0 > 0.05 + > 0.05
  Annual variation in mean relative humidity - > 0.05 + > 0.05 - > 0.05
  Lowest monthly mean relative humidity 0 > 0.05 - > 0.05 0 < 0.05
  Mean relative humidity of ≥ 1 month < 50%humidity + > 0.05 + > 0.05 + > 0.05
Indoor climate Mean annual relative humidity 0 > 0.05 - > 0.05 - > 0.05
  Lowest monthly mean relative humidity + > 0.05 0 > 0.05 0 > 0.05
Tobacco smoking Tobacco consumption, ≥ 15 yrs 0 0.92 + 0.53 + 0.46
  Tobacco smoking, women + 0.06 + 0.72 + 0.32
  Tobacco smoking, men - 0.001 - 0.004 - 0.06
Pollen Total grass pollen count - 0.67     
  Days with high pollen counts - 0.39     
Antibiotic usage Antibiotic sales per capita - 0.21 + 0.01   
Air pollution PM10 - 0.03    - 0.06
Paracetamol Per capita paracetamol sales + < 0.0005    + 0.001
  1. *standardized for GNP. Where p values are recorded as > 0.05 the non significant p values were not provided in the source publication. #DTP = Diphtheria and tetanus toxoids and pertussis.
  2. Blank space = data not collected. + = positive association. - = inverse association. 0 = no association.