دانلود رایگان مقاله کیفیت هوا و نتایج آموزشی کودکان

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4.3. school readiness

I next turn to operationalizing model 2, which includes measures of lifetime exposure to pollen, fine airborne particulate matter, and ozone. Recall that variation in lifetime exposure comes entirely from differences in exposure within a site, and since the sample is a cohort entering kindergarten during the Fall of 2010, the variation is entirely due so variation in air quality during the first year of life. To see this, note that all children in the same area were exposed to the same ambient air in 2010. This is true for 2009, 2008, and so on. Only during the year when the cohort was 14 This measure is as reported by parents. born was there variation in levels of exposure, driven by the timing of birth. Since all models control for age (in months), variation is driven by patterns of air quality during 2004-2005, when this cohort was born. In Table 5, I present results for estimates of Model 2. The dependent variables are measures of reading and math skills at the start of kindergarten and the measures of lifetime exposure are standardized (normal) here, since the units of measure of pollen and APM2.5 and ozone are different and are summed over multiple periods. The impact of ambient air quality on school readiness is somewhat different from the patterns of air quality on withinstudent test performance, in Table 3. While changes in performance from assessment to assessment were smaller for students tested on days with high levels of particulate matter (pollen and APM2.5), there is limited evidence that pollen or APM2.5 at the start of kindergarten negatively affect performance. Reading scores are lower on days with relatively high pollen, but APM2.5 has no similar effect.