Int. J. Environ. Res. Public Health 2010, 7 3463 found that aircraft but not road traffic noise elevates children’s blood pressure. Because we only had two readings to estimate resting blood pressure and there were some potential acute noise effects during the baseline assessments, the data on resting blood pressure and exposure to chronic noise at school are best interpreted as tentative. The results also did not provide evidence that children exposed to traffic noise at school have different blood pressure responses when they are exposed to acute noise versus non-noise stressors. Instead, children exposed to traffic noise at school appeared to have a generally suppressed blood pressure response to acute stressors relative to children not exposed to traffic noise at school. All analyses controlled for potential confounds, including sex, age, BMI, and problems due to noise and interruptions during testing. The reactivity findings indicate that children from the noisy school tended to have lower blood pressure during exposure to acute noise and non-noise stressors than their counterparts from a quieter school. SBP reactivity was significantly lower in the noisy school than the quiet school during noise and non-noise challenges, whereas DBP reactivity was significantly lower in the noisy school than the quiet school during the non-noise challenge. To our knowledge, only one other study to date has examined the relation between chronic noise exposure and blood pressure reactivity in children [22], and it found results consistent with the present findings. In that prior study, children in a noisy community near an airport had lower SBP reactivity in response to an acute noise stressor than did their counterparts in a quieter community. Also, the prior study found no relation between noise exposure and DBP reactivity during an acute noise stressor, which also parallels the present findings. As an extension to the prior study, we found that children in a noisy school also had lower SBP and DBP reactivity to a non-noise stressor relative to children attending a quiet school. Thus, there is emerging evidence that chronic noise exposure is linked to dysregulation of blood pressure responses during acute challenges. An insufficient blood pressure response to an acute stressor may reflect an underlying pathophysiological process (e.g., dysregulation of the sympathetic-adrenal-medullary response system) and could undermine effective behavioral responses to stressors that demand a rapid mobilization of energy [26]. The fact that children in the noisy school were less reactive to both acute noise and the psychosocial stressor, mental arithmetic, indicates that physiological desensitization or habituation to noise is an unlikely explanation for the pattern of results uncovered. Rather, the data suggest some general downward shift in stress response efficiency during acute demands. There are several limitations of this study that must be considered when interpreting these findings. First, because the data were derived from a quasi-experimental design, a number of alternative explanations cannot be ruled out, particularly those related to spurious factors that could be associated with exposure to chronic noise and blood pressure reactivity. For example, community noise tends to covary with other ambient stressors, such as crowding and pollution [26]. Thus it is possible that other factors could have influenced the observed blood pressure differences across schools. Another limitation is that we had insufficient resources for measuring children’s noise exposure outside of school. According to an Environment Status Report by the Pune Municipal Corporation [27], noise levels at most places in the city of Pune exceed recommended levels, ranging from 43 to 109 dB(A). Thus, it is possible that children in both the quiet and noisy school live in communities varying widely in ambient noise levels. This unexplained variance in home noise levels could have attenuated some of the observed relations between noise exposure and blood pressure. A final limitation is that we were