• The objectives of the study were as follows:

1. To investigate the association between short-term PM2.5 exposure and daily mortality in multiple Indian cities

2. To estimate the mortality attributable to PM 2.5 levels exceeding WHO guidelines for safe exposure(24 h ambient PM 2·5 standards of 15 μg/m3 not to be exceeded more than three to four times per year) and even exceeding India's own less stringent ambient air quality standards for 24 h ambient exposure (i.e., 60 μg/m3).

• For the study, data was collected from daily all-cause mortality records maintained by the death registries of ten municipal corporations in India. 

• These areas represent the five climate-zone classifications needed to perform time-series analysis.

• The following interpretations have been made:
  1. Short-term PM 2.5 exposure is associated with a high risk of death in India, even at levels below the Indian standard.
  2. Associations were stronger for locally generated pollutants, supporting a causal link through causal modeling methods compared to conventional time-series analysis.

• The study underscores the urgent need for improved air quality management in India by providing critical evidence that short-term exposure to locally generated PM 2.5 significantly increases daily mortality rates, even at levels below current national standards. 

• Thus, it highlights the profound impact of air pollution on public health.

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