NAAQS stands for national ambient ______ ______ standards.

NAAQS stands for national ambient air quality standards. This term refers to the regulatory limits set by the Environmental Protection Agency (EPA) to ensure that the air in the atmosphere remains clean and safe for public health and the environment. These standards are established for several major air pollutants, such as particulate matter, ground-level ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide.

The focus on "air quality" rather than "air safety" or "air monitoring" underscores the primary intent of the NAAQS, which is to protect public health and the environment from the harmful effects of air pollution, rather than specifically addressing safety protocols or monitoring systems. Similarly, "atmospheric quality" is not the correct terminology in this context, as "ambient air quality" specifically refers to the air in the surrounding environment as it is experienced by the public.