Here's a summary of the colors of the gas emissions about: NOx (primarily nitrogen dioxide) is reddish-brown, SOx (primarily sulfur dioxide) is colorless, ammonia (NH3) is colorless, and carbon monoxide (CO) is colorless.

 Here's a summary of the colors of the gas emissions about: NOx (primarily nitrogen dioxide) is reddish-brown, SOx (primarily sulfur dioxide) is colorless, ammonia (NH3) is colorless, and carbon monoxide (CO) is colorless. 

Here's a more detailed explanation:

NOx (Nitrogen Oxides):

NOx is a group of gases, including nitric oxide (NO) and nitrogen dioxide (NO2). 

Nitric oxide (NO) is colorless and odorless . 

Nitrogen dioxide (NO2) is a reddish-brown gas with a pungent odor . 

NOx is a major component of smog and contributes to acid rain. 

SOx (Sulfur Oxides):

SOx refers to the oxides of sulfur, with sulfur dioxide (SO2) being the most common. 

Sulfur dioxide (SO2) is a colorless gas with a pungent odor . 

SOx is a precursor to acid rain and atmospheric particulate matter. 

Ammonia (NH3):

Ammonia is a colorless gas with a characteristic pungent odor . 

It is a precursor to particulate matter formation. 

Carbon Monoxide (CO):

Carbon monoxide is a colorless and odorless gas . 

It is produced by incomplete combustion and is a toxic air pollutant.