A bottom-up emissions inventory of prominent greenhouse gasses (carbon dioxide, methane, and nitrous oxide) and criteria air contaminants (carbon monoxide and oxides of nitrogen) in the Greater Toronto Hamilton Area (GTHA) was developed for the year 2016. Emissions from agriculture, buildings, ecosystems, industries, and transportation were estimated in layers and then summed in each individual grid square. The inventory used non-proprietary data and was distributed on a fine grid (four square kilometre grid cells). It was found that the Greater Toronto Hamilton Area produced 58.6 megatonnes of carbon dioxide equivalent, 194,460 tonnes of carbon monoxide, and 106,140 tonnes of nitrogen oxides. Traffic produced the most of all pollutants except methane, which was dominated by waste (landfills). The inventory was validated against published inventories from Environment and Climate Change Canada. The developed methodology can be used by other municipalities to assess their state of carbon neutrality and air pollution following the GTHA as an example.