Summary of comments and responses: addition of precursors to particulate matter, chapter 8

8. Ammonia

Comment received

Half of gaseous ammonia in the atmosphere is naturally occurring. Ammonia is essential to life, and can be beneficial in terms of controlling other pollutants. It is not like the other precursors and should be removed from the bundle.

Response

The Priority Substance List (PSL) Assessment for PM₁₀ and the PM SAD clearly identify that ammonia, along with the other precursors, participate in chemical reactions that result in the formation of PM₁₀, which is toxic.

The federal government recognizes the natural sources and unique risk management challenges posed by ammonia, however, it is clearly an important precursor to PM₁₀ in specific areas of the country. The Government is committed to working with stakeholders and its provincial and territorial partners to identify priorities for action and develop specific risk management tools to reduce emissions of PM₁₀ and the precursors.

Comment received

The significance of the role ammonia plays in PM formation is still unclear and no risk management strategies for ammonia have been identified. Until these issues are resolved, ammonia should not be listed on Schedule 1.

Response

The uncertainties do not refute the conclusion that the precursors, including ammonia, participate in chemical reactions that result in the formation of PM₁₀, which is toxic. Rather, these uncertainties will be considered, as mentioned in the previous response, during the risk management stage when identifying priorities for action and developing specific risk management tools to reduce emissions of PM₁₀ and the precursors.

Comment received

Basing the listing for gaseous ammonia on estimated emission rate statistics extrapolated from US or European data is inappropriate.

Response

The listing on Schedule 1 of CEPA 1999 was in no way based upon estimated emission rate statistics. The listing is based on sound science conducted over the past decade. Gaseous ammonia plays a significant role in the formation of ambient fine particulate matter.

Environment Canada is continuing to revise and improve the National Emissions Inventory of Atmospheric Ammonia to more accurately reflect the Canadian situation. EC is working towards incorporating more Canadian data and emission rates into the inventory for the largest source sectors.