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Asphalt is manufactured by mixing asphalt cement with aggregates such as stone, sand or gravel. Asphalt cement is a product of oil refining that is used as a binder to glue the aggregates together in order to produce asphalt.
Asphalt is used in driveways, parking lots, airport runways, racetracks, tennis courts, and other applications where a smooth, durable driving surface is required. Asphalt is also known as Hot Mix Asphalt (HMA), blacktop, tarmac, macadam, plant mix, or bituminous concrete.
Environmental Impact on Air Quality
Asphalt manufacturing releases the following substances:
Criteria Air Contaminants (CAC):
- Particulate Matter (Total -TPM, <10 microns - PM10, and <2.5 microns - PM2.5)
- Nitrogen Oxides (NOx)
- Sulphur Oxides (SOx)
- Carbon Monoxide (CO)
- Volatile Organic Compounds (VOC)
Toxic substances:
- Polycyclic Aromatic Hydrocarbons (PAH)
- Carbon Dioxide (CO2)
Since PAH emissions are associated with Volatile Organic Compounds (VOC), minimizing VOC emissions also reduces PAH, odour and smog-forming pollutants.
Sources and Types of Air Pollutants Released from Asphalt Manufacturing
| Source | Pollutant |
| Batch Mix - Dryer and Mixing Tower | TPM, PM10, PM2.5, CO, SO2, NOx, CO2, VOCs, PAHs |
| Drum Mix - Drum Mixer | TPM, PM10, PM2.5, CO, SO2, NOx, CO2, VOCs, PAHs |
| Asphalt Storage Tanks | VOCs, CO, PAHs |
| Silo Filling and Truck Load-Out | PM2.5, CO, VOCs, PAHs |
| Aggregate Handling | TPM, PM10, PM2.5 |
| Road Dust | TPM, PM10, PM2.5 |
Contribution of Emissions from the Hot-Mix Asphalt Sector to all Industry Sectors - (HMA Annual Production: 32 million tonnes/year)
| Pollutant | Total Industrial Emissions* (ktonnes/y) | Hot-Mix Asphalt Emissions** (ktonnes/y) | Hot-Mix Asphalt Contribution to Industrial Emissions (%) |
| PM | 621 | 14.0 | 2.2 |
| PM10 | 287 | 4.8 | 1.6 |
| PM2.5 | 172 | 0.9 | 0.5 |
| SOx | 1,950 | 0.5 | <0.1 |
| NOx | 620 | 0.9 | 0.1 |
| VOC | 940 | 0.4 | <0.1 |
| CO | 2,177 | 5.0 | 0.2 |
| CO2*** | 123,000 | 570 | 1.5 |
Notes:
*Except for CO2, emissions are from Environment Canada's Criteria Air Contaminants Inventory for 1995 (Residual Discharge Information System, 1999) which reflect “process” emissions
**Emissions are for year 2000 for the HMA Sector and include both process and fuel combustion emissions
***Emissions are for year 1997 from Canada's Greenhouse Gas Inventory and include both “process” and “fuel combustion” emissions
Source: Multi-pollutant Emission Reduction Analysis Foundation (MERAF) for the Hot- Mix Asphalt Sector (http://www.ccme.ca/assets/pdf/hot_mix_asphalt_final_meraf_e.pdf)
Canadian Context
There are approximately 520 asphalt plants located across Canada.
Source: Multi-pollutant Emission Reduction Analysis Foundation (MERAF) for the Hot-Mix Asphalt Sector (http://www.ccme.ca/assets/pdf/hot_mix_asphalt_final_meraf_e.pdf)
The asphalt industry in Canada is represented at the provincial level by regional road builder and heavy construction associations and at the national level by the Canadian Construction Association. The industry is also represented by hot-mix asphalt producer associations in Ontario (Ontario Hot-Mix Producers Association - OHMPA), Quebec (Bitume Québec) and British Columbia (B.C. Hot-Mix Producers Association).
In 2000, the hot-mix asphalt sector directly employed an estimated 5,000 people and produced about 32 million tonnes of asphalt concrete for road paving. The sector contributed $1.12 billion to the Canadian economy (about 0.15% to the national Gross Domestic Product).
Emission Management Practices and Regulations
Federal Government
- The Canadian Environmental Protection Act, 1999 (CEPA 1999)
- National Pollutant Release Inventory (NPRI)
- National Ambient Air Quality Objectives (NAAQOs)
- Management of Toxic Substances, Environment Canada
Canadian Council of Ministers of the Environment (CCME)
Provincial Governments
British Columbia:
Waste Management Act - Asphalt Plant Regulation
Alberta:
Environmental Protection and Enhancement Act - Code of Practice for Asphalt Plants
Saskatchewan:
Manitoba:
Ontario:
Air Pollution Regulation (Environmental Protection Act - Reg. 346)
Airborne Contaminant Discharge and Monitoring (Environmental Protection Act - Reg. 127)
Quebec:
Environment Quality Act Q-2, r.25 - Regulation respecting hot-mix asphalt plants
New Brunswick:
Nova Scotia:
Prince Edward Island:
Newfoundland & Labrador:
Environmental Protection Act - Air Pollution Control Regulations
Yukon Territory:
Northwest Territories:
Environmental Protection Act - Asphalt Paving Industry Emission Regulations (pdf)
Nunavut:
In addition to government regulatory actions, several asphalt associations have developed guidelines on practices to promote continuing environmental improvements through voluntary actions of its industry members.
History
Asphalt is one of the world's oldest building materials. The first recorded use of asphalt as a road building material was in Babylon around 625 B.C., Procession Street, which led from King Naboppolassar's palace to the north wall of the city, was paved with asphalt and burned brick.
Take Action
Air emissions released by the asphalt sector can be reduced by using Best Available Techniques (BAT).
