The need to control air pollution was already recognized in the first cities. In the Mediterranean at the time of Christ, laws were developed to place objectionable sources of odor and smoke upwind or outside the city walls. The adoption of fossil fuels in the 13th century in England focused especially on the effect of coal smoke on health, with several attempts at regulation regarding the type of fuel, the height of the chimneys and the time of use. Given the complexity of the air pollution problem, it is not surprising that these early attempts to control air pollutants have had limited success.
The 19th century was characterized by a growing interest in urban public health. This unfolded in a context of continuing industrialization, which saw smoke reduction clauses incorporated into the growing body of sanitary legislation in Europe and North America. However, a lack of both technology and political will doomed these early efforts to failure, except in the most blatantly destructive situations (for example, industrial settings such as those found around the Alkali Works in England).
Potentially, air pollutants can be found in the air anywhere, outdoors and indoors. Every day the vigilance of the competent bodies on the situation of the atmosphere in urban centers is increasing, where traffic and heating boilers are the main responsible for the overload of pollutants (CO, SO2, NOx, etc.) and poses a risk to the health of citizens.
Air pollutants can be divided into three groups:
- Air quality pollutants
- Atmospheric toxics
- Biological contaminants
Criteria for air quality pollutants
These are air pollutants that have been regulated and are used as indicators of air quality. Regulations or standards are based on criteria related to health and / or environmental effects. A key characteristic of these air pollutants is that they are generally widely distributed in the environment.
- Carbon monoxide
- Nitrogen dioxide
- Sulfur dioxide
Air toxics are sometimes referred to as "hazardous air pollutants." The Living Cities-Air Toxics program defines atmospheric toxics as' gaseous pollutants, in the form of aerosols or particles that are present in the air in low concentrations with characteristics such as toxicity or persistence to be a danger to human, plant or animal life '.
Sources of air toxics include emissions from motor vehicles, combustion of solid fuels, industrial emissions, and materials such as paints and adhesives in new buildings.
Atmospheric toxins have the potential to cause serious damage to human health and / or the environment. There are 5 priority air toxics:
- Polyaromatic hydrocarbons
'Biological contaminants' are another class of contaminants. They arise from sources such as microbiological contamination, for example molds, animal and human skin and food scraps. Biological contaminants can be airborne and can have a significant impact especially on indoor air quality.