Summary: Transportation, in particular road transportation is a major man-made source of air pollution. Air pollution can impact health and ultimately productivity. So how will the changing vehicle landscape impact that?
Why this is important: With motorised vehicular transportation, much of the focus has been on their global warming potential. A little closer to home, the impact of pollution, not just from the drive trains but also from other sources needs to be considered.
The big theme: The implications of air quality in general, and pollution in particular, have various significant investment and decision-making considerations. Decreasing pollution with the aim of decreasing human illness and suffering is (should be) a goal unto itself. In practice it is also important to consider how such initiatives (that more often than not increase costs and dig into profits), will be beneficial to business in the long run, whether it be through decreased healthcare costs, increased health and productivity of the workforce, and reputational gains for such decisions.
Air pollution is the presence or release of a harmful substance in the air. Air is comprised mostly of nitrogen (about 78%), oxygen (about 21%) and small amounts of other gases including carbon dioxide. Pollutants are things that shouldn't normally comprise air and can be a mixture of both solid particles and gases. The most common pollutants are:
PMx = Particulate matter of varying sizes. These are tiny pieces of solids or liquids in the air. the 'x' denotes the average diameter of the particle. PM2.5 particles are 2.5 microns wide or 1/400 of a millimetre. PM2.5 is more likely to get into and deposit on the surface of the deeper parts of the lung. They can cause breathing difficulties but also a causal link to lung cancer has been found. PM10 are bigger at 10 microns wide and more like typical dust, irritating eyes, nose and throat.
NOx = Nitrous oxides typically a catch-all for nitric oxide (chemical symbol NO) which is odourless and colourless and nitrogen dioxide (NO2) which has a sharp smell and is a reddish-brown colour. NO reacts with ozone in the air to form NO2. Low levels can cause irritation, coughing, shortness of breath and nausea with consistent exposure over a few days leading to fluid build-up in the lungs. Combustion in air (e.g. burning fuels) will produce NOx.
Ozone = Ozone is a gas whose molecules are made up of three oxygen atoms (O3), rather than the normal two that we find in oxygen gas (O2). The 'Ozone layer' in the upper atmosphere protects us by absorbing most of the Sun's UV radiation. However, when ozone forms at ground level it can trigger asthma and reduce lung function. O3 can form when sunlight interacts with pollutants such as NOx, carbon monoxide and volatile organic compounds.
VOC = These are gases emitted from products and processes that can be harmful themselves or can react with other gases to form pollutants (see Ozone above). Examples include benzene, formaldehyde and toluene and sources include some solvents (e.g. paint, varnish, paint stripper), fuels, pesticides and disinfectants. As well as causing respiratory problems, they can also cause cancer.
Carbon monoxide = This is a colourless and odourless gas produced when fossil fuels are burned incompletely. The chemical symbol is CO. The biggest source in air pollution is from Internal Combustion Engine (ICE) vehicles. Once in the bloodstream, CO can make it difficult for the body's cells to bind to oxygen and that lack of oxygen causes breathing difficulties, flu-like systems and can be fatal.
SO2 = Sulphur dioxide is a colourless gas, which is very soluble in water and corrosive. It is released during volcanic eruptions but its main man-made source is from burning fossil fuels. Toxic when inhaled.