Even as the world's political attention is focused on global warming, air pollution remains widespread and dangerous. It poses a daily threat to people, animals and plants, and leaves a brown-black haze that affects visibility. This is the right time for our government to lay the groundwork to ensure its climate change and air pollution policies dovetail. It is already consulting the public on tightening air quality standards, and another study under way seeks views on what the city can do to fight climate change.
The public clearly supports reducing air pollution and improving public health. The climate change study needs to discuss two aspects of air pollution with large climate-heating effects - black carbon and ozone. Reducing them is relatively easy, cheap and politically feasible compared with mitigating carbon emissions.
Black carbon is a form of particulate pollution that turns things brown-black. It results from inefficient and incomplete fossil-fuel burning, such as from poorly maintained vehicle engines and heavy bunker fuel for ships. Power plants and factories that burn coal inefficiently also contribute to the problem.
Black carbon's warming effect is equal to between 20 per cent and 50 per cent of the effect of carbon dioxide, making it the second or third largest contributor to global warming. Ozone, a natural occurrence in the upper atmosphere, filters ultraviolet radiation, and its depletion can have serious effects on humans, such as dramatically higher rates of skin cancer.
However, ozone can also occur at lower levels. It is formed when gases such as carbon monoxide and nitrogen oxide - which are derived from burning fossil fuels - react with sunlight. It is a heat-trapping greenhouse gas whose warming effect is equal to about 20 per cent of the effect of carbon dioxide, and is bad for our health.
The major sources of these emissions locally are vehicles, ships and power plants. While carbon stays in the atmosphere for centuries, black carbon and ozone remain for only a matter of days or weeks. Nonetheless, they are both widespread and being emitted continuously. Reducing them would see rapid improvements to air quality and global warming.
