Air
Humans can live only minutes without oxygen and therefore air quality is a fundamental determinant of the state of the human environment. The thin layer of atmosphere that supports and protects life on Earth is burdened by the waste products of energy consumption, industrial processes, biological processes, and geological events. Emissions of sulphur and nitrogen oxides, carbon dioxide, volatile organic compounds, ozone, heavy metals, hydrocarbons, and sulphate laden dust will compromise air quality. Chemical pollutants and airborne particles pose a direct health threat to young children who may suffer from irreversible cell damage, increased susceptibility to respiratory diseases, stunted lung growth, and chronic lung disease. The large number of children and the rapid rate of urbanisation in the developing world put ever greater numbers of people at risk. Mexico City, for example, has reputedly the worst air quality in the world with the potential to impact nearly 20 million people.
Carbon dioxide (CO₂) is released when wood, coal, oil or gas are burned and directly contributes to global warming and climate change. Since 1700, CO₂ concentrations have increased from about 280 parts per million (ppm) to 360ppm in 1995. This increase is due to the greater use of fossil fuels since the beginning of the industrial revolution. In 1992, global emissions of CO₂ totalled 26.4 billion metric tons (22.3 billion metric tons of industrial emissions), close to three times the 8.9 billion tons climate experts consider consistent with a stable atmosphere. The United States – by virtue of its high per capita level of emissions and large population – was responsible for some 22% of global industrial emissions that year, some 5 billion metric tons of CO₂. Climate experts worry that continued increases in atmospheric concentrations of CO₂ – already 28% higher than pre-industrial levels – could result in sufficient temperature increases to raise sea levels around the world and seriously disrupt agricultural production.
Other greenhouse gases include chloroflorocarbons (CFCs) used in refrigeration, nitrous oxides from combustion, and methane gas, all of which contribute disproportionately to global warming and ozone depletion. Energy intensive industrialisation in countries such as China and India, with no change in technology, will greatly increase the output of carbon. The United States emitted 1371 million tons of carbon into the atmosphere in 1993 up to 4.4% over 1990. China emitted 935 million tons with an increase of 13.5% and India produced 222 million tons and grew 23.5% over the same period. Continued economic growth in these populous countries will invariably contribute dramatically to the release of carbon. China may become the largest single source of atmospheric carbon in the world within 20 years. We cannot stop economic development but we can work to reduce per capita energy consumption: use new sources of renewable energy, and seek to reduce human fertility.
Climate change affects the environment on a global scale and also intensifies specific weather events. Weather disasters have become much more serious since 1989 and some of the events are truly catastrophic. Weather disasters will become more severe as global climate change continues, and the cost in lives and dollars of damage inflicted will increase.
While these kinds of global statistics are important to a broad understanding of the condition of the Earth’s environment, most people are far more sensitive to their local environment. City dwellers may measure air quality by its colour, breathability or by the incidence of respiratory disorders in their children. In rural areas, the need for cooking fuel may require a full day of wood gathering, instead of hours, or compel the substitution of dung (that would otherwise be used as fertiliser) for fuelwood.
Source: Adapted from: Environment for People: Building Bridges for Sustainable Development, UNEP, New York, 1997, pp. 4-9.
