Outdoor Air Pollution, as defined by Clean Air Act:

• Sulfur dioxide is a corrosive gas that comes from the combustion of coal and oil as well as volcanic eruptions. SO2 is a respiratory irritant and can harm aquatic life as well.
• Nitrogen oxides result from vehicular combustion and can cause respiratory syndromes in humans while building up in the atmosphere as photochemical smog.
• Carbon monoxide can result from incomplete combustion or malfunctioning exhaust systems. It interferes with oxygen transport in the bloodstream and can even cause death at high exposures.
• Particulate matter is solid particles suspended in air as a result of construction or combustion that releases soil or soot into the air. It contributes to cardiovascular disease and smog buildup.
• Lead is a gasoline additive that impairs the central nervous system
• Ozone is a pollutant formed by the combination of water, sunlight and oxygen. It degrades plant surfaces and reduces lung function.

Indoor Air Pollution: Developing and Developed nations

• Between 2 billion and 3 billion people in developing countries use wood, manure, or coal indoors for cooking. With little ventilation, indoor pollution is responsible for more than 4 million deaths annually worldwide.
• In China, India, and Sub-Saharan Africa, 80-90% of households use wood, manure, or coal inside to cook. This results in concentrations of PM that's 200 times higher than safe exposure limits.
• In more developed countries, carbon monoxide, asbestos, VOCs (such as formaldehyde) and radon (from groundwater or foundation cracks) can harm human health as well.

The Clean Air Act (1970) and new innovations

The Clean Air Act was the first major legislation to really make an impact on American air quality. It mandated emission controls on 187 air pollutants and introduced standards for industrial plants and new automobiles. As a result, all automobiles after 1970 had to undergo strict emissions testing. The Montreal Protocol (1989) phased out production of almost all ozone depleting chemicals, healing the ozone layer. Today, the Environmental Protection Agency (EPA) is revising emission standards to reflects updates to data. In 2015, air quality standards regarding ground-level ozone were strengthened.

USA SO2 emissions has declined from 26 million tons in 1982 to 10.3 million metric tons in 2008.

Furthermore, new innovations help to save lives: the Biolite HomeStove, for example, is a new technology that ensures complete combustion when creating heat and weights only 2 pounds. Sold in Kenya and Uganda, this revolutionary device is affordable and effective at removing indoor air pollution. Another example is the electrostatic precipitator, which removes PM from the atmosphere.

Several issues facing air pollution:

• Increasing Number of Industrial Facilities: factories are still being built.   Authorities have to find better regulation techniques or more effective abatement mechanism that reduce the impact they have on the environment. However, nuclear, wind, and solar technologies are improving and have no carbon footprint.
• Little to No Mitigation Systems: Though technology exists to remove pollutants from the atmosphere, the mosts effective way to prevent further air pollution would be lower emissions.
• Accountability: Many companies fail to comply with environmentally-friendly practices because they know they can get away with it. Governing bodies need to step in and make sure that all parties that are not respecting the regulations set forth by the established organizations must be held accountable for their actions.

How you can help: though it may feel hopeless, practicing the following over long periods of time can actually make a difference; simple practices such as not idling your car, partaking in public transportation and limiting electric use.

There is Hope

"Regulations that are currently in place in North America will prevent 100,000 to 800,000 premature BC-related deaths per year by 2030. In East Asia, Southeast Asia and the Pacific, the number of lives saved could be as high as 1.1 million a year." (BC=carbon emissions)

The United States has seen an increase in renewable energy infrastructure over the post decade. While it's not economically sustainable yet, technologies are improving which is driving down the prices of clean energy. Renewable energy is expected to grow by 15% in 2020 alone - showing hope for the future.