Question

factorise 14asquare +4bsquare-9asquareb

Answer 1

.Bad air quality" and "Air quality" redirect here. For the obsolete medical theory, see Bad air. For the measure of how polluted the air is, see Air quality index. For the properties of air, see Qualities of air.

Air pollution from a coking oven.
Air pollution occurs when harmful or excessive quantities of substances including gases, particles, and biological molecules are introduced into Earth's atmosphere. It may cause diseases, allergies and even death to humans; it may also cause harm to other living organisms such as animals and food crops, and may damage the natural or built environment. Both human activity and natural processes can generate air pollution.

Indoor air pollution and poor urban air quality are listed as two of the world's worst toxic pollution problems in the 2008 Blacksmith Institute World's Worst Polluted Places report.[1] According to the 2014 World Health Organization report, air pollution in 2012 caused the deaths of around 7 million people worldwide,[2] an estimate roughly echoed by one from the International Energy Agency.[3][4]

Pollutants
Exposure
Indoor air quality (IAQ)
Health effects
Agricultural effects
Economic effects
Historical disasters
Alternatives to pollution
Reduction efforts
Regulations
Hotspots
Cities
Governing urban air pollution
See also
References
Further reading
External links