Adverse air quality can kill many organisms including humans. Ozone pollution can cause respiratory disease , cardiovascular disease , throat inflammation, chest pain, and congestion . Water pollution causes approximately 14,000 deaths per day, mostly due to contamination of drinking water by untreated sewage in developing countries . An estimated 500 million Indians have no access to a proper toilet,   Over ten million people in India fell ill with waterborne illnesses in 2013, and 1,535 people died, most of them children.  Nearly 500 million Chinese lack access to safe drinking water.  A 2010 analysis estimated that million people died prematurely each year in China because of air pollution.  The WHO estimated in 2007 that air pollution causes half a million deaths per year in India.  Studies have estimated that the number of people killed annually in the United States could be over 50,000. 
As with many other environmental problems, water pollution is hard to tackle because its effects (which may be long-term and subtle) are often hard to trace to a particular cause. If we know an oil tanker has broken up near the coast, we can instantly identify that as a potential source of water pollution and take immediate action to reduce any effect it may have. But we can look at a dirty river, devoid of fish and other life, running through a city, and find it hard to know who or what to blame. And if we can't easily identify the cause of the problem, coming up with a solution can be almost impossible.