Children's exposure to pollutants in the air, water, food and soil is a major contributor to increased morbidity and mortality, especially in low and middle income countries. The World Health Organization (WHO) estimates that approximately one third of the disease burden in developing countries is attributed to modifiable environmental factors.

About 3 billion people use solid fuels (biofuels or coal) for cooking and they breathe air that is heavily polluted from burning these fuels. Ninety percent of rural households in low-income countries and a total of two thirds of the households in developing countries use biomass fuels for cooking and/or heating. This creates levels of particulate and pollutant gas mixtures that are much higher than permitted under typical regulatory limits. Globally, 4.3 million deaths were attributable to household air pollution in 2012, almost all in low and middle income countries. Thirteen percent of these deaths (534,000) were among children under 5 years of age, and the deaths were primarily from lower respiratory illnesses. Behavioral interventions such as keeping children away from the stove during cooking, using dry wood, and cooking outdoors, whenever possible, can be recommended by health care workers.

Worldwide, more than a thousand million adults smoke. About 6 million people a year, almost 16,000 every day, are killed by tobacco. This is more than killed by any other agent. By 2025, tobacco will kill 10 million people a year, 70% of them in low and middle income countries. Around 700 million, or almost half of the world's children, breathe air polluted by secondhand smoke. Secondhand smoke contains more than 4000 different chemical compounds, many of which are poisons Secondhand smoke exposure is linked to upper and lower respiratory illness, including otitis media and asthma, sudden infant death syndrome (SIDS), and some cancers. There is no safe level of exposure to secondhand smoke. The World Health Organization has urged all countries to pass laws requiring all indoor public places to be 100% smoke-free. Pediatricians can take an active role in supporting and educating parents about smoke-free public policies.

Children with elevated lead levels in their blood have lower intelligence scores, more language difficulties, attention problems, and behavior disorders. These adverse effects on intellectual development of children are seen at blood-level concentrations below 10 g/dL. Blood lead concentrations well above this level are frequently reported in children from Africa and Asia.

Leaded petrol has been a major source of children's exposure to lead. Currently, all but 4 countries have eliminated lead from petrol. Children also may be exposed from the use of lead ore in eye cosmetics and from lead in ceramic dishes or paint. Lead paint has long been outlawed in developed countries, but no legislation prevents lead paint from being sold in many parts of Asia and India. Children may be exposed from backyard cottage industries (eg, battery recycling). Children also may be exposed from living or playing near areas where mining occurs. A mass lead intoxication in northern Nigeria during 2010 resulted in the deaths of more than 200 children whose parents were engaged in small-scale gold mining activities. Pediatricians can be an important voice for policies to reduce children's exposure to lead.

The provision of safe drinking water is just as important as safe air to breathe. Nearly1.1 billion people in the world are still without access to safe drinking water. Nearly 2.6 billion people, including half of all Asians, lack access to sanitary means of excreta disposal.

With proper sanitation, proper hygiene, and safe drinking water, diarrhea can be decreased 22% and deaths resulting from diarrhea can be decreased 65%. Because diarrhea accounts for 12% of the deaths of children younger than 5 years, improvements in water and sanitation are critical to the child health agenda.

A considerable proportion of the disease burden for four key vector-borne diseases, malaria, schistosomiasis, Japanese encephalitis, and dengue, falls on children under 5 years of age. Several of these diseases are related to construction and housing design. Malaria risk is great for people living in poorly constructed houses (eg, with thatched roofs) than for those living in houses with brick and plaster walls and tiled roofs. Malaria risk is also increased if housing is located near water where mosquitoes can breed.