In a 1994 assesment of environmental health risks prepared for the US Agency for International Development (USAID), American and Egyptian experts identified three leading environmental health risks for residents of Cairo: particulate matter air pollution, lead and microbiological diseases from environmental causes. The report also identified a number of less serious threats to human health, grouping them as middle, middle/lower, lower and uncertain risks. Ozone air pollution was one of two health risks in the “middle” category. The material presented below is drawn almost exclusively from this report.
Air pollution The concentrations of all major air pollutants in Cairo “approach or exceed levels that threaten public health.” 
Particulate Matter As a leading air pollutant, concentrations of particulate matter in Cairo’s air exceed health-based standards between five- and tenfold and are higher than in any other of the world’s largest cities. While industry is probably the leading source of particulate matter, other sources include natural sand and dust the open burning of trash and motor vehicles. Given Cairo’s desert setting, it would be near impossible to eliminate all particulate matter from the air, but eliminating all non-natural pollutants would avoid 3,000-16,000 deaths and 90-270 million person days of restricted activity per year.
Lead The report to USAID identifies lead as a leading contaminant in “all media,” meaning air, water and food. While lead emitted into the air by automobiles and lead smelters is the primary source of this pollutant, lead also finds its way into water, soil and food. While concentrations of lead in Cairo’s air exceed health standards in some parts of the city, it is the concentrations of lead in the blood of Cairo’s residents — resulting from exposure to all media — that is cause for alarm. Blood lead levels for men in Cairo averaged about 30 ug/dl in the 1980s, somewhat less for women and about 22 ug/dl for children. But for those Cairenes living near smelters, blood lead levels average more than 50 ug/dl and workers in these smelters averaged 80 ug/dl. The 30 ug/dl average for Cairenes overall is between six and seven times the levels for adults and children in the United States. The health consequences of these levels of lead in the blood include the loss of 4.25 IQ points per child; higher infant mortality due to the high levels of lead in their mothers’ blood; and between 6,000 and 11,000 premature deaths each year. According to the report to USAID, “The lead content of playground dust in Cairo often exceeds the US standard for remediation of contaminated soils at abandoned hazardous waste sites.” 
Ozone At high concentrations, ozone irritates the lungs and impairs lung function, causing symptoms such as coughing and chest discomfort among healthy individuals when exercising heavily. Asthmatics may begin to experience such symptoms at much lower levels of concentration. The report to USAID estimates that “most of Cairo’s population experience one to several days per year of mild adverse symptoms caused by ozone.”
Microbiological Disease Diarrheal diseases, infectious hepatitis and typhoid fever are among the microbiological diseases common to Cairo, responsible for one out of ten deaths among the population overall and as many as three out of ten deaths among young children. While non-environmental factors such as malnutrition and poor domestic hygiene play an important role in the incidence of these diseases, environmental factors also have an impact. Two environmental interventions — ensuring sufficient quantities of water in homes to support washing and other sanitary practices, and providing toilets and adequate sewerage in all residences — would have a significant impact on the incidence of infectious and parasitic diseases.
Water Pollution The Nile is quite clean as it enters Cairo. But downstream is a different matter as Cairo “exports” its residential and industrial wastewater to the north. Cairo’s drinking water is regarded as being quite safe at its source, as it is heavily treated. As it works its way through the city’s pipes and from the tap to the table, however, Cairo’s water may pick up numerous contaminants.
Waste Disposal Municipal garbage collectors and the zabbalin (traditional garbage collectors) together collect about two thirds of the solid waste generated by Cairenes. The remaining one third, however, remains in the streets — mostly in poor neighborhoods. This is similar to many developing country cities in which between one fifth and one half of solid wastes are not collected. Uncollected trash poses some threat to health, since it attracts rodents, insects and other animals that may transmit infectious diseases. Solid wastes may pose much more of a threat to the health of the garbage collectors themselves. A small proportion of solid wastes, hospital and other hazardous wastes do make their way to the zabbalin community where, for example, children can be seen disassembling used syringes.
Sources UN Population Division, Population Growth and Policies in Mega-Cities: Cairo (New York, 1990); US Agency for International Development/Egypt, Comparing Environmental Health Risks in Cairo, Egypt, Volume One, (Washington, 1994); World Resources Institute et al, World Resources, 1996-1997 (New York: Oxford University Press, 1996)