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.