Mondi said that its Merebank paper mill had cut "chemical oxygen demand," a key pollutant, in 2005, and that it was cutting its sulfur dioxide emissions. But by the company's own estimate, the mill still releases about three times the combined amount of sulfur dioxide produced by Mondi plants in five other nations, and the other plants operate at nearly six times the capacity. Merebank uses a coal-fired power plant, while the others burn cleaner fuel.

Just as the Gates Foundation investments in Mondi, BP and Royal Dutch Shell have been very profitable, so too have its holdings in the top 100 polluters in the United States, as rated by the University of Massachusetts, and the top 50 polluters in Canada, as rated by the trade publication Corporate Knights, using methods based on those developed by the university.

According to the foundation's 2005 figures, it held a $1.4-billion stake in 69 of those firms. They included blue chips, such as Chevron Corp. and Ford Motor Co., as well as lesser-known companies such as Lyondell Chemical Co. and Ameren Corp.

At the same time, the foundation held a $2.9-billion stake in firms ranked by the investment rating services as among the worst environmental stewards, including Dominion Resources Inc. and El Paso Corp.

Without double-counting companies flagged by both the University of Massachusetts and the rating services, the combination totals an investment of about $3.3 billion.

The Gates Foundation did not respond to written questions about its investments in companies that were high polluters or those rated as poor environmental stewards.

Drugs out of reach

NEARLY every morning, a 56-year-old retired soldier named Felix makes a short trek from his house on the outskirts of Lagos, Nigeria, to a factory to purchase a 40-cent block of ice.

Felix has a pressing, private reason to get the ice: He needs it to keep his medicine from melting.

Two years ago, Felix's wife died from AIDS, and he learned he was HIV-positive.

He told his six children, now 16 to 24 years old, but no one else. He was afraid of the stigma of HIV. He agreed to be interviewed only if he was identified by his first name alone. "I thought the world had come to an end for me," Felix said. "Everyone believes that once you have it, you're a living ghost."

He took antiretroviral drugs and felt better. But his treatment was interrupted frequently because he could not afford the cost: $62 a month. His pension as a former staff sergeant was $115 a month, and the money came sporadically.

Worse, his body soon stopped responding to the drugs. His kidneys began to fail, and his count of immune cells crucial to fight off infections plummeted.

In May, Felix began taking Kaletra, a second-line AIDS drug — needed when the first round of treatments fail.

His health rebounded, but it came at a cost.

Gel capsules of Kaletra melt in Nigeria's sweltering climate, where temperatures often top 100 degrees. Felix kept his Kaletra in a small chest filled with ice.

Each day, he had to go get more ice. And each day, he had to take Kaletra precisely at 10 a.m. and 10 p.m. These things made it difficult for him to work, even at odd jobs.

A new version of Kaletra does not require refrigeration. But his physician, Dr. T.M. Balogun, who helps run the AIDS program at Lagos State University Teaching Hospital, told him not to get his hopes up.

The hospital is helped by the Nigerian government, which gets money from the Global Fund to Fight AIDS, Tuberculosis and Malaria. The fund has been awarded $651 million by the Gates Foundation. Yet the hospital does not offer the new Kaletra. It is too expensive.

In August, private pharmacists said they could sell it for $246 a month. But that was far out of Felix's reach.