Metro Manila (CNN Philippines, April 20) — Messages of condolences poured in for the family of former Senator Heherson “Sonny” Alvarez as he succumbed after a battle with COVID-19. He was 80.

Alvarez and his wife, Cecile Guidote-Alvarez, founder of Philippine Educational Theater Association (PETA), both contracted the viral disease and were intubated because of it. Guidote-Alvarez was later extubated.

The former senator and Isabela representative underwent an experimental plasma therapy used to treat COVID-19 patients struggling to combat the infection, according to his daughter Xilca Alvarez-Protacio.

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“I’m deeply saddened by the death of one of the original environmentalist advocates of the Philippine Senate,” Senate Majority Leader Juan Miguel “Migz” Zubiri said. “The Senate has lost another pillar of its rich history.”

Senator Sherwin “Win” Gatchalian said that Alvarez’s contributions to the country will never be forgotten.

Ruling party Partido Demokratiko Pilipino – Lakas ng Bayan also mourned the passing of Alvarez.

Alvarez was a two-term senator who started serving in the upper chamber in 1987 after the ouster of the late strongman Ferdinand Marcos.

While in the Senate, he championed environmental laws, including the Solid Waste Management Act and the Clean Air Act. He also authored the law which created the Department of Energy.

Prior to serving as senator, Alvarez was among the youngest delegates to the 1971 Constitutional Convention, which produced a charter which he ultimately rejected for being “Marcos-dictated.”

Alvarez went on exile to the United States during the Marcos regime and founded the opposition group Ninoy Aquino Movement.

After the fall of Marcos, Alvarez served in the Cabinet of then-President Corazon Aquino as secretary of the Department of Agrarian Reform from 1986 to 1987.

From 2001 to 2002, he again served in the Cabinet as then-President Gloria Macapagal-Arroyo’s Environment Secretary.

He later served as presidential adviser on overseas Filipino communities in 2003, on agrarian reform from 2005 to 2007, and on global warming and climate change from 2009 to 2010.

He was also the chairman and chief executive officer of the Philippine Mining Development Corporation in 2008 and was a Climate Change commissioner from 2010 to 2011.

He is survived by his wife and their children, Hexilon and Xilca.