MANILA — President Rodrigo Duterte made a "joke" when he urged the public to reuse and disinfect their anti-virus masks and hands with gasoline, his spokesperson said Thursday.

"Kayo naman, 4 na taon na si Presidente, parang di n'yo pa kilala si Presidente. Joke only. Bakit naman tayo maghuhugas ng gasolina?" Presidential Spokesman Harry Roque said in a press briefing.

(The President has been in power for 4 years, it's as if you don't know him yet. That was a joke only. Why will we wash our masks with gasoline?)

The health department also said Wednesday that Duterte might not have been serious with his mask disinfection advice.

• Tip ni Duterte na 'gasoline disinfection' para sa face mask posibleng joke: DOH

The President said the public could dip their face mask in gasoline if they couldn't afford to use a disinfectant spray.

"Yung wala, ibabad mo sa gasolina o diesel... Totoo, if you want disinfection, maghanap ka ng gasolina. Babad mo 'yung kamay mo. Layo mo lang, huwag sa loob ng bahay n'yo," he said in a taped address aired Tuesday morning.

The US national public health institute warned of the risks posed by the flammable liquid when inhaled and exposed to skin.

Gasoline may cause asphyxiation in enclosed, poorly ventilated or low-lying areas, the Centers for Disease Control and Prevention (CDC) said in an advisory.

The CDC also said repeated or prolonged skin contact with liquid gasoline could degrease the skin, cause irritation and dermatitis.

First- and second-degree skin burns can occur from continuous contact with liquid gasoline for several hours, it added.

Exposure to gasoline through eye contact can also result in transient corneal injury, the CDC warned.

Gasoline is not part of the US Environmental Protection Agency's list of disinfectants for use against SARS-CoV-2, the virus that causes COVID-19.

Among those that have shown efficacy against the virus are ethyl and isopropyl alcohol, hydrogen peroxide and chlorine dioxide, the EPA said on its website.