People clean the street during a cleaning campaign in Sanaa, Yemen, on Jan. 1, 2020. A cleaning campaign was launched in Sanaa on Wednesday to greet the New Year. More than 200 civil society organizations participated in the campaign, which aimed to promote environmental awareness among citizens. (Photo by Mohammed Mohammed/Xinhua)

People clean the street during a cleaning campaign in Sanaa, Yemen, on Jan. 1, 2020. A cleaning campaign was launched in Sanaa on Wednesday to greet the New Year. More than 200 civil society organizations participated in the campaign, which aimed to promote environmental awareness among citizens. (Photo by Mohammed Mohammed/Xinhua)

People clean the street during a cleaning campaign in Sanaa, Yemen, on Jan. 1, 2020. A cleaning campaign was launched in Sanaa on Wednesday to greet the New Year. More than 200 civil society organizations participated in the campaign, which aimed to promote environmental awareness among citizens. (Photo by Mohammed Mohammed/Xinhua)

Children clean the street during a cleaning campaign in Sanaa, Yemen, on Jan. 1, 2020. A cleaning campaign was launched in Sanaa on Wednesday to greet the New Year. More than 200 civil society organizations participated in the campaign, which aimed to promote environmental awareness among citizens. (Photo by Mohammed Mohammed/Xinhua)

People clean the street during a cleaning campaign in Sanaa, Yemen, on Jan. 1, 2020. A cleaning campaign was launched in Sanaa on Wednesday to greet the New Year. More than 200 civil society organizations participated in the campaign, which aimed to promote environmental awareness among citizens. (Photo by Mohammed Mohammed/Xinhua)

People clean the street during a cleaning campaign in Sanaa, Yemen, on Jan. 1, 2020. A cleaning campaign was launched in Sanaa on Wednesday to greet the New Year. More than 200 civil society organizations participated in the campaign, which aimed to promote environmental awareness among citizens. (Photo by Mohammed Mohammed/Xinhua)