air

A Greek Army Apache helicopter takes part in an air show at Athens Paleo Faliro coastal suburb  on September 25 , 2014. The show was a pre-event for  Athens annual Flying Week  at the weekend at an airfield north of Athens.

Louisa Gouliamaki/AFP

A Greek Army Apache helicopter takes part in an air show at Athens Paleo Faliro coastal suburb on Thursday

Hot air balloons lift off during a mass ascent at the 36th International Balloon Fiesta at the Ashton Court Estate near Bristol, which is Europe's largest ballooning event.

Ben Birchall/PA

Hot air balloons lift off during a mass ascent at the 36th International Balloon Fiesta at the Ashton Court Estate near Bristol, which is Europe’s largest ballooning event which officially begins on Friday

Hong Kong sees very high air pollution levels

Alex Hofford/EPA

Tourists from mainland China take photos in front of a large outdoor banner showing what Hong Kong looks like on a clean air day, on Wednesday. Hong Kong’s air pollution index’ reached ‘very high’ in Central and Western District, Causeway Bay and Mongkok, with ‘very high’ levels of toxic ozone and nitrogen dioxide recorded at roadside monitoring stations

Boy watches Israeli Air Force CH-53 helicopters fly over the Med

Amir Cohen/Reuters

A boy watches Israeli Air Force CH-53 helicopters fly over the Mediterranean Sea on a Tel Aviv beach during an aerial show forming part of celebrations for Israel’s Independence Day on April 16 2013, marking the 65th anniversary of the creation of the state.