An Athenian relaxes on a bench in the southern coastal suburb of Faliron yesterday in an attempt to find respite from a heat wave that reached the city. The temperature in Athens is expected to reach around 40 Celsius again today but will probably drop by three or four degrees tomorrow, weather forecasters said.

Rising pollution levels in Athens forced authorities to warn the elderly and people with heart or respiration problems to avoid leaving their homes yesterday as a record third heat wave this summer hit the city.

The level of ground-level ozone in the air exceeded the warning level of 180 milligrams per cubic meter (mg/m3) at three of the 14 monitoring stations in Athens, in the districts of Nea Smyrni, Liossia and Lykovrisi. The highest reading yesterday was in Lykovrisi, where it reached 206 mg/m3. The emergency level is 240 mg/m3.

“The high concentration of pollution that we have seen over the last few days is mainly due to the weather,” Yiannis Ziomas, a chemical engineering professor at the National Technical University of Athens told Kathimerini.

The temperature reached 40 Celsius (104 Fahrenheit) in Athens yesterday, making it one of the hottest days of the summer. Meteorologists said yesterday that it was the first time that three heat waves had been recorded in a single summer.

“High temperatures, intense sunlight and the lack of wind are ideal conditions for the development of ozone,” said Ziomas.

Experts warned that another bout of hot weather in September, when most Athenians have returned from their vacations, could have serious consequences.

“Something needs to be done,” said Ziomas. “There is a huge problem with old cars; they account for only 30 percent of vehicles on the road but are responsible for about 60 percent of the pollution.”