Air quality worsened slightly last month, with the pollution index passing the benchmark 100 level on two consecutive days, compared with once in June.

Pollution hit a high on July 4 and 5, according to Environmental Protection Department figures.

A reading of 111 was recorded on July 4 at the general station, and 105 was recorded at the Causeway Bay roadside station. The next day at the same roadside station it was 107. The lowest reading was on July 2, when the index registered 26 at the general station and 47 at the roadside.