I noticed something yesterday (Tuesday) that is quite different from the last several visits I made here, and from when I lived here four years ago. There are many, many more cyclists on the roads, and the cyclists no longer wear face masks to filter out the particulate in the air. London’s air is still by no means pristine, as my skin indicates after just four days here, but it’s quite a bit better than it used to be. Some of that improvement is due to fleet turnover, primarily in taxicabs but also a little in buses. Some of the improvement is also due to London’s efforts to control congestion and use a fee-based system to reduce congestion in central London. I have not kept up with the developments in the congestion fee program, but I have noticed an appreciable change in air quality here.