My Lords, I am delighted to support the idea that we should go for 20 miles per hour speed limits. The consequences of accidents at 20 miles per hour are much reduced. It makes for a much friendlier environment for walking and cycling and, as the noble Baroness said, it absolutely results in improvements in air quality. We do not need the centres of our towns and cities to be places of rush and danger, particularly with the decline in the viability of our high streets. We want them to be places where people feel comfortable, enjoy being and want to go to for all sorts of reasons. It ought to be easy and conventional. It ought to be the rule that, where people are numerous and we want them to be at ease, we go for a 20 miles per hour speed limit. It is absolutely justified in terms of the objectives of this Bill.
So far as air quality generally is concerned, I come back to the point, which I made in earlier debates, that we must have better research. We are quite capable of it. It is not very helpful to talk about PM2.5 as if this is some universal characteristic; it is just a size. It does not tell you anything about where the particles came from and what, therefore, can be done to reduce their concentration. As the noble Lord, Lord Tope, pointed out, in some places lockdown resulted in sharp drops in nitrogen oxides and other such pollutants but no
drop in PM2.5, so what is going on here? Were the particulates really coming from diesel engines, or have we, again, been barking up the wrong tree? It is not difficult to find the answer. All you have to do is pick out individual particles, analyse them and find out what their origins are. A particle that comes from burning wood is very different from a particle that comes from diesel—at least on average. A particle from emissions from a heavy industrial source is very different from one from a light engine. We need to do this research, and we need to do it locally, so that we can undertake actions that make a difference.
The main difficulty that I have with the amendments tabled by the noble Lord, Lord Tope, is that they seem to assume the sources of pollution are all local. How do we know unless we have done the research? If we do the research, that immediately gives us the moral and intellectual authority to take action against a particular source of pollution. If we just generalise about these things, we will end up hitting lots of imaginary enemies as well—perhaps—as a real one. It is really important that we get the level of research well up. We should make it local and consistent so that we really understand what is going on when it comes to air pollution.