In December, 1952, London was gripped by a “great smog” that wreaked havoc on the city for days and resulted in several thousand deaths. The severity of the event provided a wake-up call to legislators and prompted a series of regulatory changes to address the problem of air pollution in UK cities, including the landmark Clean Air Act of 1956. 60 years on, however, the health effects of air pollution are still unacceptably high. In 2013 alone, exposure to one type of air pollution—particulate matter less than 2·5 μm in diameter (PM2.5)—was estimated to be responsible for almost 40 000 premature deaths in the UK. Overall, data presented in the Nov 23, 2016, European Environmental Agency (EEA) report on air quality in Europe indicates that air pollution is responsible for an estimated 467 000 premature deaths each year across 41 European countries.
But back in 2003, according to government figures, "only" 29,000 deaths were attributed to that cause by the government. [Number of the Month, April 2011]
So despite more stringent emission controls, more deaths are attributed. 50% more! Notably; deaths without graves.
The government response, apparently supported by Lancet, is even stricter emission controls.
Proverbs 26:11 comes to mind. Apt because it's failures/foolishness of biblical proportions.
P.S. Further mentions in e.g. NotM June 2001: It's important because we can (now) measure it. Recent mention in NotM July 2013 "By the way, whatever happened to diesel particulate filters and catalytic converters?"