Wendy Zuckerman

Now, by this point, Rosamund already had a lawyer to help out with Ella's case.

And so her legal team and Stephen got to work.

Here's what they did.

They matched up the pollution levels for the days surrounding when Ella would have these really bad attacks.

And bam.

Oh, gosh.

The team found a pattern.

So Ella's attacks would come in these clusters, and mostly they hit when pollution levels were particularly high.

Much higher than the World Health Organization sets for maximum safe levels of pollution, and higher than the UK government is supposed to allow.

And in the days before Ella died, the pollution levels were bonkers in her neighborhood.

Through his academic research, Stephen had suspected that air pollution might have played a role here.

But now, here was the evidence.

And he was sure.

Pollution had been triggering Ella's asthma attacks.

And it all made a lot of sense.

Because it turned out that Ella's family lived near one of the busiest roads in London.

So all of Ella's life, she'd been breathing in lots of car exhaust and other pollution.

When Rosamund found out about all this, she was shocked.

We're still not sure why Ella's asthma was so deadly.

Like one of her siblings has asthma, but it's not nearly as bad.