It's taken a while for me to get back into the swing of things after my return to London, but at long last here's what happened on the last few, hectic days in Mexico, which included one last day in the field to collect our final samples:

A 05:00 start was a harsh way to take on the most challenging climb of the trip but by then Chiara and Dave were ready. Although as they trooped out to the jeep, heavy limbed, it was hard to discern that they knew it. Your devoted reporter remained on the bench in Amecameca on the basis of a four-only-in-the-jeep rule; jealous of the landscapes the rest of Team Popo would see and the last chance at such physical endeavour.

I wanted to leave town exhausted but I'd just have to leave educated and elated instead. On writing and curation duties, I was to source rock-packing materials, a somewhat vital task, so was spurred on in the role. In preparation, I demolished huevos rancheros and set off with the sun on my face, a less than ideal command of the language and immense purpose.

Forget what you know about eating fried eggs, tortillas, cream and green chilli sauce at different times.

When riding other animals, it's customary to do it contraflow to heavy traffic. 

My insight into the last day of scientific field work on Popo came as the team arrived back at base early in the evening. They looked at the peak of their exhaustion. We dined quietly but when asked how the day went, Dave gave a dazzling smile and explained how in his element he was. 'Where did your energy come from?' I asked. 'I don't know, he replied. It was some kind of euphoria. I just kept on going, following my body rhythms.'

Reaching their highest altitude yet of 4,474m, Chiara too had a strong final day in the field. She described how for her, Hugo had set the pace and by 'making small footsteps in his wake', she could maintain the energy to make it. 'Without Hugo, I would have failed,' she said, with what's become her trademark grin and shrug of the shoulders. 

Hugo: Two steps ahead and a dab hand with a 5kg mallet. He's a field work essential.

Popo: Quietly cultivating a 50-a-day smoking habit.

Beautiful Monarchs converge on an outcrop.

I'll name that layer in one.

Chiara's research will very much depend on the data she generates once she's tested these samples back at the Museum. However, as the week progressed it's clear Dave can already see how his work here will enhance the Museum's collections. The Popo samples from this trip will have context of the type he rarely sees in the collection, with his photographs and field sketches giving an exact visual of the make-up of each outcrop.

This, along with the GPS and field notes places the sample more firmly at it's location and - to fully understand Popo - this helps immensely. 'It was also great to get back into making sketches,' he says. 'To be here to collect from the source is invaluable. I have much more to information to offer those wanting to use these collections now.'

Dave tells me his drawings have been 'enhanced' by years of doodling with his two kids.

Local dining requires rapid response paperware.... In truth, our visit to procure more packaging for the specimens.

Amecameca prepares for a two week festival as we depart (a coincidence?)

I don't know what he's selling but I want one.

Lost Highway: Laden with rocks, Dave and Chiara's taxi takes ten wrong turns too many. Mostly to the right.

If any of you have seen the film, The Canonball Run, you will have some insight into the way Mexican highways and byways work. As Chiara and Dave's taxi heads for Mexico City and the beginning of our journey home, we spot a car boot full of people with their legs sticking out, the vehicle swerving between traffic. My palms begin to sweat at the sight.

The 90 minute journey extends to a joyful five hours as the taxi gets lost and our Sat Nav diverts us to the more 'exhilarating' - i.e. terrifying - parts of town. A lifetime later, we've booked into our hotel and hit the streets of the busiest city I've ever been to and spend the evening re-living the highs and lows of the trip. The sheer volume of people traffic serves only to remind us of the dangers of Popo, a mere 70 kilometres away. It also makes me think of how vital Chiara's research could one day be in predicting their safety.

After a 24hr door-to-door journey from London, Lee and I secure our hire car and take on the streets of Mexico City. The traffic carries us along as it weaves and bobs haphazardly; the pavements are alive with switched on, purposeful looking residents. We’re roused from our jetlag by the hustle and bustle of the roads but crash back down to earth the instant we reach the hotel.

It's bumper to bumper, the vehicles have indicators but I've not yet seen one lit.

There are approximately 24 million people living in Mexico City (that's almost 4 Greater Londons!) and it’s impossible to prepare for the field work ahead without considering the impact this volcano has had on the people that live in its shadow. 15 eruptions have occurred since the Spanish arrived in 1519 A.D. with an unknown quantity before. Then, after fifty years of quiet, in 1994 a series of earthquakes signalled that eruptions had started.

A cloud of ash could be seen over its peak and it fell on the nearby city of Puebla. Civil defense evacuated 19 villages (a population of 31,000 people) east of Popo. By Christmas of that year, the total number of evacuees reached 75,000 and a ban on climbing the volcano for non-scientific visitors has been in place ever since.

A local squeezes through traffic.

We make an early start and drive to Amecameca, the town we’ll use as our base from which to climb Popo. Chic’s ‘Le Freak’ and breakneck-speed Spanish pumps from the radio as we tackle the GPS and the ‘soup’ of traffic. The map and the actual roads don’t always match but wrong turnings show us more of a landscape I already love.

Municipal buses don't come any cooler.

Gentle hustle on the busy streets.

Popo was visible from Mexico City but as we travel out in our car, the built-up scenery subsides to be replaced by quarries and swathes of red earth as the volcano begins to dominate our view. If Lee climbs like he drives he’ll conquer this giant, no problem. I stare in awe at the smoke plumes rising from its summit and think, ‘Will my climbing boots melt up there?’

View from our car on the 115 to Amecameca.

Checked in at our base in Amecameca, we explore the town and gaze up at Popo. You find yourself wanting to see it from wherever you stand.

The bar at Hotel Fontesanta, with neon palms and cutlery timepiece. Oh, and Popo on the horizon. 

Sunset from nearby town San Pedro Nexapa

We’ve arranged to meet National Park official Agustin, to gain access to the park and get closer to Popo. Lunchtime’s late in Amecameca and by 16:00 we’re greeted by a hulking great man with a warm demeanour and an unhurried efficiency. Gabriella and Gisella run the education programme and agree to an escorted drive part way up Popo. Lee and I depart for lunch. You’ve never seen two people eat cactus quesadillas so fast or with so much excitement.

A winding 3,600m drive up to Paso de Cortes, our breathing begins to feel heavy, our heads light. In the thinning atmosphere, I feel oxygen rich and starved all at once. Coordination feels clumsy but our sight is fixed. Lee has climbed further to grab some establishing shots of Popo and has been noticed grinning uncontrollably by one of the rangers. 'Emotion' he says knowingly as he gestures toward him. Chiara and Dave arrived Friday night and the sampling begins on Sunday.

Popocatepetl: Don't hold your breath, you'll need it.

We arrived here by car and this is the closest view non-scientific visitors see. From here, another 300m drive up is Tlamacas and from there, the ascent on foot begins. It’s been so valuable to take in the landscape before the science begins, to spend a little time at altitude and with the people who live with this volcano.

‘It’s exciting to live so close to Popo’ says Nacho, one of the park rangers with an incredible smile. We smile too and whether this is in agreement or the lack of oxygen to our brains, I cannot say. One thing’s for sure, the next 9 days are going to be pretty wild.