The altitude
Mexico City sits at 2,240 metres, which is higher than most European ski resorts and roughly the same as Kathmandu.
Most visitors feel something on the first day or two: breathlessness on stairs, a headache, poor sleep, tiring faster than expected. Alcohol hits noticeably harder, which catches people out on the first evening.
What helps: an easy first day, drinking a great deal of water, going lightly on alcohol for the first 48 hours, and not planning to climb a pyramid on day one.
Serious altitude sickness is uncommon at this height but not unknown. Persistent severe headache, vomiting or breathlessness at rest needs medical attention.
Anyone with a significant heart or lung condition should take advice before travelling.
The earthquakes
Mexico City is not on a fault. Its problem is that it is built on the drained bed of Lake Texcoco, on soft saturated clay that amplifies seismic waves arriving from the Pacific subduction zone hundreds of kilometres away — and can resonate for minutes.
19 September 1985 — magnitude 8.0. Several thousand died; the official figure of around 5,000 is widely regarded as low, with estimates running to 10,000 or more.
19 September 2017 — magnitude 7.1, thirty-two years to the day, and a few hours after the city’s annual commemorative earthquake drill. Around 370 died.
The coincidence of dates is real.
What to do
Mexico City has a seismic alert system, the SASMEX. Sensors near the coast detect a quake and broadcast a warning that reaches the city up to 60 seconds before the shaking — the P-waves travel faster than the destructive S-waves, and the distance buys that minute.
It sounds like a loud rising alarm from street speakers, and phones with the app receive it too. Download SkyAlert or the official 911CDMX app.
When it sounds:
- If you can leave the building quickly and safely, do. Follow the green signs to a punto de reunión.
- If you cannot, get away from windows and stand in a zona de seguridad — usually marked, often a load-bearing column or a doorway on a lower floor.
- Do not use lifts.
- After shaking stops, expect the building to be evacuated and checked.
There is a national drill each 19 September and smaller ones through the year. If you are here for one, take part; the whole city does.
Buildings constructed since 1985 are built to a much stronger code, and modern hotels are considerably safer than the older stock.
The safety question
The one everyone asks about, and the answer is more specific than the reputation.
Violent crime against tourists in the central districts is uncommon. The cartel violence that dominates coverage of Mexico is largely concentrated in particular states and border regions and is not the story in the Roma, Condesa, Centro, Coyoacán or Polanco.
What does happen is opportunistic: pickpocketing on crowded metro lines and at markets like La Lagunilla, phone snatching, and robbery in unlicensed taxis.
The rules that actually reduce risk:
- Never hail a street taxi. Use Uber, DiDi or a sitio rank.
- Carry what you need and no more. No visible phone in crowds, nothing in a back pocket.
- Use ATMs inside banks or malls during the day.
- Avoid deserted streets late at night; the central districts are busy and fine.
- Check current advice for outlying boroughs; Tepito and parts of Iztapalapa are not tourist areas.
Mexican government travel advisories rate Mexico City lower risk than a number of US cities. It is worth reading your own government’s advice and reading what it actually says about the capital rather than the country.
Water
Do not drink the tap water. Bottled and filtered water is universal, and restaurants use purified water for ice and washing salad as a matter of course.
Agua purificada is what to ask for.
Most visitors who get ill have a mild upset for a day. Take rehydration salts.
Air
Mexico City sits in a basin ringed by mountains, which traps pollution. Air quality has improved a great deal since the 1990s but bad days still occur, particularly in the dry season from February to May.
The city declares a contingencia ambiental on the worst days, restricting traffic. Anyone with asthma should carry their inhaler and check the index.
What locals actually do
Worth noticing, because it is instructive.
Everyone has the seismic alert app. Buildings run drills. Green zona de seguridad markings are on floors and walls in offices, hotels and metro stations, and people know where theirs is.
Nobody hails a street taxi. Everyone uses Uber or a sitio.
Nobody drinks the tap water, and every home has a garrafón — a twenty-litre bottle on a dispenser.
Copying all four is the whole of the practical advice.