The full equation

Two components, no double counting

The heat tax has two distinct parts that affect different populations. The first — lost income — hits workers exposed to heat, those without air conditioning. The second — the AC premium — hits those who have it, in the form of electricity bills. These aren't the same people. There's no double counting.

That's what makes the total so striking: whether you have AC or you don't, you pay. Exposed workers pay in hours of productivity. Air-conditioned businesses pay in kilowatt-hours. Heat taxes everyone — it just collects in different currencies.

Heat Tax = Lost Income + AC Premium

Lost Income = hours_lost × hourly_wage × exposed_workers
            = 730 h × (1.4 × SMIG / 2,600 h) × 120,000
            = 1,769 M MRU

AC Premium  = equipped_spaces × annual_consumption × SOMELEC_rate
            = 31,432 × kWh_month × 12 × 5.903 MRU/kWh
            = 869 M MRU

Total       = 1,769 + 869
            = 2,638 M MRU
            ≈ $73M USD / year

What the city loses

$73 million per year. That's what heat subtracts from Nouakchott, by our central estimates. The low scenario gives around $50 million; the high exceeds $100 million. Even the lower bound represents a considerable cost for a city of this size.

What this means

$73 million is a number you can compare. It's more than the annual budget of several Mauritanian ministries. It's the equivalent of thousands of salaries. It's a structural brake the city drags every year, without anyone having ever quantified it this way.

And it's a conservative number. We don't count peri-urban agricultural losses. We don't count health impacts — heat-related hospitalisations, chronic fatigue, effects on children and the elderly. We don't count the productivity loss of formal workers in poorly air-conditioned offices. We count only what's measurable with available data.

The central finding — Nouakchott operates at 80% of its potential — is an observation, not an accusation. The climate is what it is. But a cost that's been measured is a cost you can start to reduce.