Simply reducing methane and black carbon, which comes from diesel engines, cook stoves and wood burning, could cut the rate of climate change in half for the next several decades, reduce by as many as 2.4 million the number of people who die from air pollution every year and avoid annual crop losses of more than 100 million tonnes.

In sub-Saharan Africa, using low-sulphur fuels and cleaning up vehicles could result in health benefits that add up to $43 billion over a ten-year period.

For our own health and the health of our economies, the cost of failing to act is as damaging as the smog that shrouds our cities. The need to act is as clear as the air we want to breathe.

Luckily, we already know what we need to do to catch the killer in our midst. We need to shift to clean modes of power generation, improve urban transport and switch to cleaner, low emission vehicles and fuels. Green technologies can reduce the harm done by industrial smokestack emissions and limit the pollution from traditional cook stoves, and urban and agricultural waste. Improving the way we build our cities will also have a major impact in the fight against outdoor air pollution.

We're already seeing encouraging signs of change. In 2014, China announced plans to remove from the roads as many as six million vehicles that do not meet emission standards. The gradual phasing out of leaded petrol, which is now used in only three countries thanks to an initiative led by the United Nations Environment Programme, helps to avoid roughly 1.3 million premature deaths every year.

But more needs to be done. That is why in Colombia last month ministers and high-level officials from 33 countries in Latin America and the Caribbean adopted the Declaration of Cartagena, which calls for urgent action and increased financing to cut the emissions of short-lived climate pollutants (SLCPs) – methane, black carbon, hydrofluorocarbons and tropospheric ozone.

By tackling air pollution we also stand a far greater chance of achieving some of the Sustainable Development Goals set out in the 2030 Agenda –food security, healthy lives for all, safe cities and access to clean energy.

This is why countries like mine and others from Latin America and the Caribbeanwill be pushing for ambitious resolutions and tough decisions at the upcoming United Nations Environment Assembly (UNEA), which will be held in Nairobi next month (MAY).

It is vital that the world sees UNEA – the world's most powerful decision-making body on the environment – as an opportunity to tackle the world's most severe environmental health emergency.

The silent killer that stalks our streets and cloaks our cities in clouds of filth must be stopped. If we want a future where we don't have to put on surgical masks every time we step outside, where our children can go to school every day without fearing for their health, then we must place the menace of air pollution at the top of the world's "most wanted" list. If we don't, then we will continue to poison the health of our people and the power of our economies.

The author is the Minister of Environment for Peru.