Air quality and pollution

What AQI measures

The Air Quality Index (AQI) combines several pollutants — PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide, carbon monoxide — into a single 0–500 scale. In Chinese cities, PM2.5 (particulate matter under 2.5 microns in diameter) is the dominant pollutant and the primary health concern. PM2.5 particles penetrate deep into the lungs and cardiovascular system; long-term exposure is the public health issue, while short-term high-exposure causes respiratory irritation in most people and is more serious for those with asthma, COPD, heart disease, or young children.

The AQI scale used in China (Chinese AQI, CAQI) uses different breakpoints from the US EPA AQI. Chinese air quality data published by Chinese authorities generally tracks with international monitoring, though some minor discrepancies exist. The apps below pull data from US Embassy monitoring stations in addition to Chinese government data, which provides independent verification.

AQI bands and what they mean for your day:

Apps to install before departure

IQAir / AirVisual: The most widely used app among foreign residents in China. Shows real-time AQI from multiple monitoring sources including US Embassy stations. Hourly and forecast data. Widget available for home screen. Download before arrival (it's blocked on some Chinese networks without a VPN).

AQICN (aqicn.org): Web-based; also has an app. Shows all monitoring stations on a map; useful for seeing variations across a city.

Apple Weather / iOS: Built-in weather apps for iOS include AQI data for Chinese cities — no additional app needed if you're on iPhone.

Android weather widgets: Many Android weather apps include AQI; confirm your widget shows AQI before departure.

Masks: what works and what doesn't

KN95: The Chinese standard equivalent of N95. Rated to filter 95% of PM2.5 particles when properly fitted. Available everywhere in China — pharmacies, convenience stores, supermarkets — for ¥3–10 per mask [VERIFY: current retail price — May 2026]. The most practical option for travellers.

N95 (US standard) / FFP2 (EU standard): Both provide equivalent or better protection than KN95. Bring your own from home if you prefer a specific brand.

KF94 (Korean standard): Also rated effective for PM2.5. Popular among expats for its boat-shaped design that provides a better fit for non-Asian face shapes.

Surgical masks / cloth masks: Do NOT filter PM2.5. They stop droplets but cannot capture particles in the 2.5-micron range. Wearing a surgical mask at AQI 250 provides essentially no protection against the relevant pollutant.

Fit matters more than brand: a KN95 worn loosely with gaps at the sides provides minimal protection. Pinch the nose wire, press the mask against your cheeks, and check for a seal before relying on it.

Worst periods and regions

**Beijing and Hebei (including Tianjin)**: The North China Plain historically had the worst air quality in China. The worst periods are November–February (heating season, when coal and gas consumption for indoor heat peaks) and March–April (dust storms from the Gobi Desert). Beijing has improved substantially since 2013 — average annual PM2.5 has halved — but severe episodes still occur several times per winter.

**Shanghai and the Yangtze Delta**: October–January brings winter inversions — when cold, stable air traps pollution near the surface. The basin geography of the Yangtze Delta makes ventilation poor. The region is cleaner than Beijing historically, but winter inversions can push AQI to 150–200.

**Chengdu and the Sichuan Basin**: Chengdu sits in a topographic bowl with limited natural ventilation. Low-grade haze is persistent, with winter (November–February) being the worst. Unlike the North China Plain, Chengdu's haze is dominated by industrial and transport emissions rather than coal heating. Even in summer, AQI rarely reaches 'good' in Chengdu.

**Pearl River Delta (Guangzhou, Shenzhen), Hong Kong**: Generally cleaner than northern China; better ventilation from the South China Sea. January–February can see occasional spikes. Hong Kong publishes its own AQHI (Air Quality Health Index), which is separate from the Chinese AQI system.

**Xinjiang, Gansu**: Desert dust storms in spring (March–May) can push PM10 to extreme levels in Turpan and Dunhuang; these are natural events, not industrial pollution. Outside dust-storm events, air is typically clean.

**Yunnan, Hainan, Tibet**: The cleanest air in China. Yunnan's altitude and southwest monsoon provide ventilation; Hainan's tropical marine climate is clean; Tibet's altitude and limited industrial activity produce clean, thin air. Even Kunming — with significant traffic — typically has AQI in the 'good' range.

What has improved since 2013

The improvement in Chinese air quality since 2013 has been one of the most significant environmental achievements of the past decade:

• Beijing's annual mean PM2.5 concentration fell from approximately 90 μg/m³ in 2013 to roughly 35–40 μg/m³ by 2023–24. Still above the WHO guideline (5 μg/m³), but a substantial reduction.
• Hebei province's notoriously polluted industrial cities (Shijiazhuang, Baoding) have shown similar trends.
• The National Action Plan on Air Pollution (2013–2017) and its successors mandated coal-to-gas conversions for residential heating, factory relocations, and tighter vehicle emission standards.

The improvements are real and measurable. For travellers, the practical consequence is that severe 'airpocalypse' events (AQI 500+) are now rare in Beijing, whereas they occurred several times annually a decade ago. Moderate pollution (AQI 100–150) on winter days is still common.

Practical travel strategy

• Check AQI the night before planned outdoor activities (Great Wall, Forbidden City exterior, Bund walks, long hikes). Reschedule indoor activities to bad-air days.
• Pack KN95 masks from home — they're lighter and better-fitting when brought in your own size than when purchased in a hurry.
• Hotel rooms with air purifiers are increasingly standard at international hotels in Beijing and Shanghai. If staying somewhere without one, a portable travel purifier (Coway, Xiaomi 4 Lite) is an option for a longer stay.
• The Beijing hutong neighbourhood streets tend to have lower AQI than main arterial roads — less traffic, more tree coverage.