Background Urban air pollution resulting from economic growth as well as urbanization impacts the health of inhabitants. This study aims to examine the spatial distribution of particulate matter (PM10) and the risk of exposure for the population in the Klang Valley, an urban conglomeration centred in Kuala Lumpur, Malaysia. Methods The inverse distance weighted (IDW) interpolation technique in the ArcGIS platform was used to map the air quality from five air monitoring stations. Spatial statistics of the Global Moran’s I Spatial Autocorrelation and Optimized Hot Spot Analysis were used to estimate the spatial clustering of PM10. The population-weighted exposure level (PWEL) technique was used to calculate the population density susceptible to PM10 and the AirQ+ model was applied to estimate the proportion of the adult population at risk of chronic bronchitis due to long-term exposure to PM10 concentrations in the Klang Valley. Results The highest annual mean PM10 concentrations at the Klang station ranged between 80 and 100 μg/m3 from 2000 to 2009 and exceeded the New Malaysia Ambient Air Quality Standard (NMAAQS) and the World Health Organization Air Quality Guidelines (WHOAQG) levels of 40 and 20 μg/m3, respectively. The Moran's I results indicated that the statistically significant clusters of high PM10 in Klang present a health risk to the local community. The PWEL results showed that levels of PM10 in Petaling Jaya exceeded the WHOAQG limits, potentially posing a health risk to the high-density population. The AirQ+ model found Klang to be a significantly high-risk area for chronic bronchitis among the adult population with 804,240 people (with a relative risk of 1.85) in 2009. Conclusion These high-risk values are due to rapid urbanization and high motor vehicle usage in the Klang Valley and therefore the impact of PM10 on the population needs to be reduced. This situation should be taken seriously by the Department of Environment and Kuala Lumpur City Hall in addressing air pollution issues through stricter rules on emissions and implementing low-carbon policies to improve the well-being of residents.

Air pollution in Malaysia is largely attributed to motor vehicles and land transportation, industrial activities and open burning. It has a hazardous effect on the public’s health and the environment. This study focuses on the spatial analysis of carbon monoxide (CO) and ozone (O3) concentrations trend in Klang Valley stations, specifically in Klang, Petaling Jaya, Kajang, Shah Alam and Cheras from 2000 to 2009. The study used the Inverse Distance Weighted (IDW) interpolation technique under the Geographic Information System (GIS). This study found that the distribution pattern of CO spatial concentrations in the Klang Valley is the highest concentration and reached 2.5 ppm, especially in Klang and Petaling Jaya stations in 2002 and 2003. However, the annual concentration of O3 recorded in Klang, Petaling Jaya, Kajang, Shah Alam, and Cheras stations from 2004 to 2009 is between 0.01 to 0.025 ppm. While air quality legislations have been introduced in Malaysia, policies and regulations being established by the government, their enforcement is still weak. Subsequently, air pollution is still a significant issue in Malaysia. Strong cooperation between the government, stakeholders and the local community is important to promote environmental sustainability and improve the community’s well-being. Keywords: Air pollution; Geographic Information System (GIS); Air Quality Policy; Malaysia